.277 Fury 16.5” shorty bolt report

[ElvisUSMC]

Disclaimer: I don’t post much so apparently I’ve saved up for this one. I put this together during some spare time when home on leave and I won’t be able to refine this for another year. This isn’t a full detailed review of the .277 Fury cartridge, I didn’t have time to do a full Chrono and accuracy, everything I slapped together was AdHoc. SO I admit to not doing a complete job and the errors in my method, I will just post the results for your own determination.

Several months ago, I decided with all of the Washington and Oregon gun control idiocracy against gas-guns I wanted a short, compact bolt gun that wasn’t an NFA stamp’er, a general multipurpose tool. I had a ARC Nucleus Gen 1 that I’ve had since Ted introduced them and never could get it to feel right in a rifle between 25 CM, 6.8 Western, and .284 Win barrels of different lengths. After researching the .277 Fury / 6.8x51mm cartridge (not the SPEAR rifle) from Sig I figured I’d give it a shot for the reported performance in A 16” barrel. I have listened to all of the podcasts and scrubbed the forums for info on shooting the .277 Fury, but all of it was completely speculative information, not from functional use. Even Ron Spomer had a podcast talking about how a .277 Fury might “BLOW UP A RIFLE!!” My opinion, disappointing ignorance in rifle construction, and 80k psi max (hybrid case) cartridge is not going to blow up a bolt rifle rated to 120K+PSI, otherwise SAMMI never would of approved it. If you slapped a .277 Fury barrel on a AR-10 (not the SIG SPEAR), you might have cause for concern, but not a good bolt action, again, in my opinion.
For ~16” barrel cartridge selection, I have a 16” .308 gasser and that has it’s purpose. I looked at the 8.6 CM/Blackout and have serious skepticism about the marketing vs. performance and .375 Raptor was cool, but too boutique. After looking across the expanse of the internet, or just asking Google, I found ammo for an acceptable price and also found someone who offers Savage pre-fits chambered in .277 Fury. Here is the resulting rifle.

Action: ARC Nucleus Gen 1 (30 MOA rail, 19lb striker spring)
Tigger: Huber 2-stage
Barrel: McGowen 16.5”, .277 Fury, 1-7”R twist, Savage Pre-Fit, ARC BARLOC
Stock: Manners TA (Altus Highland Camo), Devcon Pillar bedded
Bottom Metal: Badger M5 Enhanced
Scope: Nightforce NX8 2.5-20x50
Rings: ARC
Muzzle: Silencer Co Single Baffle Break
Can: Silencer Co Harvester 300
Total weight: 10lbs (a bit heavier than I wanted)

AMMO: There are current 3x versions of the .277 Fury ammo on the market from Sig. The 132gr Ball (standard case), the 130gr VENARI Soft Point (standard case), and the 150gr Elite Bonded Poly tip (Hybrid case). These all can be found at online vendors and I was able to secure plenty of rounds of the 132gr Ball and 150gr Hybrid for prices that didn’t make me sick to my stomach, or get scammed by some online F’head.

This is where it gets interesting…

As you can see the box velocity for 16in and 24in barrel lengths for both the standard load and higher pressure “hybrid’ load. Box velocity for the 150gr Hybrid case is 2830fps for a 16” barrel and 3120fps for a 24” barrel! That’s outpacing the .270 Win.

The Gen 1 Nucleus is finally at home and feels right in this compact rifle with it’s short stout bolt throw. The rifle is easy pointing and easy to carry, I am very happy with how it all came together.

For the ammo: The 132gr Ball is soft shooting and really pleasing to shoot in the shorty rifle, recoil on par with 6.5 CM or 6.5x47L. The 150gr Hybrid, is definitely spicer in recoil, but not significantly so. In this rifle set up, this doesn’t shoot like my Dad’s old wood stock 30-06’s where after a few rounds you are picking up a subconscious flinch, it is easy like Sunday morning. The ammo performance to barrel length make for a really pleasing Bolt gun.

This is where my testing/scientific method goes to shit as I was out of time and due to the surrounding environment, did not want to shoot without a can on; I was shooting on our property, but harvest was going on the properties adjacent, no need to spook the Pickers, the bullet reports were enough to unsettle them.

When I finally got the Lab Radar to work with the suppressor on the rifle, I had gone through the 132gr Ball ammo I had with me at the table, so no results to report there, which I regret terribly. But….

Yeah, that reads right, 3015fps and 3019fps for the 2 of 5 rounds I could get to record on the Lab Radar (yes, I know this isn’t a complete shot spread SD/ES average so take the SD of 3.2 with a health dose of skepticism). This was WITH the Harvester 300 can ON, which is a long suppressor. However I do not believe that increasing box listed velocity from 2830fps to 3017fps is because of the can, ~50fps sure, but not 187fps.

Here is a look at the primers to show signs of pressure. You can definitely see the pressure signs on the Hybrid case primer.

As I stated in the beginning, not a complete report. I would love to group the gun with this off-the-shelf ammo and then take it out to distance. I will say I love the feel of the rifle with the short barrel and it shoots beautifully. I think the .277 Fury has a lot of potential if people can get over the ”new tech” of it, a 150gr bullet moving at 3015fps out of a 16” barrel is significant. We’ll see if I still have rifling in a 1000 rounds through the barrel, but this isn’t a match gun. For perspective, my 6.8 Western with a 24” barrel shoots 162gr Copper Impacts at 2960fps! That is a short mag cartridge with a lot more powder for like performance. Arguably, the 6.8 Western will probably do better with the heavier +170gr .277 bullets than the .277 Fury Hybrid just due to space for slower burning powders. For now the .277 Fury in this shorty rifle worked out a lot better than I expected.

Take what you want from this report, it’s just raw data.

For my Marine brethren, Crayons and Bourbon is in the corner.
For the Trolls, White Claws and lotion is in the other, do what you want, just don’t look us in the eye.

S/F
Elvis

 

[wigwamitus]

thx a bunch for the report - infinitely more real world data than i've seen so far !
I got me some 150 hybrid ammo, but no gun yet. Been waitin for the cross ...

 

[45-90]

I run the 277 Fury hybrid cases in 308 and 6.5 Creedmoor. As no one had a reamer in stock and fast twist .277 barrel blanks were not in. Yes both actions I used take the 80,000 psi loads. Your pressure signs are normal in the 80,000 psi loads, no marks on the SS heads but the primer cup will extrude into the firing pin hole. I ran the 140 Nosler RDF at 3156 fps in a 24" factory 6.5 Creedmoor barrel with factory action and hybrid cases. The 150 SMK and 153 Atip reached 3050 fps, but I like them just under 3000 fps for accuracy. The 308 had 200 gr SMK 715 BC bullets over 2900 fps in a long barrel, with hybrid cases, 168 to 3256 fps, as an example of hybrid cases, but I found an interesting feature in the 9 twist 22" bolt gun was accuracy with hybrid cases was better than Lapua case with LR or SR primers installed with 230 gr SMK, and other match bullets, but it requires a bit more powder to reach the same velocity in the hybrid cased, as they have more capacity than Lapua, for normal high pressure loads, like 65,000 psi, area instead of 80,000 psi.
I believe there is a difference in the energy transfer to the powder charge, the SS hybrid casehead is not hot like the brass head, after it has been fired, transferring more energy into the powder charge while the brass heads absorb energy through greater heat transfer during the powder burn..I have fired the hybrid cases in 308 and 358Win auto loaders with normal loads, they work fine, and I've reloaded the first 100 4 times primer pockets still nice and tight. Trim after firing, the 1st time they grow when the 80,000 psi is put to the case..
Stop if the action opening begins to get stiff, the case is fine but you are stressing the action, and over 80,000 psi...and the primer teat will grow long as the primer reaches 90,000 psi. But the SS will not have a mark on it and the primer pocket will be fine when gauged. So more caution is needed here... I never blew a primer or had a casehead mark in all the testing, over 400 rds....but I've checked the action with chamber gauges for lug set back as I know the 80,000 psi has been crossed a few times. There is a marked improvement with every cartridge I tried hybrid cases in, some much better than others ...but you can only take what it gives ya with the powders available.

 

[ElvisUSMC]

I run the 277 Fury hybrid cases in 308 and 6.5 Creedmoor. As no one had a reamer in stock and fast twist .277 barrel blanks were not in. Yes both actions I used take the 80,000 psi loads. Your pressure signs are normal in the 80,000 psi loads, no marks on the SS heads but the primer cup will extrude into the firing pin hole. I ran the 140 Nosler RDF at 3156 fps in a 24" factory 6.5 Creedmoor barrel with factory action and hybrid cases. The 150 SMK and 153 Atip reached 3050 fps, but I like them just under 3000 fps for accuracy. The 308 had 200 gr SMK 715 BC bullets over 2900 fps in a long barrel, with hybrid cases, 168 to 3256 fps, as an example of hybrid cases, but I found an interesting feature in the 9 twist 22" bolt gun was accuracy with hybrid cases was better than Lapua case with LR or SR primers installed with 230 gr SMK, and other match bullets, but it requires a bit more powder to reach the same velocity in the hybrid cased, as they have more capacity than Lapua, for normal high pressure loads, like 65,000 psi, area instead of 80,000 psi.
I believe there is a difference in the energy transfer to the powder charge, the SS hybrid casehead is not hot like the brass head, after it has been fired, transferring more energy into the powder charge while the brass heads absorb energy through greater heat transfer during the powder burn..I have fired the hybrid cases in 308 and 358Win auto loaders with normal loads, they work fine, and I've reloaded the first 100 4 times primer pockets still nice and tight. Trim after firing, the 1st time they grow when the 80,000 psi is put to the case..
Stop if the action opening begins to get stiff, the case is fine but you are stressing the action, and over 80,000 psi...and the primer teat will grow long as the primer reaches 90,000 psi. But the SS will not have a mark on it and the primer pocket will be fine when gauged. So more caution is needed here... I never blew a primer or had a casehead mark in all the testing, over 400 rds....but I've checked the action with chamber gauges for lug set back as I know the 80,000 psi has been crossed a few times. There is a marked improvement with every cartridge I tried hybrid cases in, some much better than others ...but you can only take what it gives ya with the powders available.

45-90,
Thank you for the detailed info on loading the hybrid cases. That’s good experience based data. I’ll eventually get into loading for it, when I move back from overseas and can set up my reloading room again.

 

[ElvisUSMC]

thx a bunch for the report - infinitely more real world data than i've seen so far !
I got me some 150 hybrid ammo, but no gun yet. Been waitin for the cross ...

I was looking for the Cross in .277 but the only ones in online store fronts are scams. I’ve talked to Sig, the Cross in .277 Fury won’t be out until this winter, at earliest, if it comes out within the next year at all. I just decided to go with a barrel and build from parts I already had and am pretty happy.

 

[Xfrog]

I was looming at getting a barrel spun up and called around. One seller says they got stupid high velocities from a 16.5" barrel but accuracy was shit and sd really high. They cut it 8 twist. Maybe 7 or 7.5 is needed? Please post up when you get some time behind that sweet rifle!

 

[ElvisUSMC]

I was looming at getting a barrel spun up and called around. One seller says they got stupid high velocities from a 16.5" barrel but accuracy was shit and sd really high. They cut it 8 twist. Maybe 7 or 7.5 is needed? Please post up when you get some time behind that sweet rifle!

Xfrog, mine is a 1-7” which bumped with the SIG SPEAR twist rate. Still no accuracy testing. I’ll post the next time I’m back from Japan and group test it.

 

[Idahank]

I run the 277 Fury hybrid cases in 308 and 6.5 Creedmoor. As no one had a reamer in stock and fast twist .277 barrel blanks were not in. Yes both actions I used take the 80,000 psi loads. Your pressure signs are normal in the 80,000 psi loads, no marks on the SS heads but the primer cup will extrude into the firing pin hole. I ran the 140 Nosler RDF at 3156 fps in a 24" factory 6.5 Creedmoor barrel with factory action and hybrid cases. The 150 SMK and 153 Atip reached 3050 fps, but I like them just under 3000 fps for accuracy. The 308 had 200 gr SMK 715 BC bullets over 2900 fps in a long barrel, with hybrid cases, 168 to 3256 fps, as an example of hybrid cases, but I found an interesting feature in the 9 twist 22" bolt gun was accuracy with hybrid cases was better than Lapua case with LR or SR primers installed with 230 gr SMK, and other match bullets, but it requires a bit more powder to reach the same velocity in the hybrid cased, as they have more capacity than Lapua, for normal high pressure loads, like 65,000 psi, area instead of 80,000 psi.
I believe there is a difference in the energy transfer to the powder charge, the SS hybrid casehead is not hot like the brass head, after it has been fired, transferring more energy into the powder charge while the brass heads absorb energy through greater heat transfer during the powder burn..I have fired the hybrid cases in 308 and 358Win auto loaders with normal loads, they work fine, and I've reloaded the first 100 4 times primer pockets still nice and tight. Trim after firing, the 1st time they grow when the 80,000 psi is put to the case..
Stop if the action opening begins to get stiff, the case is fine but you are stressing the action, and over 80,000 psi...and the primer teat will grow long as the primer reaches 90,000 psi. But the SS will not have a mark on it and the primer pocket will be fine when gauged. So more caution is needed here... I never blew a primer or had a casehead mark in all the testing, over 400 rds....but I've checked the action with chamber gauges for lug set back as I know the 80,000 psi has been crossed a few times. There is a marked improvement with every cartridge I tried hybrid cases in, some much better than others ...but you can only take what it gives ya with the powders available.

45-90, what length is the “long” barrel of your 308?

 

[45-90]

45-90, what length is the “long” barrel of your 308?

The 308 in this test was a Bartlein 5 R 30" 8 twist 308 Win LA bolt gun for 200 to 250 gr bullets. Originally ordered for a 300 RUM project, but chambered it in 308 first...and I liked it, for accuracy & performance increase with newer components. I have many 308s from 16,18,20,22,24,26, 27,30, inch barrels ARs and bolts, twists 12, 11.25, 10 , 9, & 8. And have explored the cartridge extensively. It's not the old inefficient 168 gr load these days with the new components and fast twists employed...but shooting .7 and .8 BC bullets at good velocities. The hybrid cases provide another improvement in small arms...standard cases get magnum performance.

 

[z987k]

I've reloaded for it, just with some copper monos, but I've got other bullets loaded to try. Using GRT to try to model pressure and not go past 80k while working up.
You really can't read pressure on the case with these.

With a 140gr SBD-2 loaded at 2.950, in a 18" barrel, suppressed, I got to 2970fps with where grt predicted 80k to be. I saw better accuracy at 2955fps.

 

[Woodenyeti]

The 308 in this test was a Bartlein 5 R 30" 8 twist 308 Win LA bolt gun for 200 to 250 gr bullets. Originally ordered for a 300 RUM project, but chambered it in 308 first...and I liked it, for accuracy & performance increase with newer components. I have many 308s from 16,18,20,22,24,26, 27,30, inch barrels ARs and bolts, twists 12, 11.25, 10 , 9, & 8. And have explored the cartridge extensively. It's not the old inefficient 168 gr load these days with the new components and fast twists employed...but shooting .7 and .8 BC bullets at good velocities. The hybrid cases provide another improvement in small arms...standard cases get magnum performance.

Curious what powders you're finding applicable for .308? I'm going back and forth on ordering a box or 2 of the hybrid cases to tinker with, and .308 would be the first to run it in, with 175-178 class projectiles to start. Currently running a shade over 2600 out of a 20" howa with 178 eldm, varget, and LC LR brass. Even if I stay at this pressure level the hybrid cases should theoretically last as long or longer than lapua small primer and are a good bit cheaper currently. As for venturing above, I'm not sure I can cram much more varget in them without belling the seating cup on my forster mic seater. Cfe223 and LVR would be my next 2 guesses, but LVR seems to get awful spiky at top end in 6arc.

I run 147 eldm at 2900 in 6.5cm with RL26 for a hunting load. Same benefits should apply there, but I dont have a neck turning setup and assume you'd probably need one to deal with the extra from necking down there...so 308 would be the first I tinkered with. Should be able to just run it in a mandrel sizing die and trim there though I'd think.

Completely understand if you don't want to put the info out there, never know who will just grab it and run without knowing what they are doing. PM would work, and if not, completely understand. I still may get some, measure volume, and tweak GRT to match velocities.

 

[z987k]

Curious what powders you're finding applicable for .308? I'm going back and forth on ordering a box or 2 of the hybrid cases to tinker with, and .308 would be the first to run it in, with 175-178 class projectiles to start. Currently running a shade over 2600 out of a 20" howa with 178 eldm, varget, and LC LR brass. Even if I stay at this pressure level the hybrid cases should theoretically last as long or longer than lapua small primer and are a good bit cheaper currently. As for venturing above, I'm not sure I can cram much more varget in them without belling the seating cup on my forster mic seater. Cfe223 and LVR would be my next 2 guesses, but LVR seems to get awful spiky at top end in 6arc.

I run 147 eldm at 2900 in 6.5cm with RL26 for a hunting load. Same benefits should apply there, but I dont have a neck turning setup and assume you'd probably need one to deal with the extra from necking down there...so 308 would be the first I tinkered with. Should be able to just run it in a mandrel sizing die and trim there though I'd think.

Completely understand if you don't want to put the info out there, never know who will just grab it and run without knowing what they are doing. PM would work, and if not, completely understand. I still may get some, measure volume, and tweak GRT to match velocities.

Use the parametric powder search in GRT. Top powders for 80kpsi in a 308 sized case are LT-30, H335, LvrE. Things you wouldn't associate with a magnum.

 

[Woodenyeti]

Use the parametric powder search in GRT. Top powders for 80kpsi in a 308 sized case are LT-30, H335, LvrE. Things you wouldn't associate with a magnum.

That was roughly my plan of action, thanks!

I'll probably pick up 100 to tinker with next time I catch them cheap. How has consistency been so far with the brass? Good ES/SD or more like mil brass? Currently running 1x LC LR around 9-14 s.d. (good enough for me for now) with a chargemaster and varget, annealing, and redding SB die with carbide expander button. I have a mighty armory die coming, so should be able to just run the hybrid case in that die then trim if needed since it has a mandrel to expand instead of button.

 

[Im2bent]

277 Fury / 6.8x51mm SIG Primed "Hybrid" Case - 100ct - American Reloading

ALL CASES CONTAIN STUCK POWDER Pulled, Primed Brass - Casings may contain minor dents/scratches *All casing should be resized prior to loading

americanreloading.com

 

[Woodenyeti]

277 Fury / 6.8x51mm SIG Primed "Hybrid" Case - 100ct - American Reloading

ALL CASES CONTAIN STUCK POWDER Pulled, Primed Brass - Casings may contain minor dents/scratches *All casing should be resized prior to loading

americanreloading.com

Yup, I've been watching them off and on since they started carrying them. They went up $40 per from when I added to my cart this am, I'll catch them on sale again before long though. I ordered lots from AR over the years on their old site.

 

[45-90]

Curious what powders you're finding applicable for .308? I'm going back and forth on ordering a box or 2 of the hybrid cases to tinker with, and .308 would be the first to run it in, with 175-178 class projectiles to start. Currently running a shade over 2600 out of a 20" howa with 178 eldm, varget, and LC LR brass. Even if I stay at this pressure level the hybrid cases should theoretically last as long or longer than lapua small primer and are a good bit cheaper currently. As for venturing above, I'm not sure I can cram much more varget in them without belling the seating cup on my forster mic seater. Cfe223 and LVR would be my next 2 guesses, but LVR seems to get awful spiky at top end in 6arc.

I run 147 eldm at 2900 in 6.5cm with RL26 for a hunting load. Same benefits should apply there, but I dont have a neck turning setup and assume you'd probably need one to deal with the extra from necking down there...so 308 would be the first I tinkered with. Should be able to just run it in a mandrel sizing die and trim there though I'd think.

Completely understand if you don't want to put the info out there, never know who will just grab it and run without knowing what they are doing. PM would work, and if not, completely understand. I still may get some, measure volume, and tweak GRT to match velocities.

Those who venture into the 80,000 psi hybrid case must not be beginners. First it's not recommend for anyone...the cases were not reloadable, no dies, available...forget firearm warranty, etc.
But sometimes we have to challenge the narrative.
I found the cases reloadable with the various factory dies, 4 times so far...on other projects now. But here is the basic information. The cases are hybrid, powder energy in the form of heat to the case is much less...where does the energy go ...into velocity most likely.
You are not fucking around here this is very serious shit, at 80,000 psi everything matters.
You must know the exact water volume of your case period... I own my reamers and the chamber barrels...I do not have someone "spun up" anything, immature slang, that describes nothing.
You must chronograph. And pressure signs are not prevalent, like on brass cases. These cases appear they will take 100,000 psi, but your rifle may become a grenade in your face, or pieces of SS case head.
Here are some 308 cases marked with powder charges ...no ejector marks, primers are still round...but look at the primer cup it begins to extrude into the firing pin hole, this happens at 80,000 psi and about the only pressure sign. The other is stiff bolt lift, then your 80,000 plus with these cases as the do not deform like brass.
Have a go gauge to check lug set back, set so it has a slight resistance when closing...then any set back will be felt...check it often.
Seating depth is critical, just .030" COAL makes a big pressure spike...do not seat into the rifling, this causes a huge pressure spike 7,500 or more psi depending on the variables, like bearing surface of the bullet. There is a lot of extra caution that must be adhered to when indulging in this endevor.
Powders, most ordinary 308 powders will work with the 168 gr SMK type, I run tbe 169, and 177gr. For higher velocities the 200 gr & 2000 MR, for 208 to 230 gr 6.5 Staball, these powders work in brass cases as well.
I was hoping all would be worked out and new world of hybrid cased cartridges would be available, for all.
After all the military ran hybrid cases in machineguns, should be able to work them into a bolt action rifle. The reason load information isn't stated is... people. Rush out and throw the same powder charge in their cartridges without considering all the variables, that cause pressure spikes, plus different barrels, chambers, throats, COAL, seating into the rifling, bullet bearing surface and bullet makeup, all copper, jacketed lead, fmj, etc.
There is a nice improvement for the careful, attentive, experienced reloader...
Trying to be helpful, for those who want to try, but have no control over anything they attempt, as there is little room for error, with what we have to work with. Sig had over 60 powders blended for them tp test and it was top secret military stuff.
Also check the case OAL after the first firing...they tend to "grow" the first time before settling down.
And RL 26 and 140 to 153 is the key to 6.5 Creedmoor hybrid loads...

 

[tom12.7]

The hybrid cases I've converted to .308 and 6.5 CM have more case capacity than the brass cases I use for those calibers. I really don't have a way to know how high I've pushed the pressure up so far, but I feel I'm on the lighter side still. I have not had primer flow like what's pictured above and bolt lift has been easy. So far my loads have been more conventional pushed further than max listed loads, but not substantially so looking for other nodes, but have pushed almost 10% more in velocity in a few cases.

 

[st1650]

If there was an action I'd trust at 80K PSI it would certainly be my Nuke 2.0 or my Archmedes.

 

[tom12.7]

It would be about 13,500 pounds of bolt thrust, less than .338 LM. A lot of actions can safely handle that.

 

[45-90]

The hybrid cases I've converted to .308 and 6.5 CM have more case capacity than the brass cases I use for those calibers. I really don't have a way to know how high I've pushed the pressure up so far, but I feel I'm on the lighter side still. I have not had primer flow like what's pictured above and bolt lift has been easy. So far my loads have been more conventional pushed further than max listed loads, but not substantially so looking for other nodes, but have pushed almost 10% more in velocity in a few cases.

Yes the hybrid cases usually have more capacity my 308 are 57.8 gr H2o and 6.5 CM 52.3 gr H2o. The primers are still round, but the extrusion started at the higher pressures. Easy bolt lift is a clue, but it also depends on the action. These cases generally show no usual pressure signs, even though they are quite high.
10% velocity increase IS probably there...never exceed 3 grs over max on the Hodgdon Annual Manual for the exact bullet and exact COAL.
Pressure is a bad guesstimate. And any changes results in pressure changes ...just seating the 308 from 2.860" to 2.830" can put you over the 80,000 psi mark.

 

[z987k]

Yes the hybrid cases usually have more capacity my 308 are 57.8 gr H2o and 6.5 CM 52.3 gr H2o. The primers are still round, but the extrusion started at the higher pressures. Easy bolt lift is a clue, but it also depends on the action. These cases generally show no usual pressure signs, even though they are quite high.
10% velocity increase IS probably there...never exceed 3 grs over max on the Hodgdon Annual Manual for the exact bullet and exact COAL.
Pressure is a bad guesstimate. And any changes results in pressure changes ...just seating the 308 from 2.860" to 2.830" can put you over the 80,000 psi mark.

I'm always amazed at how people don't put COAL as part of their load. It's vital and small changes change the pressure a lot.
I mean, really it's seating depth, so you need the bullet length and coal to work it backwards.

 

[45-90]

Found a powder with super high velocity for a 308 177SMK 2.830" COAL hybrid case but not for ARs. I will have to confirm it. .545 BC bullet shoot it in the 22" barrel..over 2900 fps? Maybe.
Kinda like the 300 WM and 200 gr SMK bullets at 3280 fps...it was 80 feet faster than expected and stiff bolt, but the brass held...not a load I want to repeat. But the 230 gr SMK at 2962 fps were accurate and fast....workin with the 45-90 win for awhile. Then the 510 Whisper and a slower twist 8.6 blackout, when the barrels arrive for machining.

 

[45-90]

Curious what powders you're finding applicable for .308? I'm going back and forth on ordering a box or 2 of the hybrid cases to tinker with, and .308 would be the first to run it in, with 175-178 class projectiles to start. Currently running a shade over 2600 out of a 20" howa with 178 eldm, varget, and LC LR brass. Even if I stay at this pressure level the hybrid cases should theoretically last as long or longer than lapua small primer and are a good bit cheaper currently. As for venturing above, I'm not sure I can cram much more varget in them without belling the seating cup on my forster mic seater. Cfe223 and LVR would be my next 2 guesses, but LVR seems to get awful spiky at top end in 6arc.

I run 147 eldm at 2900 in 6.5cm with RL26 for a hunting load. Same benefits should apply there, but I dont have a neck turning setup and assume you'd probably need one to deal with the extra from necking down there...so 308 would be the first I tinkered with. Should be able to just run it in a mandrel sizing die and trim there though I'd think.

Completely understand if you don't want to put the info out there, never know who will just grab it and run without knowing what they are doing. PM would work, and if not, completely understand. I still may get some, measure volume, and tweak GRT to match velocities.

The Forester Mic seater is weak, I machined a new part for the 6 dasher as it swaged out.
You will need something more robust for these 50 plus grain loads. I like Hornady seaters heavy enough to machine and use the bullet point to lapp the seater in to the bullet point in the lathe...so compressed loads are not a problem. I have moved away from Lapua SR brass and prefer Lapua LR last time out with 230 gr SMK the best accuracy with these loads at 100 yds was hybrid brass, followed by Lapua LR, the bottom on of accuracy and largest S/D was Lapua Palma SR...I have used them alot in the past but no more....lower velocity & and higher S/D with worse accuracy, at least in the 230 gr loads.

 

[Woodenyeti]

Those who venture into the 80,000 psi hybrid case must not be beginners. First it's not recommend for anyone...the cases were not reloadable, no dies, available...forget firearm warranty, etc.
But sometimes we have to challenge the narrative.
I found the cases reloadable with the various factory dies, 4 times so far...on other projects now. But here is the basic information. The cases are hybrid, powder energy in the form of heat to the case is much less...where does the energy go ...into velocity most likely.
You are not fucking around here this is very serious shit, at 80,000 psi everything matters.
You must know the exact water volume of your case period... I own my reamers and the chamber barrels...I do not have someone "spun up" anything, immature slang, that describes nothing.
You must chronograph. And pressure signs are not prevalent, like on brass cases. These cases appear they will take 100,000 psi, but your rifle may become a grenade in your face, or pieces of SS case head.
Here are some 308 cases marked with powder charges ...no ejector marks, primers are still round...but look at the primer cup it begins to extrude into the firing pin hole, this happens at 80,000 psi and about the only pressure sign. The other is stiff bolt lift, then your 80,000 plus with these cases as the do not deform like brass.
Have a go gauge to check lug set back, set so it has a slight resistance when closing...then any set back will be felt...check it often.
Seating depth is critical, just .030" COAL makes a big pressure spike...do not seat into the rifling, this causes a huge pressure spike 7,500 or more psi depending on the variables, like bearing surface of the bullet. There is a lot of extra caution that must be adhered to when indulging in this endevor.
Powders, most ordinary 308 powders will work with the 168 gr SMK type, I run tbe 169, and 177gr. For higher velocities the 200 gr & 2000 MR, for 208 to 230 gr 6.5 Staball, these powders work in brass cases as well.
I was hoping all would be worked out and new world of hybrid cased cartridges would be available, for all.
After all the military ran hybrid cases in machineguns, should be able to work them into a bolt action rifle. The reason load information isn't stated is... people. Rush out and throw the same powder charge in their cartridges without considering all the variables, that cause pressure spikes, plus different barrels, chambers, throats, COAL, seating into the rifling, bullet bearing surface and bullet makeup, all copper, jacketed lead, fmj, etc.
There is a nice improvement for the careful, attentive, experienced reloader...
Trying to be helpful, for those who want to try, but have no control over anything they attempt, as there is little room for error, with what we have to work with. Sig had over 60 powders blended for them tp test and it was top secret military stuff.
Also check the case OAL after the first firing...they tend to "grow" the first time before settling down.
And RL 26 and 140 to 153 is the key to 6.5 Creedmoor hybrid loads...

Thanks for all the info, I've been curious about those cases since I first saw them available a few months ago. I've loaded lots of stuff over the past few years carefully, but the farthest off book I've been was figuring out running bolt gun 300blk subs with unique for super quiet loads. Didn't want to be the first to try the hybrid cases but was thinking somebody had to have explored it by now.

As far as oal greatly affecting pressures, I learned that the hard way to find your lands with a given projectile first with 243 in ar10. Went from a good load to popping 2 of 5 primers by loading a bit longer assuming I couldn't put a 103 eldx into the lands at well under mag length. Now with a new gun I generally find the lands with each bullet I plan to run and write it down before I even start working up loads. I also take 10 cases, fill them with high proof isopropyl to measure volume (less surface tension/bubbles) and calculate h2o volume from there. GRT is usually pretty darn close with as many variables accounted for as possible.

I'm only loading at 2.810 currently for my 178 eldm varget loads. Lands in my howa were right at 2.960 I believe, but that length is shooting pretty good and may still work in my gas gun too. I'm not interested in pushing pressures much higher even in my bolt gun, but additional case life is always welcome, as long as case volumes and ignition are still consistent. In this project I'd likely explore something closer to the lands with the bolt gun and take advantage of the additional case volume from both loading longer (but not into the lands) and the extra volume from the hybrid cases to keep pressures in check.

Thanks again for the info, I feel better knowing I wasn't the only one with the idea, and it has been attempted very carefully with good results.

 

[Eric_F]

Welp. I formed about 35 Fury cases down to 6.5 CM without too much issue. However, I found I needed a Small Base die and repeated sizings to get them fitting in a chamber gauge (or my chamber). But just today I started having cases where the brass was spinning separately from the steel base, and then had one separate inside my SB die. Yes it was lubed with lanolin, but maybe should have had more. Obviously I'm tossing the cases with the two parts spinning separately now.

I'll work on getting this out, tapping it and pulling is the usual approach, right? Much less metal to grab onto than a usual stuck case, so this die might be done for. Is anyone else having trouble forming 6.5 CM (or 308) from these hybrid cases?

 

[45-90]

Nope no trouble, but, it appears you are. I do both 308, 6.5 CM , & 358 Win.
I have posted information on necking up to other calibers including pictures. Same is true for necking down. No ones follows directions that work but always do it there own way...which is fine if it works.
Since I form a lot of cases including wildcat calibers I've learned a few things, plus make forming dies when needed.
You stop at the the first sign of trouble instead of continuing on, ruining cases...begs the question should you be doing this? What happens if you ignore pressure in load development just once?
Formed cases do not seperate and,/ or spin around, those are trash and I wouldnt put high pressure into any of them. Start over or quit, 80,000 psi is nothing to mess with in a haphazard manor.
Your cases should be solid one piece, just like the orginial 277 when finished.
So first use the "Lee Reresizing lubricant", it much better than lanolin, which works poorly in case resizing operations.
After lubing with the Lee stuff (follow directions) sorry, but you sound like a fuckin moron, and I'm old school. I don't care about your feelings but am concerned about your ass, we can be friends later...
Next use the standard 308 die to move the bulk of the shoulder to just above finish 6.5 CM .
Moving a 20° shoulder in brass, is easier than 30° or 40°.
Then run through your 6.5 FL CM die, with the Lee lube of coarse, but leave the small shoulder area free of lube as some dies do not have a hole drilled and lube dents occur.
Look at the picture this is how I do it, very easy no hassles follow directions, equals perfect results...the stuck case will need special attention to get it out, a regular stuck case remover will not work as the case head appears to be pull off. Carefully measurement of what's left in material and and a ultra fine pitch tap dead center without hitting the die body, as the hybrid brass is thin.
Buy a new cheap sizing die.
Or continue with doing it your way...
But I did take the time to show and explain the way that works, with little effort...and maybe help others doing this...becareful, loading these.

 

[Eric_F]

I can handle being called a moron, especially when paired with good advice. I am new to wildcats, unless you count fireforming 6 BRA, which shouldn't count. Not new to reloading at all.

I'll try the Lee lube and 308 die, thanks.

 

[45-90]

I can handle being called a moron, especially when paired with good advice. I am new to wildcats, unless you count fire orming 6 BRA, which shouldn't count. Not new to reloading at all.

I'll try the Lee lube and 308 die, thanks.

That's to get your attention....like a USMC drill instructor, to a new recruit. So maybe, if you follow instructions, you too will be successful at case forming, with full strength cases...cause they will be running at very high pressures,... well above normal. So if you are going to pursue this, I want you to be successful, and Safe, while benefiting from this new development. This method is very easy and has produced excellent cases. So it will work well for you too, pass it along to others who care to listen.
You are welcome...maybe, friends later.

 

[Eric_F]

Sorry to continue the thread drift, but in case it helps anyone I want to follow up: annealing my cases after forming fixed the issues I was having.

Pretty sure the work hardening after forming to 6.5 CM was preventing the last ~0.005" of shoulder set back. After one pass each of 308 and 6.5 CM dies, annealing, then another pass in 6.5 CM got headspace perfect.

Then neck turning is necessary given how thick the brass is, not sure how 45-90 apparently isn't neck turning unless he has a custom reamer. But given the work-hardened neck I think I was getting galling on my turning mandrel, causing the two crimped pieces to start spinning separately. Annealing after forming fixed this too, the neck was softened enough to expand better prior to turning.

And in case anyone is concerned about the softness of annealed brass, there are some interesting results here showing hardness return to as fired after just a bump resizing:

 

[45-90]

I do not anneal the 277 hybrid to 6.5 CM case forming operation... but neck turning into the shoulder is more than good practice. Safety concerns, as the neck thickens. And I'd advise to do so, but there are those who will not follow that practice
I use a metal lathe and diamond ground carbide tool with case radius honed into neck shoulder juncture.
So for those who insist on not doing it...it can be done with out neck turning, ...but that depends on the rifle, and neck clearance available, tighter neck chambers could have a
big pressure problem.
So with that, load a few cases to "normal" 6.5 CM pressures, fire them in your rifle, if a .264" bullet falls to the bottom in all cases, then your probably okay to go higher...But if any have interference or are snug, or do not drop through the case neck...STOP ...do not continue without neck turning. Safety is a main concern here. And an "intelligent" person would neck turn, as there IS a thicker portion as one goes down the neck.
But anneal away, if it suits your loading practices, and report on how that's working for you. That may help others with similar problems. Adopt what works for you.
I do anneal, just not here, It may be necessary for others to do so, with their dies and the loading proceedures...

 

[45-90]

See...Sometimes I anneal, after every forming operation, cause it's Starline 6.5 grendel basic, notice no head stamp on the cases. These will be 6 mm ARC when cases were impossible to find.
And starline says on their website, the cases are left hard and must be annealed.
I tested that statement...Starline was correct, without annealing the first case split down the middle, and cracked like glass. So the test proved I had to anneal...got 249 good ones out of 250 cases...

 

[45-90]

But many times I don't anneal or lube cases when forming ....when using my own forming dies. The secret is in the die making, probably worth a few million dollars
Here is an old 270 win pulled out of the scrap bucket, No lube just put in the shell holder and pull the press handle all the way. 3/4" formed 270 Win to 8.6 blackout, no lube no annealing with perfect shoulders. Cut off the excess in the Bridgeport mill in a one second plunge cut, then lube and run through a 8.6 blackout FL die.
Definitely have to neck turn here...but no annealing.
The ideas for the dies came when I was making them...what if. Scrap what I had already done or improve the case forming operation...it drastically improved the csse forming operation.
Been machining for 50 yrs, most in the nuclear, defense, aerospace, later computers, and robotics.
Refueling nuclear reactors commercial use, and weapons grade material for bombs.
My best invention was the end cap design that allowed the spent fuel rods to be pulled from the reactors core during refueling. Engineers spent months working on designing, internal and external, and I machined them all..then they called and ask if I had any ideas to submit...
In one week I had the working prototype. Westinghouse Nuclear fuels division sent out an order for 1.375 million zirconium parts.
The company I worked for made millions, and I got a small bonus, which I almost never got, as a machinist signs an agreement with the company that all his ideas and inventions belong to the company, while working for them and can not start a company with those inventions. But you keep your job, and a small bonus is a good thing...plus a travel case and gold quality pin from Westinghouse, with their logo...and a letter of appreciation...priceless...LOL.
It is, what it is.

 

[MK20]

@45-90 Thanks for your info here and on LRH. I am looking to start working with these hybrid cases and I am excited by what seems possible in a good setup.