Huh?
- Thread starter Matthew488
- Start date
Something like this?
www.rockriverarms.com 
LAR-BT6 .338 Lapua Magnum
Rock River Arms, Inc. offers a complete line of American made, custom built AR15 style rifles.
I've decided on 7mm Sherman Short Tactical for my build. Now I need to get the barrel ordered. How long and heavy profile will the AR10 platform support? The shop I'm going through does up to 27in.
I wonder about extraction on it, and feeding... Have you found others that have successfully built AR10s around this cartridge?
Barrel length is whatever you want it to be but there are sharply diminishing returns. The difference between 26" and 27" may be in the realm of 10-20 fps. .936 I think is about as wide as you want to go too but a gun that tips forward on a bipod is going to be pretty awkward to shoot so do the math on weight distribution.
-Alex
Last edited:
Richard Sherman stated that the 6.5 SST has been run in an AR10 and that the 7 SST would be about the same.
The Sherman cartridge appears to be slightly shorter than the 7 SAUM as far as mag length issues.
What about the .277 fury cartridge? 26” barrel and a heavy bullet?
I don't know anything about these but APF makes a MLR Carbon 300PRC semi-auto.
MLR - Carbon Fiber
APF Armory, Your Hometown AR Builder, 100% American Made AR15 rifles and parts
www.apfarmory.com ^I've read good things about APF but have no direct experience - maybe some others will chime in.
There's no such thing as a elr cartridge for an AR-10. As a elr cartridges would not fit in an AR-10 LOL
AR-10 chambered in 338 RCM shooting 300 gr Bergers from a 36" barrel 
25 Creed Berger 135 supersonic to around 1500 yds - probably best ballistics for the AR10 std bolt face and COAL.
For 1500 and beyond , the size of the projectile becomes just as important as the numbers on paper because a true ELR cartridge has an advantage of spotting hits and misses on all types of terrain.
My point was that ELR is not just having the ability to shoot 1500 yards it's having the ability to be consistent and quite possibly see impacts to ELR distances for example 3,500 yards some matches last year went over 4,000 yd and some coming up this year will most likely go to 5000 yd. So if you don't have the equipment caliber or cartridge to be shooting the full extent of a ELR match then you are not shooting e l r
So if you don't have the equipment caliber or cartridge and Skill to be shooting the full extent of a ELR match then you are not shooting e l r
Last edited:
And matched up with a LWRC REPER MKll Elite, just pure golden when pushing distance in the AR world. At a price like anything in the ELR world. Just saying, but yes we have seen a few customs running the big stuff but rare.except the 6.5 creedmoor
JH
agreed, OP said in the OP he just wanted something to stretch our an AR-10 platform as far as possible. I think a 6.5cm would be close to the best an AR-10 platform has to offer when trying to push to the limits within reason
E l r as a sport was defined as starting at 1500 yd and going Beyond so if whatever you're shooting can shoot at least 1500 yd you are shooting a e l r distance as defined by the sport. However owning something that can shoot up to 1500 yards are just passed 1500 yards doesn't really qualify as an ELR cartridge. I understand stating this is ELR for me or this is ELR for this cartridge. but that's like a dude identifying as a woman.
You do realize I stated 2500 yards in the post you quoted right?
I just picked up my AR10 barrel yesterday. Chambered in 7mm Sherman Short Tactical, 27" long heavy profile, 1:8 twist. Built on an Aero Precision M5 enhanced builders set.
I still have to save up for glass but will hopefully run over the chronograph next weekend at least. Time will tell on how it performs out to a mile or more.
I still have to save up for glass but will hopefully run over the chronograph next weekend at least. Time will tell on how it performs out to a mile or more.
What bolt and who cut the barrel for you? Thought I was going to do a 25 Creed myself, but much prefer an SST...
BCG is from KAK. I had Mostek make the barrel for me here in Mesa, AZ. Very good people to work with.
KAK upper as well? What's your barrel length, and do you have any loads worked up yet? Are you limited on 180's/184's due to COAL? I'm looking at 25, 6.5, and 7 SST, all running heavies, and while all of the bolt gun data is well documented, AR stuff is harder to find. If the 7mm can be seated far enough out to get a full charge, I like this option, especially since it should perform better out of a shorter barrel than either 6.5 or 25.
Both upper and lower are Aero Precision, 27" heavy profile barrel, adjustable .930 gas block. I'm planning on running 180gr ELDMs at least to start off with since that's what I'm running in my 7mm Rem mag.
It will be a little while before I can get glass so can't really work up a load yet but will hopefully run a few rounds over the chronograph this weekend.
It will be a little while before I can get glass so can't really work up a load yet but will hopefully run a few rounds over the chronograph this weekend.
Cool, please advise velocities with the 180's when you have them - wondering if you're going to start crunching powder due to shorter COAL. If so, I may go 6.5 or even 25 instead of 7.
Shhhh, don't tell them.
Because the case that will be available to reloaders will be limited to standard pressures, not the 80k psi that the military case is rated for limiting velocity. Not a bad long range setup but still not an ELR cartridge.
Omg, I keep hearing this, and it's so false. I don't know where it started, and why people keep repeating it.
As far as I've seen, there are no good target shooting projectiles for 6.8. The 6.8/270 caliber space is dominated by just hunting bullets. The 135gr FMJ that is coming with the Fury ammo that Sig is selling on their site isn't really optimized for long range target shooting.
While I agree 277 Fury isn't an ELR cartridge, the top part of the bimetal cases (the 80K+psi cases) is brass which is what is mostly getting touched in a resizing die, so I await to see if those cases are reloadable.
I definitely stand corrected on this but would not have thought it to be the case due to legal issues that could arise with current receivers.
If the case is useable I would love a shorter bolt action and wouldn't hesitate to run a Berger 170 EOL.
There are two types of ammo coming out for the Sig Spear. The 135gr is just conventional ammo without the hybrid case, and runs at normal pressure. The other is the hybrid case, higher pressure, and is using the Nosler 150gr ABLR. Not a match bullet, but still a long range bullet.
As of right now, it is not reloadable. Sig said they are exploring ways to make it reloadable, but there's currently no shell holders for it, or any data. One may not even care to mess with it though. It's going to be factory way hotter than anything anyone has been able to hand load for short action. The civilian version is going to feature a 16" barrel to start. The muzzle velocity tested on the 13" is already 2900 fps. That's about what I was guesstimating I'd be able to get out of my 20" 142gr 6.5cm, which I never got around to getting all the equipment for, and now I'm no longer even going to pursue.
Last edited:
The AMU did a lot of work with this idea back in 2010. https://www.shootingtimes.com/editorial/longgun_reviews_st_ar10ultra_062309/99358
I still don't see how an 80k psi load/brass is going to be available commercially. I can see lots of legal issues arising from completely misunderstanding what's in the box or someone using standard practices in reloading to check for pressure and grenading a barrel and receiver.
You haven't done enough research. You wouldn't say something like that, if you've looked around, and checked out the specifics. The ammo is already listed on sigs website. It's out of stock, but it's listed. Purchasers of the limited edition mcx already received a box of both standard and higher pressure ammo. The cases are quite distinct from each other, and clearly identifiable.
It seems moot anyway - the projectiles aren't great in 277 vs either 264 or 284, and the higher pressure doesn't add that much velocity compared to any of the many available larger cases. Perfect example is the SST discussed above - destroys the Sig cartridge ballistics in either 7, 6.5, or 25. Not to say higher pressure cartridges in general won't raise the bar, just that being an early adopter here nets you nothing.
That SST does not destroy the sig .277 fury in relation to muzzle vocity per barrel inch. That gun is like 4 1/2 feet long! Look at it leaned up against that refrigerator and see how high it touches, then place yourself next to that fridge and realize how big that gun is. If you're going to use that as an example, well then it's the exame of what is "moot" because you might as well just get a Barrett .50BMG. What that gun is boasting is not the point of what's trying to be achieved out of a short action semi-auto.
I mean it's not even out on the market yet, why would there be such a vast support for it at this point?
C'mon scro! Don't see why so personally involved in the cartridge - objective facts contradicting a belief should change that belief rather than elicit anger and illogical retort. SST has ~15 grains more capacity and can run lighter or heavier, all with much better BC than 277. Or go WSM or SAUM or PRC etc. Better ballistics all day in any rifle config. 1+1 can't equal 9 unless you're a leftist
7 PRC was leaked in what, August and the entire shooting world has blown it up.
Sig Fury was announced in 2019 and there is zero support beyond Sig. Why? For the reasons I already stated.
Uhh, ok first of all, there was nothing in my post that suggested anger, it's just called debate, and second of all, nothing I said is based on a belief. The Sig MCX is a AR-10 size frame with a 13" barrel, let me say that again, a 13" barrel, sending a 150g .277 caliber projectile at 2900 fps.C'mon scro! Don't see why so personally involved in the cartridge - objective facts contradicting a belief should change that belief rather than elicit anger and illogical retort. SST has ~15 grains more capacity and can run lighter or heavier, all with much better BC than 277. Or go WSM or SAUM or PRC etc. Better ballistics all day in any rifle config. 1+1 can't equal 9 unless you're a leftist
Similar threads
