New 6mm Advanced Rifle Cartridge

Ledzep

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    That chart that is out there that has MV vs. barrel length with a red trend line is real world (Labradar) data from a barrel cut down test w/factory ammo.
     

    willbird

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    I had just spot checked a few of the Hornady velocities at shorter lengths and it looked close, but moving out towards 20" I see what you are saying.
     

    tomcatfan

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    My 21" Odin works barrel gets 2740 with their factory 108 eld ammo and it hasn’t broken in yet. Their numbers seem low, which is a good thing IMO.
     

    5RWill

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    Bullpups are one of those great ideas that fall apart (for me) when they meet reality. I own quite a number of them, and this is obviously different for everyone, but ergonomically you are trading off a lot to get that short OAL. I love the weight balance, love the OAL vs. barrel length, but they are awful to deal with stoppages/mag changes/etc, even with a lot of practice. Most of the triggers are mediocre at best, and awful at worst - even the aftermarket triggers. Even though I've got a bunch, they rarely go out anymore, I'd rather lose some velocity with the shorter barrel and make up for it with ergo/trigger/etc.

    With the MDR/MDRX, make sure to go look up the reviews regarding reliability; it's no AUG.
    I have that was the gen I and apparently has been rectified. I do understand where you’re coming from they’re different. And the triggers usually suck but if the trigger is half as close as the SRS I’ll chance it. The SRS trigger is phenomenal.

    For what i want out of it though which is hunting/truck gun and target plinking it fits the bill perfectly even if it might require a little work on my end. My SHTF rifle is a 11.5” 5.56 if the need ever arises
     
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    ormandj

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    I have that was the gen I and apparently has been rectified. I do understand where you’re coming from they’re different. And the triggers usually suck but if the trigger is half as close as the SRS I’ll chance it. The SRS trigger is phenomenal.

    For what i want out of it though which is hunting/truck gun and target plinking it fits the bill perfectly even if it might require a little work on my end. My SHTF rifle is a 11.5” 5.56 if the need ever arises
    I had an SRS A1 Covert, too. Sold it for ergo reasons, no major issues. The trigger was great for a bullpup but it wasn’t a TriggerTech Diamond. ;) They definitely have their place and if the ergos work for you awesome!
     

    Yondering

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    That chart that is out there that has MV vs. barrel length with a red trend line is real world (Labradar) data from a barrel cut down test w/factory ammo.
    With one of the powders on the list, maybe. Look at the chart closer and compare the numbers, it's pretty clear the extrapolated (at best) all the other powders from whichever one they tested. I'm betting their test was only one sample as well, with an apparently very slow barrel. The velocity numbers in that chart seem to be at least 200-250 fps* slow compared to a good barrel.

    Part of my profession is analyzing data like this. Just because it's published data from a reputable company (and I do like Hornady as a company) doesn't mean it's good data. When you see red flags in the data like on that chart, it's wise to do more research before accepting it.

    *Edit: I have to retract my statement about velocity - I was looking at the wrong line for Lever numbers like a moron. I still think they might be a little on the slow side for that charge weight, but within 50-100 fps, not 200-250. Sorry about that.
     
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    ormandj

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    With one of the powders on the list, maybe. Look at the chart closer and compare the numbers, it's pretty clear the extrapolated (at best) all the other powders from whichever one they tested. I'm betting their test was only one sample as well, with an apparently very slow barrel. The velocity numbers in that chart seem to be at least 200-250 fps slow compared to a good barrel.

    Part of my profession is analyzing data like this. Just because it's published data from a reputable company (and I do like Hornady as a company) doesn't mean it's good data. When you see red flags in the data like on that chart, it's wise to do more research before accepting it.
    It blows my mind a company of this size would release data without basic statistical analysis expertise. If the load data and velocity data is single sample, that is beyond baffling to me. I would expect the velocity curve would be from the highest performing/suggested powder if only one was given, but definitely as an average across multiple shots. That said, I would also have expected all of the powder options to be mapped. What’s the cost, while cutting down the barrel, to run through a few test cartridges in each powder vs. just one? I would not expect multiple barrels, though it would be nice.

    I’m still surprised at the lack of some powders from the chart. For a new cartridge, I’d expect all of them with the appropriate burn rate and properties to be tested. I’m glad they tested more than I’ve seen for some other cartridges, but why not all? Surely in comparison to the cost of standardizing a cartridge it isn’t cost. What’s a few thousand rounds and a few dozen pounds of powder?

    I’m still waiting on my 10.5” Bartlein barrel, hopefully it will arrive soon so I can run my own tests and compare to an 18” Bartlein produced on the same reamer to the same specs. I can’t test the barrel lengths between these two, but it’ll be interesting to see the delta.
     
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    Yondering

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    It blows my mind a company of this size would release data without basic statistical analysis expertise. If the load data and velocity data is single sample, that is beyond baffling to me. I would expect the velocity curve would be from the highest performing/suggested powder if only one was given, but definitely as an average across multiple shots. That said, I would also have expected all of the powder options to be mapped. What’s the cost, while cutting down the barrel, to run through a few test cartridges in each powder vs. just one? I would not expect multiple barrels, though it would be nice.

    I’m still surprised at the lack of some powders from the chart. For a new cartridge, I’d expect all of them with the appropriate burn rate and properties to be tested. I’m glad they tested more than I’ve seen for some other cartridges, but why not all? Surely in comparison to the cost of standardizing a cartridge it isn’t cost. What’s a few thousand rounds and a few dozen pounds of powder?

    I’m still waiting on my 10.5” Bartlein barrel, hopefully it will arrive soon so I can run my own tests and compare to an 18” Bartlein produced on the same reamer to the same specs. I can’t test the barrel lengths between these two, but it’ll be interesting to see the delta.
    Notice how every single powder in the chart loses exactly 395 fps between 24" and 12".

    I'm sure they tested multiple samples of that one powder (whatever they used), but by single sample I meant only one barrel. I don't know that for a fact, but I think it's a pretty good guess; they're probably just trying to get some preliminary safe data out there and don't want people going too nuts chasing speed.

    I do have to retract my earlier statement though about velocities - I was looking at the wrong line for Lever numbers. I still think they might be a little on the slow side for that charge weight, but within 50-100 fps, not 200-250. Sorry about that.
     
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    Dino11

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    2.22" is what the newer lots are.
    The new OAL for the 105's is 2.200, I have been in the reloading room all morning loading some of them. I am loading Nossler 105's, I have some of the Hornady 105's but those things make me want to pull my hair out. I have a tight chamber Odin barrel that loves the Nossler RDF and 29.4gn of Leverevolution. Shoots sub .5 MOA @ 100 yards with them. Hornady has the load data on their site and it also reflects 2.200.

    I want to add though that I do not load using OAL, but use a Comparator to get my length, but I did measure a factory load this morning just because I guess. And I always use my OAL guage before starting a new load as things change a little sometimes. I want my lead jump to be in that sweet spot. Well got to get back to it, got 300 rounds to load.
     
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    MTxTwelve

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    Thank you for the information @Dino11 and @Ledzep - does Hornady have that published anywhere? I've seen 2.185" tossed around as well, just nothing from Hornady on this.

    Regardless, pretty anxious to see how this will do from a 22" barrel.
     

    Dino11

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    Thank you for the information @Dino11 and @Ledzep - does Hornady have that published anywhere? I've seen 2.185" tossed around as well, just nothing from Hornady on this.

    Regardless, pretty anxious to see how this will do from a 22" barrel.
    Minimum SAAMI spec is 2.135 to a max of 2.260, but you do not want to load the Hornady 105's past 2.200. The profile of the bullet will push it into the lands and jam it in their. Any of the other heavies can be loaded all the way to 2.260. I load the Nossler 105 RDF's to 2.215, they are a different profile than the Hornady's, they are a little longer but skinnier so they don,t contact the lands. Here is some load data for you. Hornady's site has the 108 data on it, I don,t have it on this computer but it is the same as the 105 data except the OAL is 2.245, found it and added.
     

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    Yondering

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    Minimum SAAMI spec is 2.135 to a max of 2.260, but you do not want to load the Hornady 105's past 2.200. The profile of the bullet will push it into the lands and jam it in their. Any of the other heavies can be loaded all the way to 2.260. I load the Nossler 105 RDF's to 2.215, they are a different profile than the Hornady's, they are a little longer but skinnier so they don,t contact the lands. Here is some load data for you. Hornady's site has the 108 data on it, I don,t have it on this computer but it is the same as the 105 data except the OAL is 2.245, found it and added.
    Guys, if you want the OAL to be "in that sweet spot" you really need to test groups at different OAL in your rifle. Don't make the mistake of assuming the factory stuff is at an optimum OAL.

    Also, learning how to find the max OAL for your chamber is important and is the first step before you ever charge a case with powder. Don't just go by the numbers in the manual or whatever factory ammo is.
     

    Dino11

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    Guys, if you want the OAL to be "in that sweet spot" you really need to test groups at different OAL in your rifle. Don't make the mistake of assuming the factory stuff is at an optimum OAL.

    Also, learning how to find the max OAL for your chamber is important and is the first step before you ever charge a case with powder. Don't just go by the numbers in the manual or whatever factory ammo is.
    The chamber on my barrel is on the tight side y .006 under the spec for it. Load development was quite challenging at first. But after detailed measurements were taken and alot of different bullet lengths and lead jumps tried I have finally got a pretty good hand on this round. I have three barrels, two 18" and a 20". I have the Odin 18" and the Faxon 20" built into rifles, so I have to do loads for two seperate rifles. Last week at the range was the first time out for the 20". I kept my brass seperated and was going to do detailed measurments on the spent cases, but my son thought he would help me out and dumped all the brass into the ultrasonic cleaner and mixed it all together. I wanted to choke him, he made me so much more work because not only were there two guns, there was factory ammo shot as well as reloads.
     

    Yondering

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    The chamber on my barrel is on the tight side y .006 under the spec for it. Load development was quite challenging at first. But after detailed measurements were taken and alot of different bullet lengths and lead jumps tried I have finally got a pretty good hand on this round. I have three barrels, two 18" and a 20". I have the Odin 18" and the Faxon 20" built into rifles, so I have to do loads for two seperate rifles. Last week at the range was the first time out for the 20". I kept my brass seperated and was going to do detailed measurments on the spent cases, but my son thought he would help me out and dumped all the brass into the ultrasonic cleaner and mixed it all together. I wanted to choke him, he made me so much more work because not only were there two guns, there was factory ammo shot as well as reloads.
    Good info, but I may be missing how you meant it to relate to my comment (asking since you quoted it)?

    My point is, if you're looking for best performance, test different OAL in your rifle, don't just go by what the factory stuff is or what the manual says. The "spec" doesn't mean anything in relation to what OAL your rifle will shoot best with, and each rifle barrel is it's own beast. On top of that, you may want to adjust OAL as the throat wears, so knowing how to measure your max OAL with a particular bullet can tell you that info.

    Figuring out your max OAL is the starting point (sounds like you know how to do this I think but this is really aimed at MTxTwelve) then test loads in a range of ~.100-.150" leading up to that depending how thorough you want to be, and how much magazine constraints affect things. I've found that's actually more effective than searching for a powder charge node; often I've found the accuracy I'm looking for at a workable max load (meaning just enough under max to be useable long term for many reloads). If not, you've still found the best OAL, and can adjust powder charges from there.

    For example, in my 24" 243 LBC the max OAL for the 105gr BTHP is 2.260, so I ran an OAL test between 2.255" and 2.155" in .020" increments to start, then fine tuned from there. That test showed me the best accuracy was at 2.235" with a max charge of Lever. More importantly though, that OAL gave me good accuracy with mixed charges varying between 30.0gr and 31.4gr. I'm using 31.0gr for that load for best velocity and best accuracy but still retain good performance even if velocity drops a bit in cold weather, because that OAL shot well across that whole range of charge weights. (although fwiw I didn't lose as much velocity in the cold as I expected, but it doesn't get much below about 20° F here.) Charge weights for the 6 ARC are a grain or more lower of course, depending on the throat geometry, and your OAL will be different, but the same principle applies.

    One really nice thing with these cartridges is that mag OAL is not as much of a constraint as it is with other cartridges like the 5.56. Even my 6.5 Grendel likes most if it's loads around 2.300", but the 6mm flavor does well shorter than typical mag length. Of course that's one of the main reasons it's such a cool family of cartridges.
     
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    jbailey

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    One really nice thing with these cartridges is that mag OAL is not as much of a constraint as it is with other cartridges like the 5.56. Even my 6.5 Grendel likes most if it's loads around 2.300", but the 6mm flavor does well shorter than typical mag length. Of course that's one of the main reasons it's such a cool family of cartridges.
    100% agree with this.

    This is the major 'light bulb moment' that 6.5G was. 223/5.56 was a cartridge designed in another time before ballistics where as clear and present important; back then, bullets were not long and sleek, but short and fat, so you could have long and sleek brass. But once bullets became long and sleek, brass needed to change as well, to short and fat. 6PPC/6.5G/6ARC is that change. Added benefit: short and fat powder columns are probably inherently more 'precise' than long and sleek ones, meaning rifle precision increases as well.

    Love it!
     

    willbird

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    100% agree with this.

    This is the major 'light bulb moment' that 6.5G was. 223/5.56 was a cartridge designed in another time before ballistics where as clear and present important; back then, bullets were not long and sleek, but short and fat, so you could have long and sleek brass. But once bullets became long and sleek, brass needed to change as well, to short and fat. 6PPC/6.5G/6ARC is that change. Added benefit: short and fat powder columns are probably inherently more 'precise' than long and sleek ones, meaning rifle precision increases as well.

    Love it!
    IMHO the whole short/fat ctg thing has been totally blown out of proportion without any real scientific proof that one ctg shape is better than another. But the idea does sell guns, dies, and brass :).

    Ctg design is driven by the constraints of repeating rifles, an AR15 ctg can only be so long and so big around without changes to the original stoner design.

    In the instance of the 6mm arc we see a reduced maximum chamber pressure that was forced by the limits of the action design. We also see magazine issues driven by the constraints of the magwell, the same magazine design that works great with 5.56 the ctg the gun was designed around does not work well with 6mm arc dia cases. It is all negotiation and compromise :).

    Bottom line there is a HUGE market for any ctg/upper design that will just drop onto an existing ar15 lower....from 17 caliber to 50 caliber.

    Bill
     

    MTxTwelve

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    Good info, but I may be missing how you meant it to relate to my comment (asking since you quoted it)?

    My point is, if you're looking for best performance, test different OAL in your rifle, don't just go by what the factory stuff is or what the manual says. The "spec" doesn't mean anything in relation to what OAL your rifle will shoot best with, and each rifle barrel is it's own beast. On top of that, you may want to adjust OAL as the throat wears, so knowing how to measure your max OAL with a particular bullet can tell you that info.

    Figuring out your max OAL is the starting point (sounds like you know how to do this I think but this is really aimed at MTxTwelve) then test loads in a range of ~.100-.150" leading up to that depending how thorough you want to be, and how much magazine constraints affect things. I've found that's actually more effective than searching for a powder charge node; often I've found the accuracy I'm looking for at a workable max load (meaning just enough under max to be useable long term for many reloads). If not, you've still found the best OAL, and can adjust powder charges from there.

    For example, in my 24" 243 LBC the max OAL for the 105gr BTHP is 2.260, so I ran an OAL test between 2.255" and 2.155" in .020" increments to start, then fine tuned from there. That test showed me the best accuracy was at 2.235" with a max charge of Lever. More importantly though, that OAL gave me good accuracy with mixed charges varying between 30.0gr and 31.4gr. I'm using 31.0gr for that load for best velocity and best accuracy but still retain good performance even if velocity drops a bit in cold weather, because that OAL shot well across that whole range of charge weights. (although fwiw I didn't lose as much velocity in the cold as I expected, but it doesn't get much below about 20° F here.) Charge weights for the 6 ARC are a grain or more lower of course, depending on the throat geometry, and your OAL will be different, but the same principle applies.

    One really nice thing with these cartridges is that mag OAL is not as much of a constraint as it is with other cartridges like the 5.56. Even my 6.5 Grendel likes most if it's loads around 2.300", but the 6mm flavor does well shorter than typical mag length. Of course that's one of the main reasons it's such a cool family of cartridges.
    I appreciate the insight for optimal accuracy and agree that this is a procedure reloaders should follow, but I shoot factory ammo exclusively and it is why the "correct" OAL from Hornady is relevant to me. For me, factory ammo is not a limitation - I know that isn't a popular outlook on this forum, but it's the truth for me.
     
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    Yondering

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    IMHO the whole short/fat ctg thing has been totally blown out of proportion without any real scientific proof that one ctg shape is better than another. But the idea does sell guns, dies, and brass :).

    In the instance of the 6mm arc we see a reduced maximum chamber pressure that was forced by the limits of the action design. We also see magazine issues driven by the constraints of the magwell, the same magazine design that works great with 5.56 the ctg the gun was designed around does not work well with 6mm arc dia cases. It is all negotiation and compromise :).
    OK some of that is neglecting the obvious.

    Short fat cartridges are clearly better for allowing longer bullets to fit in a magazine.

    And the whole complaint about not using common magazines is absurd IMO. Do you use 9mm magazines to shoot 40 S&W in pistols? I would have thought using the correct mags would be obvious to anyone vaguely familiar with firearms, but it seems to be lost on some. Yes, more magazine development for this cartridge size can only be a good thing, but we already have a number of good options in Grendel mags right now that work well. I can only just shake my head and wonder at guys trying to use Pmags or USGI mags for the Grendel/PPC case size and talking about how the AR doesn't work well for other cartridges.
     
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    Yondering

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    While true, some don’t have the money or the time to invest into reloading. .
    That's a different excuse though, not what he said or what I responded to.

    Time is a valid reason, but the "not enough money" excuse is a lot like saying you can't afford to fix your own car so you pay someone else to do it. It's flawed logic unless you hardly shoot much at all.
     

    willbird

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    Not a "complaint" about magazines, just pointing out that when you run into that it shows you where the edges are that show you "go further and it will no longer work in this platform". The need to run a lower pressure is indicating that too. So it is not "absurd" to speak of those symptoms.
    The magazine issue was important enough to drive the development of the LWRC platform. But snap back to the idea of "there is lots of money in any system that drops onto existing AR15 lowers"..that leads as I said to negotiation and compromise. Lower pressures and special purpose magazines. Put the same round in a rifle that can handle 62,000 PSI and it will perform better. ...300 fps more muzzle velocity. So in the popular vernacular :) they "cut the balls off" the 6mm arc to shoehorn it into the ar15 platform :).
     

    willbird

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    If you got into reloading right now where would you get primers ?? I was born reloading pretty much. My dad liked to have a cast bullet solution for any gun he owned, some guns he owned that are now mine he never fired a single factory round from the day they were new. But to be able to reload if you shoot much you ought to be a hoarder of primers and powder pretty much.
     

    hlee

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    Primers are out there. Get on the notifications lists at your favorite vendors. I have a local shop that has primers, but is restricting purchase numbers.
     

    tomcatfan

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    That's a different excuse though, not what he said or what I responded to.

    Time is a valid reason, but the "not enough money" excuse is a lot like saying you can't afford to fix your own car so you pay someone else to do it. It's flawed logic unless you hardly shoot much at all.
    Shooting volume and rounds that you load for are both very important. I wouldn't recommend getting into reloading if you are only going to shoot 9mm FM and M193 ammo. It isn't cost effective to reload those unless you shoot tens of thousands of rounds. At the end of the day, it's different strokes for different folks.
     

    willbird

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    Oh they were always "out there" but the question is the price. They really do not go bad so might as well crack the slab when they are avail.
     

    tomcatfan

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    I got an email yesterday from Midwest saying my 6mm ARC ammo back order is in. It should ship soon!!! Now I wont' feel bad shooting...
     

    steve123

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    The question for some of us is "what ctg do you use in a 10.5"-12.5" barrel", the arc looks pretty darn good. Nobody proposed that it was a do all proposition. Chopping off 6" of barrel we only lose about 250 fps, 10% pretty much, hardly "cutting the balls off" ;-).

    Bill
    We can do this all day long Bill, yuh goofball you, lol.

    I gave you guys the benefit of the doubt by calling the 250 fps deduction a one baller, lol, but wait there's more...

    ONLY 250 FPS??!! Nope, according to the Hornady chart you posted there's a 400 fps reduction in velocity from 12 to 24". Now that's cutting it's balls off for sure, man there's practically a vagina now! Whatever, one baller or ball-less, if that turns your crank go for it.

    If my 6mmBR were going 250 fps less than it is now I'd take the barrel off and throw it on the scrap pile, lol. Or 400 fps less, now that's just heinous.

    In response to your other post, I already gave my answer earlier, 6.5G, 6.8 , or 300BO, make good "PISTOLS", because that's exactly what you are doing.

    Just be honest, the only reason people want super short barrels is because they need something to hang their suppressor off of. Nothing more, nothing less.
     

    Henryrifle

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    In an attempt to conserve my best primers, I am going to rework my best 6mm ARC and CFE223 load with CCI 400 primers. Has anyone had a problem with that? Does CFE223 perform significantly better with BR4s or 450s?

    Thank you,
    Henryrifle
     

    ormandj

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    In an attempt to conserve my best primers, I am going to rework my best 6mm ARC and CFE223 load with CCI 400 primers. Has anyone had a problem with that? Does CFE223 perform significantly better with BR4s or 450s?

    Thank you,
    Henryrifle
    It should be ok. The powder column is small enough it should ignite reasonably well. Worth a figurative and literal shot, at least. In .260 or something else larger, it would be a different story. If you see low ES/SD and the velocity you expect, you'll know you're good. Just make sure to re-workup loads when the temperature cools down, as you'd have to do anyways with CFE223.
     

    ormandj

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    We can do this all day long Bill, yuh goofball you, lol.

    I gave you guys the benefit of the doubt by calling the 250 fps deduction a one baller, lol, but wait there's more...

    ONLY 250 FPS??!! Nope, according to the Hornady chart you posted there's a 400 fps reduction in velocity from 12 to 24". Now that's cutting it's balls off for sure, man there's practically a vagina now! Whatever, one baller or ball-less, if that turns your crank go for it.

    If my 6mmBR were going 250 fps less than it is now I'd take the barrel off and throw it on the scrap pile, lol. Or 400 fps less, now that's just heinous.

    In response to your other post, I already gave my answer earlier, 6.5G, 6.8 , or 300BO, make good "PISTOLS", because that's exactly what you are doing.

    Just be honest, the only reason people want super short barrels is because they need something to hang their suppressor off of. Nothing more, nothing less.
    If you're only shooting at limited distances, like most of those of us who hunt do, why do you "need" that extra speed? I'd much rather a short and handy rifle (that I'm hanging a suppressor off) than a 24" + 7" suppressor monstrosity when hiking around. Pigs will be just as dead with the short barrel. Pick the right tool for the job.

    I've got an 18" and a 10.5" Bartlein on the way for exactly this reason. The 18" for the range, and the 10.5" for hunting. I'll take the two stamp special out to the range and update later with how it does. Even the 10.5" at 2250fps is still traveling at 1200 fps w/ a 108 ELD-M at 800 yards. With a 18" barrel at 2650 it'll hit 1200 fps around 1050 yards. That's an acceptable tradeoff to me for the ease of carry depending on the situation. I'm obviously going to shoot the 18" when at 1000yds (no promises I won't try with the 10.5"...)
     
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    Yondering

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    We can do this all day long Bill, yuh goofball you, lol.

    I gave you guys the benefit of the doubt by calling the 250 fps deduction a one baller, lol, but wait there's more...

    ONLY 250 FPS??!! Nope, according to the Hornady chart you posted there's a 400 fps reduction in velocity from 12 to 24". Now that's cutting it's balls off for sure, man there's practically a vagina now! Whatever, one baller or ball-less, if that turns your crank go for it.

    If my 6mmBR were going 250 fps less than it is now I'd take the barrel off and throw it on the scrap pile, lol. Or 400 fps less, now that's just heinous.

    In response to your other post, I already gave my answer earlier, 6.5G, 6.8 , or 300BO, make good "PISTOLS", because that's exactly what you are doing.

    Just be honest, the only reason people want super short barrels is because they need something to hang their suppressor off of. Nothing more, nothing less.
    You're being a hypocrite about this. I distinctly remember a conversation with you about the 243 LBC where you were happy to give up 300 fps so you could use the stick powder you wanted. Now you're acting superior to people getting the exact same speeds with half the barrel length? Get real man. If it wasn't your idea, it must be a bad idea, right?

    Also, name another other AR15 cartridge that performs as well at even just 500 yards from a 12.5" barrel without pushing so hard it destroys brass. Compare it to the 6mm 105gr BTHP @ 2400 fps. I'll wait; put up or shut up. Only competitor I can think of is the Valkyrie, but realistic short barrel numbers seem to be a bit behind if I'm not mistaken.

    And what's wrong with using a short barrel to use a suppressor on? You act like that's some BS reason that nobody really needs; why? You keep showing how much of your comments are just unfounded opinion that are only right because it's your opinion, never mind the facts.
     
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    Yondering

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    Not a "complaint" about magazines, just pointing out that when you run into that it shows you where the edges are that show you "go further and it will no longer work in this platform". The need to run a lower pressure is indicating that too. So it is not "absurd" to speak of those symptoms.
    Apparently 40 S&W pistols are "really pushing the edges" too, since they have to use different magazines. Yes, the whole complaint and discussion is absurd.
     

    Constructor

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    In an attempt to conserve my best primers, I am going to rework my best 6mm ARC and CFE223 load with CCI 400 primers. Has anyone had a problem with that? Does CFE223 perform significantly better with BR4s or 450s?

    Thank you,
    Henryrifle
    At 52000 psi those primers will be fine as far as not cratering and will ignite powder up to around 42gr without problems. BRX, Dasher, 6.5x47 and 308 small primer brass really need magnum primers to ignite that much powder...better results anyway.
     

    steve123

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    none of your business
    You're being a hypocrite about this. I distinctly remember a conversation with you about the 243 LBC where you were happy to give up 300 fps so you could use the stick powder you wanted. Now you're acting superior to people getting the exact same speeds with half the barrel length? Get real man. If it wasn't your idea, it must be a bad idea, right?

    Also, name another other AR15 cartridge that performs as well at even just 500 yards from a 12.5" barrel without pushing so hard it destroys brass. Compare it to the 6mm 105gr BTHP @ 2400 fps. I'll wait; put up or shut up. Only competitor I can think of is the Valkyrie, but realistic short barrel numbers seem to be a bit behind if I'm not mistaken.

    And what's wrong with using a short barrel to use a suppressor on? You act like that's some BS reason that nobody really needs; why? You keep showing how much of your comments are just unfounded opinion that are only right because it's your opinion, never mind the facts.
    Distinctly', I think not, and It's not 300 fps, it's only 100-ish fps more to use a temp F'ed ball powder vs temp stable stick powder. And yeah, it's a no contest, I'll stay with H-4895 summer and winter, and so keeping my first round hits. Touche

    You're the one that's constantly mouthing off in the semiauto forum, lol. Narcissistic much??!! Care to compare post count in the semi forum?? Touche

    Hypocrite, that's calling the kettle black, C'mon man open your eyes, lol.
    Here's your quote again showing your hypocrisy.
    Yondering, here's a quote from you back in post #36
    """""As much as I like the 6mm Grendel family of cartridges, IMO for a 12.5" I would choose the larger 6.5mm bore.""""

    Here I am putting up but not shutting up...

    I had to google a 123gr in a 12.5" barrel from a 6.5G and then I C&P'ed from a guys article - "Hornady’s 123-grain AMAX load was the slowest averaging 2,308 fps. This provides 1,455 ft-lbs of energy at the muzzle".
    Me- If that's the slowest factory load in this article then the 123gr can be driven faster, right?!
    Yawndering -since you are such a super duper max load aficionado I'll add 50 fps to give more brevity, let's say 2358 fps.
    So the 6mmART with 105's going 2400 fps, at 500Y, in a 10 mph full value wind, has, 2.4" less drift, the width of a pop can. BUT has 57 pounds LESS energy. At 400Y the two are almost the same. Yawndering, that's what you call MINUTIA. In other words this is such a stupid argument you are failing at!!!!!!!!!!

    I'm not going to look up 224V in a 12.5", it's a waste of time because it'll be much the same except even less energy.

    Here's my quoted posts that reveals exactly what I stated, showing how I "feel" about using pistol barrels for long range.
    #806 - Personally I don't get the short barrel thing using a cartridge like this when most everyone already has their 223's, 6.5G's, 6.8's, 300BO, etc.
    #859 - Me- I didn't say it was a bad idea using a pistol length barrel for 6ARC, just not what I would want to do. BTW here's another quote from Yawn - """If it wasn't your idea, it must be a bad idea, right?
    #871 - I'm not surprised at all but it's not what I would grab out of the safe for 500Y+ shooting.

    AGAIN, if you or anybody else wants to shoot 6mmARC in pistol barrels, with huge velocity losses, at farther distances, that's fine but I have no reason to and that is not hypocrisy or anything else but how look at the subject.

    Instead I'll stick with a medium load of 95gr SMK, at 2870 fps, in a 22" barrel, with H-4895 in my FatRat and do it how I want.

    Of course I have nothing against suppressors, it's the first thing I'd do if I was going to cut the barrel short/balls off!
    But you all know damn well that when you get a can the first thing you do is consider getting a shorter barrel so the can isn't poking into the next county. They go together like peanut butter and chocolate, cans and short barrels.
     
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    Henryrifle

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    I tested CCI 400 primers today VS the CCI BR4s I've been using and @ormandj and @Constructor were right! The primers worked fine and there was no real change in velocity. The CCI 400s were a little flatter but not pierced or even close. No hang fires or any other unexpected behavior. The MV was 4-5 FPS faster and SDs were actually better with the 400s.

    Target was shot prone at 100 yards using Harris bipod and rear squeeze bag. All groups were fired by single loading except the bottom right group which was magazine fed.

    A little more load development is necessary but this is a load that I can play with while continuing the less fun work. Barrel has 270 rounds through it as of today and there is some noticeable gas port erosion on the forward edge of the hole.

    Target 1.jpg

    Henryrifle
     
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    Bantam1

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    I am slowly gathering parts for my build but am undecided on barrel length. I see Altus is showing a 20" Proof for preorder, with a January ship date. For those of you that have more time behind these, what are your thoughts about going with an 18" vs. 20 or longer? I ran some numbers and see for my area the factory rounds doing 2630 in an 18" are still supersonic until 1100 yards or so. I am not sure if the extra length is worth it if the gain is only 20-30 fps. Finding real world velocity for some of the barrel lengths has been tough with the exception of a few here.
     

    SkyScrapin

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    Has anyone messed with the 18” carbon proof barrel? Curious how the velocity stacks against the rest of the barrel makers with factory Hornady ammo.
     

    SkyScrapin

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    I have been thinking 16inch proof becase i am going to keep a suppressor on it and would like a handy truck gun..
    I built an 18" proof 6.8, purely due to lots of ammo stock, but I could easily see another 18" proof 6 arc taking it's place. I run it suppressed as well.

    For a truck gun, I would go shorter, around 12.5 or 14.5". Much handier than this 18" gun, and you're really not giving up much inside of 400 yards.
     

    Henryrifle

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    @Bantam1: I imagine that 18" is a good compromise between velocity and weight + handling. While I don't think one size fits all, 18" seems like a good all-around solution.

    I didn't want a 24" barrel but I wanted to make sure mine would perform at 1000 yards and as I have a lathe and built my own barrel, I went with 21.75" thinking that I might reduce the length at some point. My barrel has sped up a little and is now shooting the 108 ELD-M at 2605 FPS with a relatively conservative charge (28.3 grains) of CFE223. That works for me but only just, and, as such, I am not inclined to reduce barrel length at this time.

    I'd rather have the longer barrel and extra weight than having to load maximum charges to achieve the objective. That's just my preference at this time. When factory brass is plentiful and I don't have to make it out of 6.5 Grendel brass, I might feel differently about that.

    Henryrifle
     
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    Bantam1

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    @Henryrifle I appreciate you shared knowledge. I'm going to load also and am not trying to load too hot either. I know Hornady is not using off the shelf powder for their factory loads. I'll probably be using CFE as well since it seems most are getting the best results with it. From what I have found and been told factory Hornady 108 ELD is running about 2630 in the 18" Proof barrel. I'm sure it can vary by barrel and ammo lot.

    I'm in CA so I can't have a suppressor or a short barrel. If I was going to run a suppressor I would go 18" without thinking about it. I'm trying to keep the weight down as much as possible but still have an accurate platform. The sub 2 pound carbon barrel makes a lot of sense to shave weight. My bolt guns and my 18" AR are heavy. If I can keep the weight to around the 18" AR (10 pounds empty) or less I will be happy.
     
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