What cans are we using on SBRs and AR pistols?

[Clint]

Will,

What loads besides the SOST have the most promising terminal performance from the 7.5" barrel?

Are there gel tests available that demonstrate terminal performance "vastly exceeding" or even matching common Duty Pistol, PCC and PDW loads?

What other PDW loads are you comparing to besides 5.7x28?

If the rec is defeating BA, limits choices. If not, a wide range of choices from all major manufacturers exist now that will do 2200-2400+ fps (depending on weight) and offer excellent terminal ballistics exceeding that of any pistol in typical duty loads, pistol caliber carbine, or PDW, by a margin, in SD/HD distances and then some.

I tend to view it a PDW that's using a rifle bullet, and an effective one at that, some can't let go of the rifle aspect, and continue to compare to rifle. Compared to a 10" you are giving up something to be sure, not nearly as much as some seem think for the role of HD/SD/PDW by the easy to supply numbers.

For example, the Federal MK 318 Mod 0 (SOST) 62g is barrier blind design, does 2200 fps from a 7.5 inch barrel and performed very well in jello testing by wide margin to any pistol in typical duty loads, pistol caliber carbine, or PDW. While that's not the easiest load to find, again, major manufacturers offer various similar. Anyone claiming "just use a pistol caliber carbine" at this point has no credibility here.

There is an argument to be made for longer barrel ARs to be sure, but it's also an apples to oranges thing to me. Conclusion:

7.5" (or dare I even say, shorter!?), is vastly superior to any any pistol in typical duty loads, pistol caliber carbine, or PDW.

It is inferior to longer barrels depending on the role it's intended for, but not as inferior as some seem to believe.

300BLK would be more optimal all around, but 5.56 is much less $ to run (and that's no small thing these days!), far more available, and more then adequate terminal ballistics with the right loads, which are now common. No, it's not the most efficient use the 5.56

Indeed, and a vid posted here where 7.5 barrel AR went through BA like nothing, and still resulted in good penetration. That too, ignored here. Even minus any hydrostatic wounding mechanisms, the 5.56 7.5" with proper loads at any SD/HD distances then some, is far superior to any pistol, any pistol carbine and any PDW I'm aware of, and anyone at this juncture who legit can't "get" that at this point, needs to go back and research the topic vs telling what a bad idea it is to use it for that use. That one can put it in a basic backpack, etc, is an obvious advantage to other options.

[WillBrink]

Will,

What loads besides the SOST have the most promising terminal performance from the 7.5" barrel?

Are there gel tests available that demonstrate terminal performance "vastly exceeding" or even matching common Duty Pistol, PCC and PDW loads?

What other PDW loads are you comparing to besides 5.7x28?

I listed some brands here in the thread already, all major brands offer rnds that perform well out of 7.5. I'm not aware of any 5.7 or common Duty Pistol, PCC that will out perform better than a 5.56 doing 2400fps + if you simply do the math there and apples/apples. There's a fair amount of vids out there doing gel test, not aware of any formal testing by SME's such as DocGR etc.

[Wake27]

I listed some brands here in the thread already, all major brands offer rnds that perform well out of 7.5. I'm not aware of any 5.7 or common Duty Pistol, PCC that will out perform better than a 5.56 doing 2400fps + if you simply do the math there and apples/apples. There's a fair amount of vids out there doing gel test, not aware of any formal testing by SME's such as DocGR etc.

Have you actually chrono’d any of this? I’ve paid attention to almost zero discussions on FPS until basically right now, but my 14.5 is pushing rounds slower than I would’ve guessed before testing myself. May be entirely due to altitude but definitely one of those things worth checking for yourself.


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[WillBrink]

Have you actually chrono’d any of this? I’ve paid attention to almost zero discussions on FPS until basically right now, but my 14.5 is pushing rounds slower than I would’ve guessed before testing myself. May be entirely due to altitude but definitely one of those things worth checking for yourself.


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Personally no, but I know people that have and video taped for me, and I posted several vids in this thread. Can altitude make that big of a difference? Those numbers are for 55g, 62 and above obvious slower, all well above the minimum velocities required for expansion and penetration.

This guy tested quite a few rnds from 7.5 barrel. Can't vouch for the methodology but there's lots of chrono etc info at least:

[grizzman]

Since I already had QuickLOAD open, I ran some calculations with Sierra 65 grain GameKings. I wasn't able to exceed 2300 fps with H322, Varget, 8208 XBR, 3031, or 2230. Most topped out between 2250 and 2275, at maximum 5.56 pressure.

[georgeib]

Well, Will, it seems you might have gone too long on your barrel after all... SOCOM is going with Sig Rattlers in 300 Blackout and 5.56 with 5.5" barrels, for PDWs.

https://www.sandboxx.us/blog/socom-p...efense-weapon/

[Outlander Systems]

The RSAR is a .300 and the 5.56 requirement is for a secondary/backup conversion kit.

Well, Will, it seems you might have gone too long on your barrel after all... SOCOM is going with Sig Rattlers in 300 Blackout and 5.56 with 5.5" barrels, for PDWs.

https://www.sandboxx.us/blog/socom-p...efense-weapon/

[georgeib]

The RSAR is a .300 and the 5.56 requirement is for a secondary/backup conversion kit.

Nope, I don't believe it. No one needs more than five inches.

[Outlander Systems]

That’s what she said.

[WillBrink]

Well, Will, it seems you might have gone too long on your barrel after all... SOCOM is going with Sig Rattlers in 300 Blackout and 5.56 with 5.5" barrels, for PDWs.

https://www.sandboxx.us/blog/socom-p...efense-weapon/

Short barrel AR/AR style guns are a thing (even 5"...) , a thing that will stay because they have a role to play, even in 5.56. The author posits some of the potential downsides of that too, but I suspect SOCOM well aware of the negatives, and concluded the juice well worth the squeeze and could have supplied the meat eaters with anything they'd want to.