brant89
Well-Known Member
What kind of velocities are you seeing in the 70-77gr bullets?
Shorty .223AI Velocity
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brant89
Well-Known Member
It seems to me that building a short barrel rifle in a speedier cartridge might be a little counterproductive when it comes to velocity preform, kinda like having a thoroughbred racehorse in the race then putting a 300 Lbs jockey on him with a roping saddle. It would seem as the barrels started coming down in length perhaps the original cartridge, in this case, .223 Rem would work just fine especially when going under 16" inch barrel length. But... if you just like the looks of the horse and the jockey is your brother-in-law why not?
Actually if you read my post, the idea is to get 26" 223 performance out of a shorter 223ai. I guarantee if you cut a 223 down from 26" and it's still a 223 it will absolutely not hit the same velocity. It's not like I'm trying to hit 3200fps with 80gr pills out of a 16" barrel. To be more precise about what I'm asking for; at what barrel length can a 223AI reliably push a 75gr ELD north of 2800fps.
Well, I do understand what you're asking, I was just trying to parallel cartridge relationship with shorter barrels even with a larger capacity case, perhaps a bad example on my part. So, unless there is a .223 AI shooter that worked the ballistical solution you've asked about'..., it's pretty much a crapshoot.
Perhaps comparing with something that might be as close, but... I know not the same would help.
Black Hills 77 gr TMK Muzzle Velocity:
14.5 inch barrel: 2589.4 FPS avg.
(Daniel Defense and BCM lightweight hammer forged chrome lined, carbine & mid-length gas system)
16 inch barrel: 2683.1 FPS avg.
(BCM C8 SFW heavy profile chrome lined barrel w/ Simon steel sleeve, carbine-length gas system)
18 inch barrel: 2687.5 FPS avg.
(Rainier Arms Select Medcon stainless polygonal rifling, mid-length gas system)
18 inch barrel: 2712.5 FPS avg.
(BCM Mk12 SPR heavy profile stainless steel, rifle-length gas system):
Now, thinking about your question; perhaps 18" inch barrel might be the magic sweet spot for your project. Good luck.
brant89
Well-Known Member
I've been looking up some of these 77gr loads as well for a comparison, but 5.56 isn't 223 so I doubt I'll get the quoted 150-200fps gain over the higher pressure round. However it does look like 20 should definitely get me into the 2800's and 18" might. I also found an article where they cut the barrel on a 5.56 and lost about 100fps going from 22" to 18" (they started at 26"). That would suggest (based off J E Customs 22") that I could get as high as 2900fps out of an 18". I think you hit the nail on the head with it being a crap shoot. I guess I'll just try it and see what happens.
Ernie
SPONSOR
H-S Precision HSP 223 Rem Copper Creek 77 grain Berger OTM (15") MV 2500 fps
Rear-grip XP-100: 15" 223 with 73 grain Hornady ELD-M ammo 2626 fps/75 grain BTHP 2673 fps
Different rear-grip XP-100R: 15.5" 223 Rem with the 73 grain ELD-M ammo is 2535 fps
B23
Well-Known Member
Also as a side note, keep in mind, when you get down around the 18in barrel length, even suppressed, they are considerably louder. Not exactly apples to apples comparison, but I had my 22-250 chopped down to 18in and even shooting it suppressed, it's to loud to shoot without hearing protection where as my 223AI with its 22in tube is still very quiet shooting it suppressed.
brant89
Well-Known Member
brandt89,
Yeah, it's kind of a toughie with the .223 AI I looked through three of the P.O Ackley reloading manuals that he wrote, P.O wasn't real happy with or about the .223/5.56mm cartridge from what I can see in his comments he never really did much if anything with the .223 Rem, in retrospect that's kinda odd'.., because he did quite a bit with the .222 Rem AI and the .222 Rem Mag AI... I thought perhaps I could dig something up that you could use'.., no joy. I'm still thinking an 18" inch perhaps something like; Pac Nor's polygonal 1-9 twist l like this twist rate for bullets up to 77grs but there is always the 1-8 twist, I've used both and the 1-9 twist seems to Chrono little higher in my .223's rifles. Just a thought.
Yeah, it's kind of a toughie with the .223 AI I looked through three of the P.O Ackley reloading manuals that he wrote, P.O wasn't real happy with or about the .223/5.56mm cartridge from what I can see in his comments he never really did much if anything with the .223 Rem, in retrospect that's kinda odd'.., because he did quite a bit with the .222 Rem AI and the .222 Rem Mag AI... I thought perhaps I could dig something up that you could use'.., no joy. I'm still thinking an 18" inch perhaps something like; Pac Nor's polygonal 1-9 twist l like this twist rate for bullets up to 77grs but there is always the 1-8 twist, I've used both and the 1-9 twist seems to Chrono little higher in my .223's rifles. Just a thought.
flyinstroke
Well-Known Member
I am looking into a 20" with 5R rifling from X-Caliber. Hoping to shoot the heavies. Will be used mostly as a plinker but i am hoping to get at least 2800 fps out of her
