AR Platform for F/TR - barrel length?

[jelenko]

This will be my 5th upper from WOA over the years. Always been happy before.

 

[Park ranger]

I’d go with 22”.

 

[AR Shooter]

You need to read the AR tactical class rules. The NRA swears it’s not but it’s basically F-AR and last time I looked it was still shot on the “big target”

I much prefer big targets. ;-)

 

[VA_XTC_Shooter]

Holliger (WOA) is building the upper with a side charging handle. This will be my 5th upper from WOA over the years. Always been happy before.

Holliger sold WOA

 

[jelenko]

I’d go with 22”.

Why?

 

[Stumpy1]

Probably because by CMP Rules, 22 inches is the maximum barrel length.
Rumor has it that the NRA is likely going to the same barrel length limit.
(all for AR-Tactical Class)

Frank

 

[jelenko]

Probably because by CMP Rules, 22 inches is the maximum barrel length.
Rumor has it that the NRA is likely going to the same barrel length limit.
(all for AR-Tactical Class)

Frank

Ah.
If for FTR, you'd be giving up ~ 100 fps.

 

[Park ranger]

Guy (vendor) at Camp Perry told be that NRA has accepted the 22” rule now. I don’t know, I only really shoot CMP matches. So a 22” AR15 in 223 would be awesome for a one upper situation, properly twisted of course.

F/TR legal for 600. Yes, you lose 100 fps, and probably the accuracy needed to win. But, that game will make you focus and humble.

Then you could use it for 1000 yard AR-Tac with a 85.x grain Berger. Get it to 2800 fps. Brass is cheap. That’s basically a 308 with juggernaut in a M110 but a lot less recoil and I think a AR 15 platform is easier than an AR10.

Me, I like my 6 ARC in a 22” AR.

 

[Jon Leary]

Holliger sold WOA

I shot a 396 at 600 in AR tactical with a white oak 20 inch 7 twist barrel.

 

[AR Shooter]

Ah.
If for FTR, you'd be giving up ~ 100 fps.

Now that I've become familiar with the AR-Tac rules I'm going with the 22" barrel. The rules suit me well.
Will shoot F/TR with my bolt gun.

 

[AR Shooter]

I shot a 396 at 600 in AR tactical with a white oak 20 inch 7 twist barrel.

I'm guessing that was a 40-shot match?
Mind sharing your load info?

 

[Laurie]

Hmmm......... will the Berger 85.5 work in an 8" twist?

No.

Select it from the bullet menu in Berger's online twist calculator, and 8-twist is plainly inadequate at most altitudes and temperatures. It becomes a marginal case in high temperatures and at very high altitudes. If you only shoot at Raton, ca. 6,559 ft ASL, on hot summers days, you're fine!

https://bergerbullets.com/twist-rate-calculator

(Even the 80.5gn BT and other 80s are marginal in many conditions in 8-twist according to the Litz / Berger criterion of Sg=1.5 or higher, although Berger said 8 was suitable when it introduced the bullet. I don't reckon that's anything to worry about given actual Sg values above 1.4.)

 

[Heman]

No.

Select it from the bullet menu in Berger's online twist calculator, and 8-twist is plainly inadequate at most altitudes and temperatures. It becomes a marginal case in high temperatures and at very high altitudes. If you only shoot at Raton, ca. 6,559 ft ASL, on hot summers days, you're fine!

https://bergerbullets.com/twist-rate-calculator

(Even the 80.5gn BT and other 80s are marginal in many conditions in 8-twist according to the Litz / Berger criterion of Sg=1.5 or higher, although Berger said 8 was suitable when it introduced the bullet. I don't reckon that's anything to worry about given actual Sg values above 1.4.)

What Laurie said is correct, BUT I will say there are a lot of SR shooters that shoot 8 twists and shoot 80s of various flavors at 600 and shoot just fine. I had a 24" RRA Varmint upper that shot 80s just fine and it was a 1:8 twist. Only reason that barrel didn't get used as a match barrel was it had several prarie dog hunting trips on it and got hot.

 

[Jon Leary]

I'm guessing that was a 40-shot match?
Mind sharing your load info. Yes it was a forty shot match. Conditions were ideal. I was clean on the 2nd string but leaked an 8 on the final shot. 80 gr SMK and varget.

 

[AR Shooter]

JonL - thx for the info. I've never had a problem shooting 80gr SMKs or Bergers in my 8" twist barrels with 24.5gr of Varget.

 

[Jon Leary]

JonL - thx for the info. I've never had a problem shooting 80gr SMKs or Bergers in my 8" twist barrels with 24.5gr of Varget.

My load is 25.4. White oak barrel. I think they are a wylde chamber

 

[323]

My load is 25.4. White oak barrel. I think they are a wylde chamber

Would definitely work up to that.

 

[323]

I would buy a bison Armor 1-6.5 twist barrel run 85.5 bergers with n540 and don’t look back. I’m avg 2780 out mine and they shoot phenomenal will hold 10 ring at 600 all day long that’s slung up (SR) and if I do things right.

 

[Jon Leary]

Would definitely work up to that.

I tried 25 gr and it looked ok so I tried 25.4. It worked great and SD of 5. Had 21 x,s.

 

[sfinn1]

Fellas, before giving advise for an AR Tactical rig, I would recommend that the rules concerning the length of loaded ammo be known. Another words does it need to be magazine loadable?I have tried to get that information from the NRA with no success. CMP I don't know. Shooters I'm around and have shot a large matches tell me it's mag length only. The heavier bullets won't fit that bill.
I'm not trying to start a lengthy discussion to divert from the original post. But that needs to be addressed.