24" AR Barrel - Need Help/Info

[blboyd]

I've built quite a few AR's over the last couple years but recently I put together a precision rifle. The barrel is a Wilson AirGauge 24" 1in8" fluted bull barrel and I can't get it better than 1-1.25" at 100yds.

I'm using match prepped brass and running various loads of VARGET pushing 77gr Sierra MK's and 75gr Hornday Match. Even using factory loaded match ammo I'm still not better than 1". I think I have reached the best the barrel will do. I was hoping for 3/4" or even 1/2" at 100yds.

I don't think it's my driving either because I can swap out and drive my 700PSS .308 and punch consistent 1/2" groups.

So I say all of this because I'll be looking for a better barrel within the next couple months.

Does anyone make a 24 or 26" bull barrel with a match chamber? Shilen, Krieger, etc? Maybe even one that is designed to sling 77gr Sierra's seated to mag length?

Thanks!
Whisper

 

[ltfirehunter]

Re: 24" AR Barrel - Need Help/Info

I have noticed on some of my 1n8r's and 1n9's that they just plain don't like the 77's.

The 69's have alwaays seemd to be the pick.

My older service match finally come to life with the 77 and 80 gr. bullets once I went to the 1n7.25 Kreiger barrel

 

[GasLight]

Re: 24" AR Barrel - Need Help/Info

because you can shoot a 1/2" group at 100 with one gun, doesn't mean that automatically translates to other rifles. ARs drive different than bolt guns. What trigger and pull weight is in your AR? how is your follow-through? There are a lot of factors...

Dave

 

[blboyd]

Re: 24" AR Barrel - Need Help/Info

The trigger is a 2-stage 2lb pull. It started life as a standard single-stage 8lb GI trigger but I worked it over.

I feel that my follow-through is good. I'm by no means an expert shooter but I can watch the hit through the glass.

I might try to pick up a box of 69's just to see if it likes them.

 

[ltfirehunter]

Re: 24" AR Barrel - Need Help/Info

I'll send ya a few 69's if you would like.

 

[Bronco]

Re: 24" AR Barrel - Need Help/Info

Before you give up on this barrel try some 80 gr. SMK's. I've got a no name 24" 1 in 8 that shoots 80's into .75, 77's hover right around 1". At distance the 80's are even better. Able to push them in the 2850 area easy. Did add a weight to the bolt group and used RL-15.

 

[blboyd]

Re: 24" AR Barrel - Need Help/Info

ltfirehunter - PM Inbound

I wanted to try 80gr Sierra's but you can't seat them to mag length right?

I'm using a standard A2 buttstock with the rifle-length spring and buffer but I cracked open the buffer and added another weight.

 

[ltfirehunter]

Re: 24" AR Barrel - Need Help/Info

No, the 80's I run would have to to be single feed.
I got my follower from Sinclair international.

They are a little long for the mag.

The 80's will need a faster twist, along the lines of a 1n7.
A 1n8 twist will work but it seems to be a little more finicky.

 

[Bronco]

Re: 24" AR Barrel - Need Help/Info

The 80"s are long, need to measure where the lands start in your barrel and seat them .005 to .010 off lands. A lot of guys chase the lands as the throat erodes. Mine is around 2.485 as I recall, but measure to be sure.

 

[ltfirehunter]

Re: 24" AR Barrel - Need Help/Info

Yeah, after ya run em out there to get close to the lands they start lookin like a short pencil.

But they do buck the wind nicely.

 

[blboyd]

Re: 24" AR Barrel - Need Help/Info

I was really hoping this would be a mag-fed rifle. I'll give these 69's a try and see where I end up.

I might even try some 80's single fed and see if the groups shrink.

So far no matter what kind of match ammo I run it won't drop under 1".

Thanks for your help guys!

 

[cyberpuppy42]

Re: 24" AR Barrel - Need Help/Info

It may not be just the barrel, With an AR, other factors come into play as well just because there's a bunch of moving parts involved. My .223 AR (OlyArms PCR-1, 24" bbl 1:7) can print .2 groups at 100 yards with 80s, but I had to do quite a bit of load development to get there. That's with hand-feeding the rounds individually because they're too long for the mag. I think even with factory 62s and 69s it was doing sub-MOA, but it's been a while since I did that testing so I don't remember for sure.

 

[ltfirehunter]

Re: 24" AR Barrel - Need Help/Info

Once you hit the sweet spot with an 80gr. bullet they are great.You will almost wanna crack the gun accross your own head.

 

[Sterling Shooter]

Re: 24" AR Barrel - Need Help/Info

First, chronograph the ammo. It would appear to me, you're getting inconsistent pressure/velocity from, perhaps, inconsistent primers, or cases. Weigh your cases, make sure neck tension is consistent, and de-burr the flash holes. The idea is to get more consistent velocity, as well as consistent recoil.

Remember, the 77 grain bullet is heavy enough to make recoil control (follow-through), from trigger pull to bullet exit, very important. Velocity/pressure divergence between rounds, of course, effects recoil-it becomes inconsistent; and, even with consistent contact with the rifle, you're precluded from getting really small groups, as the muzzle will be at a different place with each bullet's exit.

Your problem is not with the bullet, twist, bullet stability, or brand of barrel. Think about it. Chronographing will reveal the inconsistent pressure/velocity. Although low SD and ES is not particularly meaningful at 100 yards, it will become very meaningful as the target distance increases, as both the recoil divergence and velocity divergence will defeat any attempt to get a really well defined zero, too much angularity. Get the load right, and, hang on to gun until recoil subsides; and, you'll see sub moa performance.

Once again, it's about recoil. No wonder folks get better results with the 69 grain bullet, it has less recoil. I can shoot it better than the 77; but, I cannot shoot it as far with desired results. That's because the 77 has a a higher BC than the 69. If, BC was not important, I'd be shooting a 53 grain match bullet at LR, as it, with very low recoil, does not require the sort of control from trigger pull to bullet exit, as do the heavier bullets.

 

[blboyd]

Re: 24" AR Barrel - Need Help/Info

Here's what my load looks like through my load development process.

Load:
<div class="ubbcode-block"><div class="ubbcode-header">Code:</div><div class="ubbcode-body ubbcode-pre" ><pre>
Cases: R-P Match-Prepped
Uniform Primer Pocket
Debur Flash Hole
Trim length
Chamfer case mouth)

Bullet: 77gr Sierra HPBT Matchking
Seated to mag length(2.260)

Primers: Federal Gold Metal Match
</pre></div></div>

Here's my chrono data:

Powder: Hodgdon VARGET
<div class="ubbcode-block"><div class="ubbcode-header">Code:</div><div class="ubbcode-body ubbcode-pre" ><pre>
Weight AVG ES Actual SD
24.4 2826 41 129
24.6 2787 38 146
24.8 2798 21 78
25.0 2796 11 26
</pre></div></div>

I've settled on the 25.0gr of VARGET load. I have no signs of pressure at 25grs.

Thanks,
Whisper

 

[lostriverproductions]

Re: 24" AR Barrel - Need Help/Info

I would give 69 grainers a try. Most factory barrels should hold 1" Mine is a 20" 1-9 twist and is a tack driver

 

[Sterling Shooter]

Re: 24" AR Barrel - Need Help/Info

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Whisper</div><div class="ubbcode-body">Here's what my load looks like through my load development process.

Load:
<div class="ubbcode-block"><div class="ubbcode-header">Code:</div><div class="ubbcode-body ubbcode-pre" ><pre>
Cases: R-P Match-Prepped
Uniform Primer Pocket
Debur Flash Hole
Trim length
Chamfer case mouth)

Bullet: 77gr Sierra HPBT Matchking
Seated to mag length(2.260)

Primers: Federal Gold Metal Match
</pre></div></div>

Here's my chrono data:

Powder: Hodgdon VARGET
<div class="ubbcode-block"><div class="ubbcode-header">Code:</div><div class="ubbcode-body ubbcode-pre" ><pre>
Weight AVG ES Actual SD
24.4 2826 41 129
24.6 2787 38 146
24.8 2798 21 78
25.0 2796 11 26
</pre></div></div>

I've settled on the 25.0gr of VARGET load. I have no signs of pressure at 25grs.

Thanks,
Whisper</div></div>

O.K., here's what I'd do-try Winchester primers. Expect SD in the 7 to 8 range. BTW, my 77 grain load is over 24.1 grains of RE-15 in massaged Win. brass primed with WSR primers. From my current CLE chambered 20 inch Service Rifle barrel, I'm getting about 2750 fps with single digit SD.

Nevertheless, I think your current loading should get em all right in there. The 77 grain load has enough recoil however that you will need to perfect NPA and follow through. In other words, I think your 77 grain load is revealing you need some work on perfecting your position.

 

[RH4540]

Re: 24" AR Barrel - Need Help/Info

Even though when I had my 1-8 twist barrel, I never tried 77 grain bullets, I did try Sierra 69s and Hornady, 68 grain match hollow points. It hated the Sierras, but, produced tiny, little groups with the Hornady 68s pushed with 25 grains of Varget. After putting over 10,000 round of that load through it at prairie dogs, the barrel was shot out.

 

[Sterling Shooter]

Re: 24" AR Barrel - Need Help/Info

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: RH4540</div><div class="ubbcode-body">Even though when I had my 1-8 twist barrel, I never tried 77 grain bullets, I did try Sierra 69s and Hornady, 68 grain match hollow points. It hated the Sierras, but, produced tiny, little groups with the Hornady 68s pushed with 25 grains of Varget. After putting over 10,000 round of that load through it at prairie dogs, the barrel was shot out.</div></div>

I'd guess your barrel was actually gone at somewhere around 3000 rounds. 15 barrels in the last 6 years or so has suggested to me somewhere at around 3000 rounds, in HP, X counts begin drop from average on the 600 yard target.

 

[trilogymac]

Re: 24" AR Barrel - Need Help/Info

Well Mr. Whisper, I think you found your load at the range today.
Nice meeting you. PM me when your going again.

Best,

Trilogymac

 

[blboyd]

Re: 24" AR Barrel - Need Help/Info

Hey Trilogymac - Nice to meet you! Very impressive weaponry you carry along.

Well fellas - Today was an interesting day at the range.

I've been fighting this rifle for 3months and never could get under an inch. I've been running 77gr Sierra's with no luck so I switched to 69gr Sierra's.

Here's some quick preliminary data:

<div class="ubbcode-block"><div class="ubbcode-header">Code:</div><div class="ubbcode-body ubbcode-pre" ><pre>
R-P Matchprepped Cases
Federal GoldMetal Primers
69gr Sierra HPBT

Hodgdon VARGET
25.5gr .40" 5shot group
25.8gr .45" 5shot group
26.0gr .52" 5shot group
</pre></div></div>

I don't have any chrony data yet. I'm hoping to get some trigger time in when I visit my folks over 4th of July.

Whisper