Experienced feedback on 10.5 ar barrels

[Ghillie Zen]

I'm looking to build an AR upper with a 10.5 barrel dedicated to maximizing 55gr accuracy and consistency.

I currently have a LMT 10.5 1:7 that shoots 55gr pretty good (1.5-2 moa 100yds), but performs better with heavier rounds.

I'd like to try out a 10.5 with a 1:9 twist to see if I can tighten up my groups a bit. The barrel I'm considering is the YHM 10.5 fluted w/ 1:9 twist.

If anyone has hands on experience with the YHM or any 10.5 with 1:9 while using 55gr, I'd appreciate your input. Please remember that I'm dedicating this specifically to 55gr when responding. Thanks.

 

[KevinB-KAC]

Re: Experienced feedback on 10.5 ar barrels

55gr ammo is not exactly match.

If your looking to tighten up the groups with lighter weight ammo, then a match lighter round will be a better option.

Try a 52gr OTM load if you reload.


A 1:7 barrel is not (despite repeated internet hyperbole) not going to be less accurate with a 55gr bullet than a 1:8 or 1:9 twist, and the quality of the barrel will be a bigger determiner than the twist rate of those.

 

[krg648]

Re: Experienced feedback on 10.5 ar barrels

My PD saves brass and we use the money from it to put back into our firearms program. I have since built myself a great duty rifle. Noveske lower, Geissele SSA trigger, Vltor IMOD stock, Larue 11" gooseneck rail, 10.5" Noveske barrel, Surefire FS topped off with Troy flip up irons. From the 100yr line using 55gr american eagle (because the pd has mass amounts of it) I get a consistant .5"-1" group all day. Now I know I have a top quality barrel but the trigger is also in my mind perfect. Some slack then a nice crisp break. To get good groups outta a short barrel using 55gr you will need a good barrel and trigger combo.

 

[Ghillie Zen]

Re: Experienced feedback on 10.5 ar barrels

Agreed Kevin, 55gr is not optimal, but since I'm not handloading, the 55s are what is most affordable and commercially available to me. I'm aware of the limitations of the 55 and the inherant issues with factory load consistency. The point of this specific build is to create an upper that will simply make the most of what I have to work with.

Based on your last statement, are saying there would be no discernable difference between the 100, 200, 300yd groups of two identical barrels (one in 1:7 and the other 1:9) using brand x 55gr? Would the twists results be different in regards to opening up at greater distances? I'm not questioning your knowledge, just trying to make the most informed decision possible.

 

[Ghillie Zen]

Re: Experienced feedback on 10.5 ar barrels

Good point as well KRG... I actually have a Geissele SD-E on the way! It will definately help refine my groups compared to the shit trigger thats currenty sitting on the lower I'll be using.

 

[krg648]

Re: Experienced feedback on 10.5 ar barrels

Let me know hw you like the SD-E, I love my SSA trigger. I just bought another SSA for my SPR personal build i'm starting.

 

[Frank]

Re: Experienced feedback on 10.5 ar barrels

My experience with fast twist barrels is that they will shoot light weight quality bullets ie:52/53 match, V-max, Nosler Ballistic tips etc very well. The problem shows up with lower qualty bullets, the extra spin seems to magnify any imperfections in balance and opens up the group with lots of flyers. I try to keep my twist as slow as possible for the application/bullet weight I need. I've also seem a 1-7 twist smoke hot loaded 55 grainers about 1 in every 7-10 rounds until the barrel had over 1K rounds thru it.

 

[KevinB-KAC]

Re: Experienced feedback on 10.5 ar barrels

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Ghillie Zen</div><div class="ubbcode-body">Agreed Kevin, 55gr is not optimal, but since I'm not handloading, the 55s are what is most affordable and commercially available to me. I'm aware of the limitations of the 55 and the inherant issues with factory load consistency. The point of this specific build is to create an upper that will simply make the most of what I have to work with.

Based on your last statement, are saying there would be no discernable difference between the 100, 200, 300yd groups of two identical barrels (one in 1:7 and the other 1:9) using brand x 55gr? Would the twists results be different in regards to opening up at greater distances? I'm not questioning your knowledge, just trying to make the most informed decision possible. </div></div>

No such thing as an identical barrel

Everyone has a different take on barrel twist -- frankly if you don't have a dopler and access to a large number of barrels in each twist and record the data there is no way to make a true determination.

In my experience I have seen the 1:7 twist to do better, I only had 3 of each barrel when I was playing with this in the 2003-4 time frame, and the barrels where not all identical (1:7's where a Armalite, Douglas and Colt Canada, the 1:9's where an Armalite, Bushmaster and Colt) - the Douglas SS barrel killed the others, followed by the Colt Canada, and then the Colt.
I remember enough from College Stats that it really was not a statistically valid sample size.


However if your going to build a new upper - it may be worth just keeping your current gun, and investing in reloading gear so you can tailor loads to your gun...

 

[BCP]

Re: Experienced feedback on 10.5 ar barrels

Investing in another barrel might help a bit but without high quality ammunition you are rolling the dice for accuracy. Also what's wrong with 2" groups from a 10.5" barreled SBR?

 

[Sterling Shooter]

Re: Experienced feedback on 10.5 ar barrels

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: KevinB-KAC</div><div class="ubbcode-body">55gr ammo is not exactly match.

If your looking to tighten up the groups with lighter weight ammo, then a match lighter round will be a better option.

Try a 52gr OTM load if you reload.


A 1:7 barrel is not (despite repeated internet hyperbole) not going to be less accurate with a 55gr bullet than a 1:8 or 1:9 twist, and the quality of the barrel will be a bigger determiner than the twist rate of those.</div></div>

+1, my match conditioned commercial equivalent of the M16A2, which is fitted with a 20 inch SS Douglas 1/7 smithed by Frank White is used primarily these days for NRA LR Service Rifle division events where I shoot an 80 grain Berger; however, for 100 yard reduced course events, I shoot the flat base 53 grain Sierra. With this bullet and irons, 20 round for record strings produce groups as small as I've ever produced using slower twist match barrels.

 

[Ghillie Zen]

Re: Experienced feedback on 10.5 ar barrels

Thanks for the input guys!

Kevin - That's the type of comparisons I was hoping to find. When you conducted those tests, do you remember what the round specs were that you used?

Frank - You hit on part of what I was thinking when I originally posted. My thought was the same as yours when using lesser grade ammo. The idea being to keep the spin slower to help keep the inconsistencies more under control.

BCP - Nothing wrong with 2 moa if it's cheaper ammo, but I believe higher quality factory loads (Hornady, Black Hills, Fiochii, etc..) should do be doing better if I do my part.

I don't mean to complain about the performance I'm currently getting out of the LMT barrel, it's awesome with heavier rounds. I don't handload 223/556, so this is more about fine tuning my rig to make the most out of what is locally available in bulk and unfortunately, stores that sell AR ammo in my general area tend to only have 55gr.

I'm going to install the Geissele SD-E, put a higher power optic on it and give her some love at the range this weekend. I was originally using a Vortex PST 1-4 when shooting for groups at 100, so with the addition of the trigger and a Leupold Mark AR 3-9, I may be able to dial things in enough that the barrel will become a non-issue; hopefully...

 

[KevinB-KAC]

Re: Experienced feedback on 10.5 ar barrels

It was older M193 - that literally was years ago, and many different jobs in the past. Most of the stuff was done with 77gr HSM and C77 (Canadian SS109) 62.9gr ball.

The issue your facing is the projectile - not the quality of the load. 55gr FMJ was never designed as match ammo, and the tolerances on the projectile are relatively loose. You may find a lot of bullets that does quite well - and another that is 3MOA.

I don't think you will find any barrel that will reliably shoot 55gr FMJ at the your desired accuracy level.

 

[Oddball Six]

Re: Experienced feedback on 10.5 ar barrels

http://www.southwestammunition.com/category_s/59.htm

Difficult to justify not using match rounds if you are looking for groups rather than run/gun practice ammo.

 

[Ghillie Zen]

Re: Experienced feedback on 10.5 ar barrels

Great link Oddball-Six! Thanks for making my wallet a lil lighter