Accurizing a Grendel - Accuracy Advice

[Eye_guy]

[BlogSarge]

[Eye_guy]

[biodsl]

I was shooting 1/3-1/2 MOA the same day with my AR-10...

Curious and related to the topic at hand: who's barrel is in your .5 MOA AR-10?

[Eye_guy]

Curious and related to the topic at hand: who's barrel is in your .5 MOA AR-10?

[biodsl]

Well, you won't find me knocking them. Twenty years ago they were building sub minute 5.56s

You probably don't want to hear this, but I'd recommend you save yourself time, money and frustration and ditch the barrel. Perhaps you could try to utilize the BA guarantee. Perhaps the next one would get you where you want to be. Or upgrade to a premium barrel. Which ever you do, don't waste anymore time on the barrel you have. Obviously you can shoot. That BA barrel can't.

[Klem]

Eye,

Save up your pennies and spend an extra $200 on a decent barrel. Then you can focus on bringing the rest of the gun up to the barrel's potential. Doing up screws and gluing joins is not going to make that barrel shoot better than its potential.

(Blog Sarge,) Those Zev billets are formerly Mega Arms - good advice, they are very well respected and pleased to see them finally offering the original Mega design again - 7075 T6 aluminum, ambidextrous slide locking release.

[grendelnubi]

I believe what you have to do is find the right combination for that barrel. Sometimes it takes a lot of time, patience and resources to find what it likes.

I just finished burning thru over a 120 Speer 120gr Gold Dots trying to find the right combination. I thought it was never going to happen but ended up finding two loads that worked. Both shoot .5 MOA at 200 yards which exceeded my expectations.

I have used the 129 ABLR for several years now and did find a pet load for the 129 ABLR using AR Comp. No other powders I tried worked and they did include 8208 and CFE223. AR Comp, however was the key to making it work.

Your grouping is not that bad. What gets me worked up are flyers and your group is pretty clean. Curious what your extreme spread and standard deviation was for this load.

You may want to start looking at seating depth to see if you can tighten up the group. What worked for me was a COAL of 2.265 with OTB of 1.644. That is a 147 thousands jump, which for me, I thought that is a lot of jump but it worked. Keep working on it.

[mtnlvr]

Other things to consider. Try the scope from your AR10 to rule out any issues with your existing scope / mount. Is there anything within the handguard that could be contacting the gas block or barrel during the shot? Does the barrel crown look appropriate...sufficient size, angle and concentric to the bore? It wouldn't hurt rebuilding the upper and taking those small steps of truing the receiver face, bedding the barrel, using a moly grease or appropriate anti-sieze on the extension threads and properly torquing the barrel nut. These are all things that you can do with no or little investment.

[Eye_guy]

[mdram]

i will say that i start my loads at max oal.
once i find a group, i start a seating depth test, .003 increments.
the group will change with various depths for the same bullet

[montana]

Purchase the best barrel you can afford, find the best bolt shoulder to bolt carrier fit you can find, then the trigger and optics.

[lazyengineer]

#1 - bullet. Personally, I'm not a nosler fan. Start with the TNT 90 (yes, the TNT90), it is insainly forgiving. The 107 SMK HPBT is an exceptional bullet as well. While Grendel was designed for 123 in mind, for whatever reason, I can never make a 123 sing that well.
#2 - Barrel. Really, the crown and chamber and trhoat are what matters the most. I've seen chatter uggly barrels turn into tack-drivers, with a good and proper uniform throat and a decent crown. I think Alexander Arm's makes a very accurate barrel. Others I'm sure are good too, but the basic PSA BBL is going to be a dice-roll. To be honest, I like Faxon as good value, but they too can be a dice roll at times. If you're frustated, spend the money and get a good barrel from the get-go. The more you spend, the less likely it will be a dice-roll gamble.
#3 - twist rate. I'm the only guy in teh room who doesn't like 1/8. Bill Alexander said hiimself he could not get a 1/8 to shoot well, and found that the 1/9 in a 20" was more inherently accurate. After going through a few barrels, I found the same thing. If you are going 16", 1/9 might be too slow, but since you want an accurate rifle, I'm assuming you want distance too, which means 20". And a 20" 1/9 will stabilized 129 gr bullets just fine. I like 1/9.
#4 - correct assembly (well, this is really #1 by far, but I'm putting it last, because you should have already done that, and this is more of a reminder). AR's are insainly forgiving, in my experience. You can have a barrel nut at 20 ft-lb, or 80, and it doesn't really matter. You actually don't need a top supreme scope mount or glass or trigger, but they do need to be tight and consistent. I run a $20 amazon mount, and just shot a 100-8x clean at 500 yards. and then a 200 clean at 600 yards. For glass, I run a PSA $500 scope (LOVE their 2.5-10x Griffen GLx). Beware with cheap scope mounts, the biggest issue is the cheap screws, that will stretch out. I really like the HIRAM mount, as they use good screws and steel inserts in the mount, for where the screw engages, It's quite strong. so yea, I actually like the HIRAM and UTG mounts, and think they are fine. Beware buying other cheapies that aren't one of those 2.


#4 trigger. If the gun doesn't go off exactly when you want it to, and doesn't stay on target when you told it to go off, it will never shoot well. For trigger, I run a Larue MBT. Geissle is better, but the Larue is good. All of these are cost-effective systems, but not junk. Also, almost all my triggers run 2-stage 4.5#. This is what I run in competition, and by being two stage, you stack the force, and so break with only an additional 2# on top of that 3# on teh first stage. Be very careful of some super awesome 2# total trigger. Aside from pulling an Alec Baldwin, In my experience a straight 2 or 3# trigger is so light, you aren't quite as in control of EXACTLy when that gun discharges, like you are with a 4.5# trigger that you're already stacked 3# on, and are tightening it up for that small but in-control incrememtnal increase break. single stage triggers have gotten a lot more populare of late, but sure as heck not with me - get a good 4.5lb 2 stage trigger.

Other items like lapped recievers, etc --- eh, I personally think those are overstated in importance, but who knows, maybe.


Current build:
-Anderson lower
-Larue 2-stage MBT
-PSA bolt carrier group and build kit (IMHO PSA makes excellent parts for a very good price point - but I will say the Horde bolt sold here, is a better bolt and extractor, and I have two more on order)
-PSA handguard and barrel nut. I personally am not a fan of the current over-lenght handguards, and always run my gas-blocks expossed for maintenance. So this one is a A2 length aluminum light weight handguard, that I quite love. that, and I never liked Manlnicher length stocks on wooden guns, and don't find the aesthetics of same that attractive on modern guns either.
-Alexander arms 20" HBR 1/9 with their goofy oversized diameter gas block and muzzle pitch thread and flash hider. 'Goofy', because they're somewhat non-standard. Good, because Bill Alexander ignores conventional wisdome, and optimizes on what he thinks best. If Bill Alexander says it should be this way, I listen.
-PA 2.5-10x GLx Griffen scope
-HIRAM 30 mm mount
-Cheap amazon graphit bipod (probably the one thing I should upgrade next, but it works), with quick release M-Lock mount included.
-basic Magpul CTR stock
-GI AR15 A2 pistol grip (IMHO, a greatly underappreciated pistol grip, it fits my hands perfectly)
-My preferred target load: 107 SMK HPBT over 8208 powder in Hornady brass.

One thing I learned about Grendel, - tape a spare extractor in your pistol grip. I've broken I think 3 by now. But never broke a bolt, FWIW.

[Eye_guy]

[lazyengineer]

In my experience you can pretty much run TNT 90's with charcoal, and still get 1 MOA. I also consider it a viable deer bullet, considering the huge number of very tough big hogs DNS downs out to 300 yards with one-shot-drops, constantly. I'd run that bullet on deer out to 200 yards without worry, personally. I dropped a >200 lb hog one-shot-drop with a TNT 90. If it can do that to a tough hog, it sure can drop a 150 lb thin-skinned deer.

In 7.62x39 brass, I run 26.5gr LT32. In regular Grendel brass, I have lots of good loads, and run 30.8 gr of CFE223, or 31 gr IMR8208 or 31 gr TAC. All of them shoot 1 MOA or better, even in barrels that I struggled with in general.