Beginning to think I got a pig for a barrel. I have had this Grendel for several years. Have never been happy with its accuracy. The amount of money I have in the upper I should be easily in the 3/4-1/2 inch range. Instead it typically throws an inch and a half group sometimes worse, sometimes better. The pic below is a typical group with Hornady factory 123 gr SST. I have tried 3 different powders and three different bullets and all combinations thereof. Upper specs are as follows: The barrel is a Satern 18 in heavy stainless cut rifled barrel, bolt is Satern that came with the barrel. Bolt Carrier is LMT enhanced. Upper receiver is a VLTOR MUR-1A. Charging handle is Radian Raptor. Handguard is VLTOR CASV-MT. Scope rings are Burris Extreme tactical. Scope is a Burris Fullfield II E1. Gas block is JP adjustable. Trigger is a reworked standard trigger that breaks cleanly at ~4 lbs.

Things I have tried:
1. Ensured gas tube was not impinging on BCG
2. Lapped receiver ring
3. Bedded barrel extension
4. Changed scope to a known good one
5. Swapped to a different lower (from my damn accurate .300 BLK)
6. Bought a bore scope to check the barrel and crown for imperfections. It's smooth as a baby's butt.
7. I even changed the nut behind the trigger to see if someone else could do better.

All to no avail. I have had a Midway AR-Stoner upper in my cart for a couple weeks with my finger hovering over the check-out button. A buddy has an AR-Stoner upper and it shoots dimes.

Any ideas?

Never mind about pics. Phone updated and cannot get upit to work.

I have nothing to add other than this sounds like an ongoing conversation I have with my golf clubs.

How's your rest? Good and stable? Trigger? Wind? Etc

Are you able to shoot a tighter group with a different gun in the same setup?

Is your buddy able to shoot your gun next to his and not able to do any better?

1.5" might be as good as it'll do.

Tried different ammo?

Pepper Brooks said:

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I have nothing to add other than this sounds like an ongoing conversation I have with my wife.

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"I swear I didn't mean for it to land in your eyes!"

Bad barrel? Overcharged load? Probably both!

Do you have a muzzle brake?

I don't have a lot of experience with AR accurizing.

With bolts I think one of the biggest factors is setting the bullets nearly out to the lands.

Does that apply at all on this platform?

Have you checked this out?

https://texags.com/forums/34/topics/3323362/replies/63103327

"Why'd you go with the shorter barrel?"

Have you faced/trued the receiver? Checked crown? If you are in Houston and want to try it i can lend you my ptg receiver truing bar.
It may just be finicky and need more workup too. 3 bullets and 3 powders= 3 loads? 9? Or multiple charges/coals in each combination?

You would be better off with a Marlin 30-30

Newoldarmy said:

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I don't have a lot of experience with AR accurizing.

With bolts I think one of the biggest factors is setting the bullets nearly out to the lands.

Does that apply at all on this platform?

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Limited on OAL by the magazine

1.5" grouping at what distance?

1.5" is far from a terrible gun. Definitely enough to to kill animals with.

To respond to some questions/ comments (many of which are in the OP)

I have tried two different factory rounds, Alexander arms 120 NBT and Hornady 123 SSTs. As far as handloading I have tried 3 powders: A2520, TAC and H335. Three bullets 120 Nosler BTs, Speer 120 HotCors and Sierra 120 Pro Hunters. After ladders I'm guessing at least three loads per bullet/ powder combo. If my math is right that's at least 27 different handloads. I don't shoot hot (overcharged) loads. I shoot off a portable bench but have no trouble keeping several other guns inside an inch on it. I don't have any rail screws pressing on the barrel. Yes, the receiver has been trued (lapped). I went with an 18 inch barrel because I wanted a quick handling gun that would work in the woods as well as coming up off my truck floorboard for quick shots at escaping hogs. The trigger is good and have tried the upper on the lower that goes on my .300 Blk which shoots dimes. No muzzle break, just a standard Alexander Arms flash hider. And yes...I might as well shoot my Marlin 336, It groups almost as well.

What's the twist? Maybe it is having trouble stabilizing the 120s? Can you get your hands on some varget or 4895?

swampstander said:

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To respond to some questions/ comments (many of which are in the OP)

I have tried two different factory rounds, Alexander arms 129 NBT and Hornady 123 SSTs. As far as handloading I have tried 3 powders: A2520, TAC and H335. Three bullets 120 Nosler BTs, Speer 120 HotCors and Sierra 120 Pro Hunters. After ladders I'm guessing at least three loads per bullet/ powder combo. If my math is right that's at least 27 different handloads. I don't shoot hot (overcharged) loads. I shoot off a portable bench but have no trouble keeping several other guns inside an inch on it. I don't have any rail screws pressing on the barrel. Yes, the receiver has been trued (lapped). I went with an 18 inch barrel because I wanted a quick handling gun that would work in the woods as well as coming up off my truck floorboard for quick shots at escaping hogs. The trigger is good and have tried the upper on the lower that goes on my .300 Blk which shoots dimes. No muzzle break, just a standard Alexander Arms flash hider. And yes...I might as well shoot my Marlin 336, It groups almost as well.

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You might want to give Barnes TSX or TTSX bullets a try. They tend to shoot better with a pretty good jump to the lands. Barnes even recommends anywhere from 0.0015 to 0.0030". I reload for 7 different bolt action rifles and my most accurate load in four of them are with Barnes bullets.

Charismatic Megafauna said:

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What's the twist? Maybe it is having trouble stabilizing the 120s? Can you get your hands on some varget or 4895?

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I have Varget but have not tried it in the Grendel. I had some H4895 and to be honest, I might have used it for the Grendel. I went on about a 4 year reloading hiatus during an extended remodel and managed to lose all my notes. Twist is 8.75 I think.

How have you adjusted your gas block? I read somewhere that overgassing diminishes accuracy so i adjusted mine down to where it won't cycle, then open in tiny increments until it just cycles reliably. I actually lost a bit of accuracy on that last click but still shoots under an inch with hornady black

swampstander said:

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I went on about a 4 year reloading hiatus during an extended remodel and managed to lose all my notes. Twist is 8.75 I think.

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I hear you on that. 2 kids and a move since i reloaded and hit the range regularly

Charismatic Megafauna said:

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How have you adjusted your gas block? I read somewhere that overgassing diminishes accuracy so i adjusted mine down to where it won't cycle, then open in tiny increments until it just cycles reliably. I actually lost a bit of accuracy on that last click but still shoots under an inch with hornady black

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Set my gas block exactly this way. Was way overgassed before I added the JP.

I may have missed this in the thread, and I hate to make this implication, but.....have you had anyone else shoot this rifle? I like to sight in with a group of friends so that if we have issues, we can all take turns shooting the same rifle and figure out if its the indian or arrow.

Gas Block
Buffer / Spring
Barrel
Barrel nut torque
Trigger
Optics / Mounts

BrazosDog02 said:

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I may have missed this in the thread, and I hate to make this implication, but.....have you had anyone else shoot this rifle? I like to sight in with a group of friends so that if we have issues, we can all take turns shooting the same rifle and figure out if its the indian or arrow.

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Yes in OP

TX_COWDOC said:

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Gas Block
Buffer / Spring
Barrel
Barrel nut torque
Trigger
Optics / Mounts

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Not sure exactly what you are asking but optics, gas block, trigger and barrel are all addressed above. Fore end, scope mounts and barrel nut all torqued to specs. Buffer and spring are DPMS but, again, this upper has been shot with other lowers with the same result. As an aside, this lower has been shot with other uppers with no drop in their usual accuracy.

OP,

I don't know why everyone is having a hard time reading what you have already tried. I think you already know what your realistic options are: continue load development or move on to either a different barrel or completely new upper.

Sometimes quality components just don't pan out. I also would not be happy with groups larger than 1 MOA. I do think the number of rifles on the internet that are "1/2 moa" or better is a lot more than the number of rifles that really shoot that consistently on the range.

Go to the range with 5-6 boxes of different factory ammo off the shelf. Different projectiles, grs, etc. find the one that patterns best, and go with that. Then tweak powders etc if you're a hand loader.

Charismatic Megafauna said:

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What's the twist? Maybe it is having trouble stabilizing the 120s? Can you get your hands on some varget or 4895?

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My 12" shoots the same weight bullets no problem… it's 1:8

I'm sharing my approach to trouble shooting an inaccurate gas rifle.
For perspective, here's a Grendel build with factory Hornady Black:

Yea thats a uh pretty accurate gun you got right there.

Definitely pretty legit.

Precise, not accurate if he was aiming at bullseye.

Yes, that was shots 2,3 & 4 after getting on paper. The customer reports that he sleeps with the rifle it's so fun to shoot.

TX_COWDOC said:

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Yes, that was shots 2,3 & 4 after getting on paper. The customer reports that he sleeps with the rifle it's so fun to shoot.

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