This is the AR I built for long range. I’m anticipating building a 20" AR further down the road that will wear this Leupold scope, and this one will wear a lower magnification optic.
This is what it has on it (copy/paste):
Rainier Arms upper and lower
Rainier Arms Match 16" Mid-Length Barrel (.223 Wylde with 1in8 twist)
Vortex Flash Hider
Centurion Modular Rail
Leupold Mark IV 4.5-14x40 sitting in a Larue LT-104
Magpul UBR
BCM Charging handle Mod4 and pistol grip Mod1
Geissele Hi-Speed National Match trigger
Harris LM-S Bipod
Here is where the problem comes in. It won’t group for shit. I’m lucky if I get 7 MOA out of it at 100 yards. I’ve tried 100 rounds of my friends reloads, LC M855, Fiocchi Match, Wolf Gold, and a Winchester White Box. They all shoot like shit. I don’t think it’s me, my friend has a similar rifle, but with a GI trigger, and I group sub MOA with his rifle… with next to no trigger time behind it. Hell, I get better results with my Ruger American Rimfire.
I assembled this rifle from scratch and I’m confident that the barrel nut is on right and the scope is torqued properly. All witness marks are still aligned. I had some clearance issues with the gas block and the CMR rail, but I fixed it and have ~2mm of space, which should be plenty.
Anything I can start checking/trying before I disassemble this thing and try it again? I’d expect much better results from this barrel.
If you seriously want to have it diagnosed, you can send the upper to me. I can do a safety inspection, test fire, diagnostic, and corrective action; all recorded.
The rifle’s parts, and configuration should definitely yield accurate results.
If the barrel install was done successfully as you stated, then really the only thing that jumps immediately out is making sure you didn’t over torque your muzzle device on when installing.
The ammo you listed that you tried isn’t the greatest at all for precision/accuracy testing. That ammo most likely isn’t capable of sub MOA or close to it especially with stuff like m855(10rd groups).
Get some true match grade ammo…Hornady 55gr. Vmax is my personal “control” for 100yds.
Obviously I’d be inspecting my crown, and inside of the barrel as thorough as possible as well.
I agree with Trident82. Hornady 55g VMax should shoot really well. Hornady 68g match ammunition should also perform well.
Over-torqueing the muzzle device will have an adverse effect on accuracy. Muzzle devices on my high power rifles are screwed on hand tight and kept in place with Loctite Blue. On any other rifle, I torque the muzzle device on at the low end of the specified torque range.
What kind of groups does your friend shoot with your rifle?
I’m not sure if it’s over torqued or not. I’ll take it off and out it on hand tight, the flash hider is designed to tighten itself during normal use, so I’m not too worried about it coming off.
My buddy never shot for groups, we have a ?10"? gong at 600 yards that we were shooting at. He can hit it 9/10 times with some cheap match ammo.
I haven’t checked that, I’ll take a look when I get home.
How much clearance does your gas block have inside the handguard with the bipod attached? Could be shadows but it looks like you might have a barrel harmonics issue.
I had a larue SPR. My gun was spraying them too. I torqued down the mount so tight I could hardly close the levers and have to use the sling to undo them. That is what it took to stop it moving around. I removed it and replaced it with a fixed mount.
Personally - I’d remove all the variables. Take everything off the rifle - bipod, mount, scope mount etc and start with a clean rifle.
Start inspecting.
Begin at the muzzle.
Get a hand lens / jewelers loop (8-10x) and look at the inside edges of the comp/flashhider - look for bullet strikes. If the bullets are hitting the comp, you’ll absolutely see copper smudges.
If you can safely remove the comp/FH - do so.
Next check the crown. I doesn’t take much to damage the crown on a barrel. chips, gouges, burrs - all have enormous effect on accuracy. The crown is the (should be) the last thing to touch your bullet.
Not uncommon for a burr to remain after production crowning and when that first round goes down the tube, it tears a chunk of bbl off at the crown.
Assuming those aspects check out ok - verify that nothing is bearing on / influencing the barrel - hand guard / rail system is tight, bbl is properly mounted & clearanced etc.
If these check out - I would turn my attention to the scope / mount. If the mount seats properly and can be correctly torqued, then check the gas tube.
The gas tube should actually “float” in the hole in the fron face of the upper rcvr. There should be a tiny amount of perceptible movement 360 deg. The nipple end of the gas tube should enter the gas key without any binding / drag. Strip the bolt and turn the upper upside down - hold it parallel to the floor, now insert the stripped carrier - slowly point the muzzle down until the carrier starts to move - it should slide right onto the gas tubeat about 20-30 degs. If it hangs up there is some significant interference that needs correcting. If this all pans out - then I’d really start to look at the scope.
I have seen / diagnosed scopes that have had the living daylights beat out of them - they looked pristine, but had been used on various rifles that just beat them to death.
M14’s/M1A’s are particularly nasty when it comes to optics. I had a shooter bring in an M14 that shot minute of barn door. After looking at the rifle inside and out - I remounted the scope and dry fired the rifle on a grid target. Low and behold, just from the dry fire, the reticle jumped around and settled back down about 3-1/2 moa from where it was before I dropped the hammer.
This was a quality scope too (Leupold) - shit happens. The erector spring(s) went tits up. M14’s beat scopes in recoil, which they usually withstand AND counter recoil - that’s when the bolt/oprod slam back into battery. AR10’s are tough on them as well for the same reason. Airguns (spring type) are insanely abusive to standard rifle scopes.
Change the scope out - put some glass or even irons on the rifle that are known to function properly.
If all else fails - everything is tight, properly assembled, right dimension - you may just have a bad barrel. But my guess (without seeing the rifle) is that it is an issue with the comp/FH or crown or your optics.
I’d seriously consider sending it to Failure2Stop.
The scope is torqued to 30in/lbs following Larue Tactical’s instructions, the levers are relatively snug… not so snug that I need a tool to remove them, but snug enough that a kid would have problems opening them.
Sent it yesterday, it’s on vehicle for delivery right now. I couldn’t fit the bipod and scope into the box unless I went with a giant cubed box, hopefuly he finds what the issue is.
This. Every time I have an issue this is my first place to check for solutions. If a search doesn’t come up with anything good I’ll post a question. Every time I’m impressed with the help provided. It’s like a hidden gem of the AR15 world.