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Cannot get the AR-10 to group

scotchy

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Hello everyone,

Getting extremely frustrated with handloading 308 Win for my AR-10; a LaRue 18" PredatAR barrel in one of their ultimate upper kits they were selling back in 2019 matched with a LaRue lower. Assembled at their factory, promise I didn't stick chewing gum in the barrel extension, no wobble between the upper and lower, runs fine when you aren't forgetting to over cam the dies.
I am not the best shooter in the world but competent enough at 100 yards shooting from a bench rest. I cannot for the life of me get a load that's even 1 MOA, let alone sub MOA out of this rifle.
I've tried commercial once fired Winchester .308 Win brass and Lake City 7.62 brass (fired from the same gun) full length resized, annealed with an induction annealer, trimmed on a Giraud, primer pockets cleaned and primers (CCI Large Rifle or the military 7.62 primers depending on availability) seated appropriately.
Projectiles were 168gr Matchkings and 168gr Hornady BTHPs all seated to 2.800, powder choices were Varget, BL-C2, CFE223, and TAC. Powder loads were never overly high or low; typically in the 42-44 grain range and with every combination I'd do ladder loads stepping by .2 or .3 grains. - my SD for velocity typically came in at around 20 to 30. I used an electric powder measure and would measure powder loads twice with an analog scale along with the digital to make sure it was as close as I could get. Did not crimp.

Groups were 5 shots and every time it came out at 2.5 to 3 MOA, not chalked up to "flyers". Often would see vertical stringing up and to the right.

The barrel's supposedly sub-MOA capable but I'm starting to suspect that it's a gun problem at this point. All I've got left is trying to just use virgin brass and get a trimmer for the projectiles to see if I can make them uniform.

Any thoughts or glaringly obvious things that I'm doing wrong?
 

12v71

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Have you run any commercial ammo through it as a test? I have one FAL that loves PMC bronze 147gr. FMJ. I use that as a control benchmark.
ETA... I had a very expensive custom shop REM 700 .22-250 bull barrel that would do the up and right stringing as the barrel warmed up. You may just have a shit barrel with some locked up stress.
 

JDK15

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Here’s a bunch of stuff to take a look at with the rifle itself. I don’t think its a problem with your loads.

Take a look at the projectile and case after being fed from the magazine. If they are getting chewed up by the feed ramps that can be an issue. It could be from one side or the other so be sure to look at both. Measure the COL and see if the bullet is getting pushed back. You can also try single feeding rounds into the chamber to see if that helps. Make sure your muzzle device and barrel nut are tight. Make sure the handguard isn’t touching the gas block and make sure any accessories you have attached to it don’t have their mounting screws protruding far enough to touch the barrel or gas block. Take a look at the crown and make sure there are no dings or burrs. Make sure your scope/mount is tight and mounted properly. Try a different scope if you have one to make sure the optic isn’t the issue.

If one of those things doesn’t fix it I’d send it back to larue. Almost anything else would be a manufacturing defect that would require professional gunsmithing or major parts replacement to fix, so I’d let them deal with it before throwing your own money at it. I’d also recommend using factory ammo while troubleshooting so you have a consistent baseline. Federal GMM 168s shoot well in just about everything.
 

hkshooter

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Dude, that's about par for the course.
What he said ^.
And is why I won't bother with an AR10.
Buddy of mine spent a couple of years buying hi dollar AR10 types, developing loads, testing, drive time, range time. In the end he gave up, said screw it and sold them all. The best he said he had was an old Remington AR10 type. Told me it was actually a relabeled DPMS, said it was the most consistent of any of the type he had tested. His trails also included POF and a Knight SR-25, his first of the type.
Today he shoots an AR in 6.5 Grendel, loves it, shoots 1/2 MOA or smaller, hunts hogs with it.

Edit: He did finally settle on an AR10 type. A MegaArms Maten, matched upper and lower, home made hand guard, JP Ent Super Match barrel. Basically he parted together his own AR10 type. Shoots his reloads into .75 at 100. NOT surplus worthy or easy on the parts availability. Target gun only, not a SHTF gun.
 
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TerryN

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Uniforming the bullet meplats is wasted effort for 100 yard groups; 1,000 yards and beyond, maybe. I will make two suggestions; 1) try a good factory load like Federal Gold Medal Match. If it won't shoot good groups with that, it won't group; 2) consider removing your muzzle device. If it's too tight, it will constrict the muzzle and make the barrel throw shots. My guess is that you just got a crappy barrel. Every barrel maker turns out one every now and then.
 

scotchy

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I will be picking up some Gold Medal Match and giving it a try. The info on the meplats is very helpful as I was considering blowing more cash on a pencil shaver. Really really hope it's not a barrel issue as I have no idea how good the warranty (assuming it's even covered) will be on this 4 years out.

Appreciate all the feedback. I thought I was going crazy. If it's normal I can settle for less and just produce generic "FAL food" and zero all my non-precision .308s around the one load- though the whole accuracy promise from the manufacturer (and price tag) does irk me if it's not true.

Tell about the gas block, trigger, buffer spring, and furniture. Can you adjust the gas any?
Rounds eject at around 3 to 4 o clock and I don't think it's overgassed. The furniture is whatever LaRue's proprietary rail is along with their RAT stock, though I swapped this for a Magpul K stock because it was heavy. Trigger is a MBT-2S. Gas block is some proprietary LaRue thing, spring is I think a sprinco red. I am confident this isn't an issue of gas tuning or dwell time nor some major ergonomic issue that's impeding my ability to shoot as I'm really just ensuring the gun doesn't move as it sits on a bunch of blocks at the range before pulling the trigger.
 
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scotchy

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Bad news, gents. I just suck at reloading.
Bought a box of 175gr Gold Medal Match and fired a 10 round group after a very thorough barrel cleaning. First shot went wide because I didn't patch the oil out enough, but the remaining 9 ended up in a quarter sized group. I was rushing the group, too- barely 4-5 seconds between shots. Hot barrel.
Going to pull down some of the ammo and weigh the powder charge then use them as a sample group to compare my loads as far as external dimensions go- if nothing seems out of the ordinary versus my brass after it's been prepped then I've really got nothing left to stand on.
 

Papadoc

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Scotchy,
It looks like you had bad luck with the 168gr rounds, but using some 175gr it is shooting good. It has been my experience that any rifle can have a similar issue, likes some bullet weights, hates others. I think that is the case here, this rifle likes 175gr bullets. Have you tried any M118LR? Mil-spec OTM precision ammunition with 175gr bullets.
 

otis61

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This ^^^

Even two of the same rifles made one right after the other might, and most times do, like different loads, and, or bullets. That’s the fun part of reloading. Finding the right load. It can be done.
 

ArtBanks

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Great thread.
Couldn't figure our why my lawn mower ran so bad until someone mentioned it was designed for gasoline, not the diesel I had been trying to run in it. Glad you figured it out. Whatta Hobby!
 

scotchy

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I'll be honest, I got the 175grs because they were the only box left on the shelf at my poorly stocked LGS- going to try with 168gr GMM before I go out and start buying even more junk for pipe stuffing. I haven't put any precision 168grs through this rifle so I'll want to double check this first. I have a lot of 168gr projectiles remaining and would like to find some use for them as selling ammo components locally is rather difficult (not legal reasons, more demographic)

While I can "appreciate" the "appeal" of finding a perfectly tuned load for one rifle, I have a lot of .308s and a LOT of .308 brass. I would like to have a pocket recipe for a consistent 1-1.25 MOA load that isn't picky between rifles- I understand 1 MOA ammo through a 3 MOA rifle does not make 3 MOA groups, this is a scrupulosity thing- and short of devil magic shaman powder that the Federal people keep hidden in a crypt somewhere, these components are available on open market.
After churning out a thousand or so of these loads and settling my curiosity I'll be willing to focus on tuning handloads. Will also buy a Tikka or some other bolt gun so my left arm doesn't look disproportionately built after full length resizing every single case.

Maybe the AR10 can not relate with the other firearms in " Group " or they don't speak his language 🤔?

Has AR10 seen many other social workers he could relate with?
I have a second AR10 which uses a shorter pencil barrel, but outside of this all my .308s are FALs so trying to get sub-MOA groups with them would be losing a race at the gate. The other rifle's barrel profile was selected due to its weight and once it heats up I'd anticipate similar or worse accuracy to the other semis.
 

scotchy

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Current plan is to get another 20 rounds and pull some of the ammo down, take measurements of the brass vs my loaded ammo, measure powder charges, then try changing components between them. Swap the projectiles, use the GMM projectile and powder in my brass + primer, use my projectile+powder in their brass+primer, that type of deal. See if I can identify any explicit problem components.
I am a bit concerned that the primer choice may affect things and I'm unsure if you guys have any reports as to whether using non-"match" primers actually does affect accuracy or not.
 

scotchy

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I didn't see mention of a case gauge being used on your reloads. Is it possible you're nudging the shoulder back?
I use a L.E. Wilson case gage on my loaded rounds and they clear true. The press is set to over-cam a bit and since making this fix, my rounds no longer fail to feed reliably, but if you're suggesting that perhaps the brass is getting pushed too far in to the FL resizing die rather than not far enough, I'm afraid I don't know how to accurately measure this with calipers alone.

Primers definitely matter. But you probably won’t be able to see the difference in an AR-10. Well most AR-10.
I'm learning that everything matters with handloads, but some things matter more than others. The gun is not the limiting factor here. I'd be a bit surprised if regular CCI primers vs match primers were the make-or-break between an average of 2.5-3 MOA to ~1 MOA, but I'd be happy to be wrong.

Scotchy,
It looks like you had bad luck with the 168gr rounds, but using some 175gr it is shooting good. It has been my experience that any rifle can have a similar issue, likes some bullet weights, hates others. I think that is the case here, this rifle likes 175gr bullets. Have you tried any M118LR? Mil-spec OTM precision ammunition with 175gr bullets.
I think this may be the next step after I've put a box of the 168gr through it and finished the Frankenstein component swapping project.
 
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moonbat60

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I've got a reload that matches closely the load that Berger Bullets got on their website.

Mine uses a 175gr SMK instead of a Berger 175gr. OTM.

It is very accurate out of most .308's.
 

lew

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I'm learning that everything matters with handloads, but some things matter more than others. The gun is not the limiting factor here. I'd be a bit surprised if regular CCI primers vs match primers were the make-or-break between an average of 2.5-3 MOA to ~1 MOA, but I'd be happy to be wrong.
Just one data point, but my 5.56 handloads with CCI primers are giving me .7" ten round groups at 100m. I am about the laziest when it comes to brass prep, too. CCI primers are the most trouble-free I've come across.
 

scotchy

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Just one data point, but my 5.56 handloads with CCI primers are giving me .7" ten round groups at 100m. I am about the laziest when it comes to brass prep, too. CCI primers are the most trouble-free I've come across.
I also use CCI primers for my 5.56 loads, though my rounds group around 1.25" as they are loaded to near max pressure; they're meant to be duplicates of MK262. I like them, but with how irritating this project's been I'm open to any possible avenue for change.
 
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