Troubleshooting an Upper

[Tim_WNC]

I picked up a 6.5 Grendel upper on here last week that has been...disappointing. Looking for tips to trouble shoot.

18” Wilson Recon barrel
Odin works AGB
Warcomp brake

I was told only 80 rounds through it. I’ve run about 75, all with results similar to the attached images.

It cycles perfectly, piles brass up in a nice little pile right at 4 o’clock.

1st image is Hornady SST 123 that came with the upper. 4+” @100

2nd is American Gunner 123 also at 100.

Shot from a solid bench, with a mechanical front rest and quality rear bag. Burris XTRII at about 12x. This scope was repurposed from a .308 and is in a LaRue QD Mount.

The lower has a PRS stock and Geisselle trigger, this has been my DMM lower for a couple years with a .223 upper.

where do I start? Tear it down and true the receiver face? Remove the muzzle device? Or??

for sake of argument, let’s assume the shooter (me) is plenty capable of sub-MOA accuracy.

 

[Tim_WNC]

 

[deersniper]

I would remove muzzle device and also crank down on the 3/8 nuts on the Larue mount so it is tight tight

 

[aslrookie]

Remove muzzle brake, make sure barrel is not touching the rail or your shooting rest, check mount tightness on your larue for receiver and scope rings, shoot at least a full box of one type of ammo

 

[The DFC]

Simplest things first-I guess I would repeat with different ammo including bullet weights.

 

[TimK]

Make sure nothing is touching the barrel inside the hand guard. That’s shockingly bad accuracy. Something is badly wrong.

 

[Yondering]

Agreed something is badly wrong. Removing the muzzle device is a good place to start; a poorly aligned brake can really mess with accuracy. Is this a cheap upper, like Bear Creek or something?

Things like truing up the receiver face are not the problem, it doesn't make that much difference.

However - I'd pull the handguard off and verify the barrel nut is reasonably tight. Not gorilla tight, but I've run into a couple factory built uppers with barely tight barrel nuts. Had one try to unscrew in my hands when test firing, the handguard and nut started turning, only stopped by the gas tube. That kind of thing can cause the results you're seeing.

Check that everything is tight between the barrel and scope. That means every connection between those parts - barrel nut, scope mount screws/nuts, scope ring screws, etc. If you've ruled out all of those things, and the barrel isn't touching something, then it's probably either the scope or the barrel itself. The scope is a likely culprit; test a different scope before replacing the barrel.

 

[Ravenworks]

Take a picture of the Warcomp.
I run several of them and don't have issues with them

 

[Tim_WNC]

Take a picture of the Warcomp.
I run several of them and don't have issues with them

the Warcomp may be ever so slightly canted to the 11o’clock, but not much.

Check out the shit show of shims that were used to mount it...8 of ‘em.

I’ll throw on a simple thread protector for transport and I’ve swapped optics out.

Back to the range for day 3...

 

[Merle]

That's pretty normal actually. The big shim goes on with the countersunk end towards the barrel shoulder and then you install the comp and tighten by hand. At that point you use their clocking chart and add the amount of color coded shims until it clocks and torques correctly.

On another note, that gas block looks pretty close to the handguard.

 

[Ravenworks]

^^ He pretty much said what I was thinking.
I can generally get mine timed with 2 to 3 shims of various sizes.
Nothing wrong with testing the barrel with it off and nothing else on the barrel.
I find it really hard to see this kind of performance without finding the obvious.

 

[plt228]

I’d try some lighter bullets. My BIL and I got 2 Faxon Group Buy barrels( a run of 50 barrels). His would not shoot 123 at all. Better than yours but not as good as mine. Tried some 90gr TNTs and the groups dropped in half.
Any signs of the gas block hitting the handguard?
I’m real interested in your results because I was at Wilson’s webpage eyeballing the same 18” barrel since it’s on sale right now. Think I’ll have to hold off until you find out the cause of the poor shooting.

 

[The DFC]

That barrel should be a shooter.

 

[nn8734]

@WNC Seabee Have you reached back out to the previous owner to see if he had any thoughts or perhaps shot group pictures? I’d be curious to know if it had ever performed and if so, with what ammo.

Eager to hear about the results of your second range session...

 

[newguy2k3v2]

1. Look over Larue mount very closely. Clamping levers and the rings themselves.(I'm 0/3 with Larue mounts, never again)
2. Try without muzzle device
3. Disassemble upper and check barrel fit, barrel nut torque etc.

That's where I would start anyway

 

[nn8734]

1. Look over Larue mount very closely. Clamping levers and the rings themselves.(I'm 0/3 with Larue mounts, never again)
2. Try without muzzle device
3. Disassemble upper and check barrel fit, barrel nut torque etc.

That's where I would start anyway

Agree with the Larue Mount and wonder if the Larue “lever nut” tool was used to set the clamping force on those levers for the upper. If not adjusted, the levers will be loose on some pic rails, just right on some and super tight on others...

 

[Tim_WNC]

@WNC Seabee Have you reached back out to the previous owner to see if he had any thoughts or perhaps shot group pictures? I’d be curious to know if it had ever performed and if so, with what ammo.

Eager to hear about the results of your second range session...

Nope. His ad said he'd only shot out to 50 yards in prep for a hunt and only ran ~80 or so rounds through it. I have no reason not to believe him. But, if he was full of shit why own up to it now? Either way, it's on me at this point. It is what it is, I just want a shooter.

 

[Tim_WNC]

1. Look over Larue mount very closely.

Agree with the Larue Mount and wonder if the Larue “lever nut” tool was used to set the clamping force on those levers for the upper. If not adjusted, the levers will be loose on some pic rails, just right on some and super tight on others...

Huh. Never thought about using "the tool". My bad. I just kept tightening the nuts by hand until I had to use a good amount of pressure to close the levers.

 

[nn8734]

Huh. Never thought about using "the tool". My bad. I just kept tightening the nuts by hand until I had to use a good amount of pressure to close the levers.

Here are couple pics...I tighten until it locks up solid and takes some effort to remove.

 

[Tim_WNC]

I removed the muzzle device, inspected the crown (looks good) and went back to the range. A little bit better, but not acceptable as of yet.

I got a full 1" better with the 8x optic in a PEPR mount vs ~12x in the LaRue. It was cold and rainy....so maybe it IS the LaRue mount, either my not using it properly or it being a POS.

Next will be verify barrel nut torque (anyone have a BCM barrel nut wrench?) and putting the optic in a different mount.

I'll also pick up some different weight ammo....but I really really want it to work with Am Gunner as it's a decent bulk option!

 

[nn8734]

Nope. His ad said he'd only shot out to 50 yards in prep for a hunt and only ran ~50 or so rounds through it. I have no reason not to believe him. But, if he was full of shit why own up to it now? Either way, it's on me at this point. It is what it is, I just want a shooter.

I buy and sell literally thousands of dollars worth of “stuff” in the PX each year and prefer our PX to nearly any other source primarily due to solid deals and established trust across the SH community.

That said, it sucks when someone sells something that is not as advertised. If I had sold you that upper and came across this thread, I’d send you a PM to have you do some quick trouble shooting (all of which are outlined above) then if that didn’t fix it, arrange for the upper to be shipped back to me (if you desired) to have it diagnosed and fixed. Otherwise, I’d offer you a refund.

Then again, if I were the seller, it would have went out the door with a fully documented test target (5 shot group @ 100) with a few fired cases. This way I know it’s good to go once it gets to you.

That’s how I look at it but not everyone will agree.

edit: sorry this is happening and hopefully we can help you get it fixed.

 

[Tim_WNC]

@nn8734 While I appreciate the sentiment, I don’t believe the seller was nefarious. Sometimes shit happens. I’m very active (a moderator) on our NC\SC shooters forum and also do many many deals every year. I see a bunch happen in my moderator role as well. By and large, there are very few asshats in the shooting community.

 

[SupressYourself]

Like others have said, I would try different ammo. I never tried the American Gunner, but I could not get the Hornady custom 123 SST to shoot worth a shit. In two different uppers with two different (cheap) barrels, the Hornady Black with 123 ELDM shot roughly 1-1.5 MOA while the Hornady Custom with 123 SST shot like 4-something MOA. It was the damnedest thing. I'm glad I only bought one box of the SSTs.

 

[MontanaMan]

Take it down & do what Yondering said; try a known good scope..................if that doesn't fix it, then most likely it's the barrel.

I had a similar thing happen with a new BA fluted barrel once.....................it happens. There are a handful of barrel makers I buy from now; Wilson Combat & BA are not on that list.

YMMV

MM

 

[Tim_WNC]

Like others have said, I would try different ammo. I never tried the American Gunner, but I could not get the Hornady custom 123 SST to shoot worth a shit. In two different uppers with two different (cheap) barrels, the Hornady Black with 123 ELDM shot roughly 1-1.5 MOA while the Hornady Custom with 123 SST shot like 4-something MOA. It was the damnedest thing. I'm glad I only bought one box of the SSTs.
View attachment 7207568

So what load did you end up with?

 

[SupressYourself]

So what load did you end up with?

I actually swapped that barrel out for a 243 LBC, which was always the plan for that upper. I just shot it a bit in 6.5 mode while I was waiting on the 6mm barrel. Those two loads were the only ones I shot through the 6.5 barrel.
The other one is my brothers. He seemed to be ok with how the Black ammo shot, not sure if he's tried much else.

 

[redneckbmxer24]

I'd pull the whole thing apart, reassemble, and run some other ammo through it. The FGMM 130gr Berger and the Federal Varmint and Predator load are usually very accurate and would be good to try. If it still doesn't shoot then I'd venture to say it's just not a great barrel and I'd see if Wilson would take a look at it.

 

[USNavy06]

I removed the muzzle device, inspected the crown (looks good) and went back to the range. A little bit better, but not acceptable as of yet.

I got a full 1" better with the 8x optic in a PEPR mount vs ~12x in the LaRue. It was cold and rainy....so maybe it IS the LaRue mount, either my not using it properly or it being a POS.

Next will be verify barrel nut torque (anyone have a BCM barrel nut wrench?) and putting the optic in a different mount.

I'll also pick up some different weight ammo....but I really really want it to work with Am Gunner as it's a decent bulk option!

View attachment 7207552View attachment 7207553

I have a BCM barrel nut wrench. PM your address I’ll send it out tomorrow. I’m very curious on this barrel as I’m building a 6.5 Grendel and looked at this barrel as well.

 

[Tim_WNC]

I have a BCM barrel nut wrench. PM your address I’ll send it out tomorrow. I’m very curious on this barrel as I’m building a 6.5 Grendel and looked at this barrel as well.

Nice! Thanks!

 

[USNavy06]

Nice! Thanks!

Barrel wrench on the way. Let us know if anything changes.

 

[Tim_WNC]

It’s a Festivus Miracle!

Moved the scope (XTR II 3-15) over to a Burris PEPR Mount, properly torqued but not precisely leveled and eye relief a bit wonky.

I had 30 minutes to hit the range and came away with this group. American Gunner 123s

That really errant shot is 100% me. I pulled across the trigger instead of straight back. I knew it as soon as the shot broke.

If that 4 shot group is the new normal I’ll be ecstatic. Of course it’s only 1 group, but it’s given me hope!

FWIW, the Hornady SST (5 shot, 2.47”) and Black (5 shot, 1.47”) were better than before, but still worse than the Am Gunner.

 

[bfoosh006]

1. Look over Larue mount very closely. Clamping levers and the rings themselves.(I'm 0/3 with Larue mounts, never again)
2. Try without muzzle device
3. Disassemble upper and check barrel fit, barrel nut torque etc.

That's where I would start anyway

And since I can't tell... on the LaRue mount rings... always tighten the lower screws first, then the top ones.

I have seen LaRue's instructions somewhere saying this... and Matt LaRue has confirmed it.

 

[newguy2k3v2]

And since I can't tell... on the LaRue mount rings... always tighten the lower screws first, then the top ones.

I have seen LaRue's instructions somewhere saying this... and Matt LaRue has confirmed it.

Even then, properly torqued all 3 that I have had were prone to let the rings shift up and down on the base. It's a shit design.

 

[Sendit6.5]

any updates?

 

[Tim_WNC]

any updates?

Still need to get back to the range. Holidays with a bunch of family in town put me off task. Going to try getting back this we

 

[Tim_WNC]

This issue can also be caused by an undergassed gun, so I would work your block some.

Interesting. From prone, my brass piles up right at about 4 o'clock and approx 2.5ft from the ejection port. Undergassed?

If so...I'm running a 5.1oz rifle buffer and standard rifle spring. Throw in a lighter buffer or go to work on the block?

I've also thought about turning the gas off entirely, going single shot, to take that out of the equation.