6.5 Grendel with Lilja barrel won't shoot straight

[AZgrendel]

Hello Hide, I don’t post online much but I’m stumped. Been shooting and reloading for my 6.5 Grendel AR for about 6 years. Im a machinist and have been hobby gunsmithing for 30 years but far from an expert. Recently replaced the Alexander Arms 18” barrel with a Lilja 16”. Started out with some OK groups 1 to 1.5 MOA on average. Seemed to like the Hornady SST and Shooters World Match Rifle powder so bought a bunch and started to refine a load. Every time I went to the range, the performance got worse. Thought it might be the scope so changed from the Athlon Helos 2-12 I was using to an NF ATACR 4-16 in quality mounts. No dice. Stopped using a suppressor to remove variables but no help. Performance went from bad to worse. I clean regularly with boretech and nylon brush followed by patches. Baby the crown and always use rod guide. I’ve done what I know of to give it best chance for accuracy. Barrel is bedded in loctite 609, receiver is lapped, nut is torqued to 50 ft lbs. Gas tube is tweaked to not touch receiver, AGB tuned to just lock open on last round. Everything to do with optics is torqued to spec and loctited. Everything on the gun is premium but 300 rounds in an it’s shooting 4MOA with the same loads the were 1 MOA at first. Nearly all groups have a mostly vertical dispersion with an angle high left and low right. Pretty sure it’s not me, I can shoot great groups with my other guns. Just bought a bore scope and it looks pretty good to me with the exception of the gas port which clearly has some buildup on it. Don’t know what normal looks like so hope someone can say if that looks problematic. Also, when I received the barrel the extension looked like it was produced in 1980’s china. I polished it up as best I could. I’ll add a pic.

What am I missing? Appreciate any suggestions. I’m loathe to ditch a new $450 barrel but the gun is worthless as is.

 

[TonyAngel]

Hey man, sorry to hear you're having such troubles. It really sucks to be where you are. Mixing all of the right ingredients and getting crap results.

It sounds like you did everything right. What I'd first do, is get someone else to shoot the rifle and see what happens. It might sound stupid, but you may have psyched yourself out with that rifle and are screwing yourself up.

Secondly, i know that Lilja has a good reputation, but they are not infallible and they will never again be my first choice for a barrel. You should give them a call or shoot em an email.

Still, did you check the headspace? Maybe try another bolt and see what happens. Are you sure that your mount setup is solid? I very recently had a similar problem and it turned out that one of my rings had micro fractures in the clamp. It looked and felt solid, but wasn't.

 

[hlee]

It looks like there is are some really nasty burrs on the feed ramps. Is that an optical illusion? If not, I have 2 questions…

1) What is causing that burr to form?

2) What is that burr doing to the bullets as they are fed into the chamber?

 

[37L1]

Try taking the copper out, also check for a carbon ring?

I have a Lilja in one of my 6.5 Grendel uppers, shoots great.

 

[Bevo]

Those feed ramps look NASTY. Get to polishing. Stay on Reb about the barrel, he’s slow to respond but should get back to you.

 

[AZgrendel]

It looks like there is are some really nasty burrs on the feed ramps. Is that an optical illusion? If not, I have 2 questions…

1) What is causing that burr to form?

2) What is that burr doing to the bullets as they are fed into the chamber?

Thanks, The pic is what the feed ramps looked like when received. I removed all burrs and roughness and polished the ramps before the barrel was first installed. I think your next point is what I need to look into next to see if the buildup on the gas port is carbon or copper. If it is copper, I think that is an issue. Appreciate the response.

 

[AZgrendel]

Hey man, sorry to hear you're having such troubles. It really sucks to be where you are. Mixing all of the right ingredients and getting crap results.

It sounds like you did everything right. What I'd first do, is get someone else to shoot the rifle and see what happens. It might sound stupid, but you may have psyched yourself out with that rifle and are screwing yourself up.

Secondly, i know that Lilja has a good reputation, but they are not infallible and they will never again be my first choice for a barrel. You should give them a call or shoot em an email.

Still, did you check the headspace? Maybe try another bolt and see what happens. Are you sure that your mount setup is solid? I very recently had a similar problem and it turned out that one of my rings had micro fractures in the clamp. It looked and felt solid, but wasn't.

Pretty sure mount is good. Checked it carefully initially, then took recently took off and rechecked. It's a BoBro twin clamp so there are some screws that can only be checked with scope off. I don't have gauges for the Grendel but will look into ordering some. I'm resizing for a very close fit. I do have another bolt, I'll try it.
Thanks.

 

[TonyAngel]

Man, honestly, I'd throw that borescope away. Lol. I had one at one time and all it did for me was get me DEEP into my head.

As for that buildup at the gas port, it's hard to tell if it's something affecting the bullet or not. Still, it would account for your groups getting progressively worse.

In any case, whether it's just a case of sloppy machine work or whatever, you shouldn't be spending time diagnosing a new barrel. Either it shoots or it doesn't. You should do your best to make it Liljas problem. Sorry, revisiting this is bringing back memories of my experience with lilja and apparently, im still feeling pretty salty about it.

 

[357Max]

Pretty sure mount is good. Checked it carefully initially, then took recently took off and rechecked. It's a BoBro twin clamp so there are some screws that can only be checked with scope off. I don't have gauges for the Grendel but will look into ordering some. I'm resizing for a very close fit. I do have another bolt, I'll try it.
Thanks.

What is that zip tie in the rail next to the gas block for?
You’ve got a few accessories added to the rail, make sure nothing in the rail is touching the barrel. I typically what to see no less than .030 clearance to gas block/barrel.

 

[dogman]

Isn't this the second time someone has posted a Lilja AR barrel with burrs?

 

[AZgrendel]

What is that zip tie in the rail next to the gas block for?
You’ve got a few accessories added to the rail, make sure nothing in the rail is touching the barrel. I typically what to see no less than .030 clearance to gas block/barrel.

Thanks for the suggestions. Zip tie was there to slide the extended Allen key for gas block into for transportation. Sinse been cut off. None of the Mlok mount are anywhere close to the barrel.

 

[hlee]

Isn't this the second time someone has posted a Lilja AR barrel with burrs?

I think it’s the same barrel…

 

[AZgrendel]

I think it’s the same barrel…

Not the same one. Saw the other post. I think his was worse than mine. I believe he received a replacement.

 

[Ernest 5.56]

Wonder if they would deburr the gas port if you sent it back? If that's what the issue is