LR-308 barrel and upper receiver fitment issue.

[ElroniO]

I am building a precision rifle on the LR-308 DPMS platform and ran into a fitment issue. I am using an Odin Works 22inch 6.5 Creedmoor barrel on a New Frontier Armory C10 Side Charging upper receiver. When the barrel is inserted into the upper, the barrel lug that fits into the receiver slot doesn't fill the whole thing. Therefore, when I go to tighten down the barrel nut the barrel twists ever so slightly which makes the BCG not go in because the bolt doesn't align with the grooves in the barrel extension.

What can I fill or add to make the barrel stay in its place?

Thanks for any help.

 

[clm2112]

I am building a precision rifle on the LR-308 DPMS platform and ran into a fitment issue. I am using an Odin Works 22inch 6.5 Creedmoor barrel on a New Frontier Armory C10 Side Charging upper receiver. When the barrel is inserted into the upper, the barrel lug that fits into the receiver slot doesn't fill the whole thing. Therefore, when I go to tighten down the barrel nut the barrel twists ever so slightly which makes the BCG not go in because the bolt doesn't align with the grooves in the barrel extension.

What can I fill or add to make the barrel stay in its place?

Thanks for any help.

Yes, you can place a shim next to the barrel extension locating pin to align it if needed. It will not hurt anything. The pressure of firing is contained within the steel bolt and steel barrel extension, so the fit of the aluminum upper receiver to the barrel extension is not super-critical.

A little wad of aluminum foil work pretty well. Same as if you were assembling an AR-15 upper. You are correcting a tolerance problem with the aluminum slot.

 

[Stephen G]

Pics?

 

[Stephen G]

Does the flang rest solidly against receiver?
Does The alignment barrel pin go into alignment slot, just doesnt slide home?
Does the pin not fit alignment slot causing barrel flange/ shelf to remain 1/8" off receiver?
Pics would really help.
If pin slot on receiver is too narrow, you can use a jeweler's round file to open it up. Using cation not to enlarge the slot too wide. Use tapered point of file, not full width of file.
If barrel doesn't reside solidly against the receiver 360° you are Not going to get any precision out of it and it a hazard.
Again pics help alot. Barrel inserted into receiver from top looking at pin/ slot fitment

 

[ElroniO]

Here is a picture to help identify the issue. I have circled the space that needs filling.

 

[ElroniO]

Using a shim sounds like a good idea.

Someone else I talked to mentioned using jb weld metal paste or puddy.

I dont really want to make any permanent changes though if I don't have too.

 

[Racer88]

Not my wheelhouse (building rifles), yet. But just wanted to welcome you as a new member.

Thanks for joining the forum and participating by posting! When you get a chance, please write up a quick “introduction” (or RE-introduction if you were a former MGB forum member) of yourself over in the Introduce Yourself! section. Tell us about yourself, your building experience, and how you found the forum.

Jump into other threads, too! Come on in... the water's fine!

 

[Stephen G]

I cant get the thumbnail to load a full size pic.

 

[Stephen G]

I misunderstood your initial post.

Doe the bolt carrier group lock and unlock at all?
Im curious if the barrel is seated deep enough. Too shallow causing the issue. Ive never had 1 give me issue due to a slight wobble in pin channel.
Ill have try later to look at pics- storms etc bad service

 

[Faster821_]

Examine the feed ramp alignment when determining the final rotational position.
I have same problem and watching this thread for a solution.

 

[ElroniO]

I took the advice to use a shim. I actually had some scrap aluminum from a floor transition strip I cut a small piece. Pounded it flat with a mallet and then trimmed it to size. Carefully placed it in the gap and tapped it in with a small punch. Once it was in place I folded it over low enough to fit the barrel nut around and screwed it together. Works great.

Thanks for all your suggestions.