308 AR bolt problems. Dragging aginst upper wall

[HRnightmare]

Several months ago I bought a new PA10 308 lower receiver, upper receiver and a PSA BCG

It wasn’t until Friday that I received the last part and assembled the firearm. I had trouble getting the bolt in the upper receiver. It seemed to be too tight. I had the bolt sitting in a Ziploc coated in FP10 gun oil for several months. When I tried to charge the bolt in the gun I was met with significant resistance. I pulled it out and rubbed gun lubricant on the inside walls. It helped a tiny bit but it is still very tight. I charged it back and forth several times to see if it loosened up and you could smell the grinding metal. When I pulled the bolt out it has several scratches down the sides.

I fear that if I continue to do this, the bolt is going to remove metal from the upper receiver and ruin the tolerances.

Should I continue to try and get it too loosen? Several years ago when I built an 9mm AR SBR I had the same sort of problem but the issue was the charging handle hitting the AR castle nut. That was easily fixed with a piece light sandpaper and a few minutes in front of the TV. This is a very different case so it seems.

I have contacted PSA but as anyone who deals with them knows, they are slow to email back. I tried to call a few times but can't sit on the phone all day at work.

Any suggestions?

 

[dogmush]

Just to make sure, is it rubbing the upper, or the reciever extension?

The fit of the upper to the BCG is supposed to be so loose, I wouldn't even call it "a fit". The BCG should drop in without touching. Either something is badly out of spec, or something is assembled improperly.

As always, pics of the affliction can help us diagnose.

 

[Jackal]

Something is out of spec, either the upper or the carrier. I'd email PSA and see what they recommend.

 

[HRnightmare]

Nothing can really be misaligned due to assembly in that manner. I did email PSA. I will try and call again shortly.

HOWEVER... after careful re-evaluation what it is is the BCM charging handle is rubbing along both corners AND along the top of the upper.

I am going to charge the handle a few hundred times and see if the problem begins to fix itself. If it is tight because of that I am not worried as I know a few rounds thru the trigger will fix it.

 

[Jackal]

Oh, so the carrier doesnt drag without the charging handle installed?

 

[HRnightmare]

Yes. I am thinking I may have a not straight charging handle. It seems to get caught up in the same position every time.

The charging handle is a BCM gunfighter and is brand new but the top and angled sides are completely worn down now to the silver metal . I am not concerned with it as far as looks go.

I think it needs to be shot a few times to loosen it up.

 

[HRnightmare]

I am at nearly 400 "charges", no actual firings and the charging handle still drags significantly against the receiver. You can smell the metal rubbing and if I charge it back and forth fast enough you can literally see the dust. The edges and top laser etching of the BCM logo and flag are nearly completely warn off.

 

[bikemutt]

If you have another CH laying around that could help isolate the problem. Barring any dirt or shavings in the CH keyway, sounds like an out of spec upper.

 

[Tirod]

No possible way an aftermarket charging handle could be the problem?

There are issues with AR10's - first, there is no "milspec" on them, some makers share a common dimensional pattern - others don't.

Therefore, there is no guarantee that some other part is compatible.

In this case, the BCM gunfighter handle doesn't fit the upper. No guarantee any of them will if their dimensions aren't compatible with the upper maker's dimensions. AR10's don't share common dimensions the way AR15's with a milspec TDP do.

Quit trying to make it fit, check a different handle to see which do. Neither should ever be chewing off the finish to accommodate the other. Changing handles should be the preferred choice, less work and less expensive.

Also goes to the high dollar handles offering a solution to a problem that rarely exists, and the platform already had a bolt hold open which is the preferred method of chambering a round. All the charging handle can do is retract the bolt far enough to lock it in place. It has to be asked, what are we trying to do by beefing it up when all it does is retract the bolt?

The M16/M4 hasn't had significant changes in 45 years.

If no other charging handles seem to fit, then maybe it is the upper, which would be a very rare circumstance. Don't know how the channel is milled in the upper, but given CNC programming and mill end sizes, there's very little reason to make one substantially smaller than the hundreds of others in that batch.

The charging handle is just as suspect.

 

[HRnightmare]

I suspect the handle as well. I am waiting for another option to arrive in my gun shops hands to try. In the interim I reached out to BCM and am awaiting a response.

All of my rifles have std charging handles except the 5.56 SBR with the suppressor. That one I added a PRI because it significantly decreased gas blow back.

I went with the BCM simply because I wanted to shoot the gun and it was the only one I could find locally. Turns out my schedule changed and I did not get to shoot it anyway.

 

[scythefwd]

can you drop the charging handle in without a bolt attached and have it drop freely into place with the rifle shotgunned?

 

[castingdonkey]

I just got done building a PA-10. I too had a charging handle issue but not quite like yours. The one that came with the rifle(no name Brand) had a really stiff spring in it and the latch would catch the receiver before the charging handle would catch the bcg. I borrowed my buddies Winham arms charging handle and the problem went away. One issue that could be causing you problems is that PSA seems to be working the bugs out of the PA-10 after releasing it and the tolerances may have changed over time.

Side note I bought my buddy a BCM gunfighter for helping to diagnose the issue with mine and I kept his charging handle. I tried the BCM in my PA-10 and it works great. I would just wait and see what Palmetto says.

 

[HRnightmare]

Interesting. Thanks for the info castingdonkey. HOWEVER, you completely just ruined my theory. haha

Bravo Company responded back that they think the handle might not be compatible with the PSA PA10.

I am waiting on PSA's confirmation. I ordered a generic no name charging handle to see.

I am an idiot and threw out the packaging because in all the AR15's I have built I never had this issue and didn't think it even existed. Luckily Bravo Company was nice enough to say that if it is NOT compatible they will replace it for free with another type of handle OR replace it with a new one of the same kind in the packaging.

Might not solve my dilemma but definitely says something about the company.