PSA barreled AR15 Feeding Issues

[sentry1]

This is a new Barrett upper & PSA barrel/extension with M4 feedramps, and I'm having feeding issues.

The tips of the rounds are getting jammed in the feed ramps. I've tried PMAGs and USGI mags, same problem every time, and I'd say it's 4 out of 5 rounds get jammed like this. There's a whole lot of copper getting gouged off the bullets too, you can see it left on the feed ramps, and it's definitely noticeable on the copper jackets.

It seems like the feed ramp angle on this extension is not as shallow as the ramps on my previous upper, and the lugs around the feed ramps should be opened up a little wider for smooth feeding.

Is this just a break-in issue, or an actual problem?

P.S. I took the firing pin out before I set the gun up to take the photos, safety procedures have been observed.

<span style="font-weight: bold"><span style="font-style: italic">Edit</span></span>: Clarification - The tip of the bullet is getting jammed in between the lugs at the top of the feedramps.

 

[BDHershey]

Re: PSA barreled AR15 Feeding Issues

The feed ramps don't look like they'd be a problem to me.

I assume given that you say it's a Barrett upper and PSA barrel this may be a home build? What lower are you running it on?

 

[Mil.Dot]

Re: PSA barreled AR15 Feeding Issues

We ran into the same issue a couple weeks ago with a build for my brother-in-law - seemed to be a very small lip from the receiver ramps to the ramps on the extension, but not enough that it should jam.

We started systematically changing one thing at a time, to pinpoint the culprit (changed ammo, added lube, lightly lubed the buffer spring/tube, changed mags, changed lower). We had a number of different mags and several different lowers, which made it an easy job.

Ultimately, it seemed like it was a combination of several small things, with the primary culprit being a couple mags in combination with a firm buffer spring being just enough to not feed well. Once we put it on a well-used lower and known reliable mags, it ran great. after about 40 rounds we switched back to the new lower (Vltor A5 system and new mags), it continued to run like a top . . . never had that happen before and no problems since.

As I said, seemed to be just the right combination of things and just needed a little time.

Can you swap in a different lower?

 

[sentry1]

Re: PSA barreled AR15 Feeding Issues

I'm using an Armalite Eagle Arms lower, which I've been using a while now, and haven't had any problems with it and the previous upper. I kept the original lower, bolt and BCG, only swapped out the upper & barrel.

This upper was a home build, but not by me, I purchased it here on the Hide. The previous upper was built by an armorer buddy back at Quantico, so I guess I got a little spoiled there, with it working awesome from the moment he handed it over.

Anyways, I will see if I can borrow a lower, most of my shooting buddies use bolt guns. In the meantime, I'll try scrubbing and lubing everything that needs it.

 

[sentry1]

Re: PSA barreled AR15 Feeding Issues

P.S. To clarify, I think this where the actual jam is occurring. It's not the feedramp itself, rather, at the top of the feedramps, the spacing of the lugs on the barrel extension are narrow enough that the tip of the bullet is getting wedged in there.

 

[Temp9]

Re: PSA barreled AR15 Feeding Issues

Use fine grit (600 or finer) sandpaper and remove the sharp edge on lug/ramp.

 

[sentry1]

Re: PSA barreled AR15 Feeding Issues

Yep, found a pic of my old feedramps, definitely not as sharp or narrow as this one. Guess it's going to need a little fine tuning.

 

[*greenhorn*]

Re: PSA barreled AR15 Feeding Issues

dremel and a bit of shaving and mirror polishing will fix that