I started a thread about a week ago in here asking if PMC Bronze was giving anyone else issues as it did for me. It got moved to the Reloading and Ammo forum since it was…well…ammo related. However after experimenting with my rifle I’ve come to realize that it doesn’t seem to be an ammo issue. Essentially what’s been happening is that every other round or so results in a Failure to Feed malfunction. Curiosity got the best of me so after cleaning my rifle tonight, I loaded up a mag and started working the charging handle to eject the rounds. Just about every time I let go of the charging handle, the tip of the round would get wedged in the feed ramps and not fully seat in the chamber. I tried different mags and ammo but I still get the same issue. My upper receiver is a BCM middy with all BCM internals and a stripped S&W M&P 15 lower with a DPMS LPK. Any suggestions?
I think you should contact BCM and have them look at the upper.
Call BCM cause it sounds like manufacturing defect.
ETA: >.>
I think I’m going to give them a call tomorrow. If it helps at all here’s a picture of what’s going on:
2011-04-22 00.28.03 by V A Photography, on Flickr
What action spring and buffer are you using?
Standard carbine spring (as far as I can tell) and “H” buffer.
Any idea where the action spring came from?
I bought the spring, buffer, and extension tube packaged together in a bag from Virginia Arms back when I first started putting my rifle together. I didn’t know a lot about what I was doing back then however when I told the guys at the store what I was aiming to build that’s what was handed to me. Great store, great guys, so I trust their judgment.
What’s confusing me is that this JUST started happening last week. I’ve had the same setup since this past August and haven’t experienced this sort of malfunction till now. In fact, my rifle has functioned flawlessly until last weekend.
This could be from riding the charging handle. Does it do this when you use the bolt release or when shooting?
ETA: Nevermind, I saw that this happens while you were shooting.
It worked before? That changes things somewhat…
Have you measured the action spring? Even if you got it somewhere reputable there are sometimes bad heat treats… The best way would be to test it on a different lower then you can narrow it down.
ETA: Be careful cycling live ammo in your house, it’s like an accident waiting to happen. Also what the guy above me said^, pull handle all the way and just let go of it.
A lot of stuff can be ruled out if this happens while you’re just hand cycling the weapon. Something is slowing the BCG down to the point that it can’t get the round out of the mag and/or past the feed ramps.
Do you have any other lowers to try? How many rounds on that spring? Has anything in the lower (mostly relating to the receiver extension tube) worked loose?
I do not think that Virginia Arms would sell you a bad spring, but even good springs wear out with use. Of course, it could be something else entirely.
It doesn’t. However when I’ve been working the charging handle, I pull it back all the way and then release it to ensure enough force is being put on the round to seat it in the chamber. In other words I’m not keeping my hand on the handle when I’m trying to cycle the action.
I personally don’t have another lower to try but my buddy owns a LWRC that I could swap lowers with and try out. If I’m not mistaken, I’ve put at least about 1,200-1,500 rounds on the spring. Nothing seems to have come loose that I can tell.
JSTICFRALL quick question for you… take a look at the ejected cartridges you hand cycled and do you notice gouges on the projectile?
My BCM 14.5" carbine upper, which has previously run like a top with an LMT BCG, is exhibiting exactly what you’re describing… the cartridge gets hung up on the feed ramp during hand cycling.
I took the BCG apart, cleaned, and liberally oiled. It seemed to have help the situation. When manually cycling the charging handle, I find it best to firmly grip the charging handle and pull back all the way, and keep the hand moving back while releasing (if that makes any sense). I find that when pulling the charging handle all the way back, pause and then releasing causes the cartridge hang up sometimes. Not sure if this is normal.
Please let us know what you find out after speaking with BCM CS.
Funny you should ask! I was just showing my roommate the gouged projectiles. One of the brass casings even got a nice dent in the side.
I’m thinking the gouges in the projectile are caused by jamming across the star chamber.
I honestly have never noticed these marks until recently. Can other members comment on this, is it normal?
Sometimes shiny streaks but not gouges.
Is that barrel extension too far back into the receiver or is that an optical illusion? Look at the barrel extension where it protrudes past the edge of the ejection port. It must be my imagination or an optical illusion or what?
Definitely just an illusion haha
Measure the overall length of your buffer spring and report back.