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4/18/2021 9:59:29 PM
Posted: 5/10/2008 8:40:10 PM EDT
Click here to view pictures

I have been having trouble with my new build. I will be able to fire a round or two. But then things jam up. Above link shows what the rounds look like after getting jammed up.

I am using rebuilt mags.

I have cleaned and lubricated bolt and carrier.

I have made the extra turn on the mag release. Still have problems.
Link Posted: 5/10/2008 11:00:25 PM EDT
What are the specs on the build?
Are you loading the mags to capacity?
Have you tried other magazines?
Link Posted: 5/11/2008 12:14:38 AM EDT
Link Posted: 5/11/2008 9:32:01 AM EDT
20" bushmaster chrome lined barrel
A1/C7 upper from PK firearms
Bushmaster bolt and carrier

Cleaned and lubed with CLP before firing.
I have tried different mags.

I have not tried firing with one round in mag to see if it locks back.
Link Posted: 5/11/2008 2:15:10 PM EDT
Link Posted: 5/11/2008 3:34:28 PM EDT
I'll give that a try and get back with ya. Thanks
Link Posted: 5/16/2008 4:48:42 PM EDT
Made a quick trip to the range this afternoon.

I put 1 round in a mag and fired. I did this 3 times. Pics below show what happened 2 out of the 3 times.

Link to pictures

Link Posted: 5/16/2008 10:18:47 PM EDT
Link Posted: 5/18/2008 7:38:12 AM EDT
Thanks, I will check each of your suggestions.
Link Posted: 6/3/2008 11:56:57 AM EDT
I have a similar problem as akray, this is a custom build M-4 kit from M-A parts, I have tried new and used mags even my Army issued mags also tried a different bolt and adjusted the mag catch tighter. My rifle is not short stroking it cycles fine but is causing a lot of damage to the rounds as they load. The rounds look just like the ones in the first photo posted by akray but when a full mag is used (28 rounds) the bullets are even being bent at the top of the case just before it begins to neck down. This is leaving to distinct scratches on the bottom of the case, the bottom being the bottom of the case when it is loaded in the mag, the top being the visible part of the round from the top of the mag. The scratches are about 3mm apart and consistent, I think they are from the star chamber. The rifle fires and cycles fine and is fairly accurate these scratches are not as bad with one or only a few rounds in the mag but the more rounds in the mag the worse the scratches and bending or the bullet. Wolf ammo seems to not scratch much, probably due to the steel case, used Remington UMC and also so hand loads with Winchester cases, all had the same problems that had brass cases.

                                                           Thanks in advance for any help.
Link Posted: 6/3/2008 12:35:27 PM EDT
Link Posted: 6/3/2008 1:50:20 PM EDT
Thank you for the welcome, Here are some photos. Notice how the bullet and case are bent!

Link Posted: 6/3/2008 3:55:24 PM EDT
Link Posted: 6/3/2008 5:24:34 PM EDT
Been there done that, looks like bad mags.  Please don't say there USA mags.
Link Posted: 6/4/2008 11:27:09 AM EDT
Do you think the low feeds could be a result of the lower reciever not holding the mags at the proper height? What would you recomend to use to remove the burs on the feed ramps/star chamber?
Link Posted: 6/4/2008 12:50:31 PM EDT
Link Posted: 6/4/2008 1:43:38 PM EDT
I am using USGI and Colt mags that have been working fine in my issued Colt M4 so I dont think its my mags.
Link Posted: 6/4/2008 5:39:24 PM EDT
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