I was at the range this weekend and had "a lot" of FTFs with a couple mags. The bolt was pushing the round forward but the round was getting caught on the front of the mag causing the bullet itself to get jammed back into the cartridge. I tried the other mags I had with me and had no problems whatsoever thus eliminating the rifle as the problem.

Anyway, after I got home, I used a round to more closely examine what the problem was. As I thought, the edge of the case is hitting the front of the mag. These mags have brand new green followers and brand new mil-spec springs. One mag is a NIW (well, was NIW ) Parsons and I don't recall the other but it's a USGI. I'm 99.9% sure the problem is with the feed lips.

My question is what do I do to fix this? Do I try to file a bit from the inside edge of the feedlips to smooth them out and remove a bit of metal? Or, do I slightly pry up the feedlips to give the round a bit more relief?

TIA.

If the problem mags have "new green followers and milspec springs", I would suggest doing the other half of the experiment and putting old black followers and used springs back into them, and then try them for function.  If you did not replace the followers and springs and do not have the originals, swap the followers and springs out of a functional mag, and put the followers and springs from a suspect mag into the "good" mag and try for function.

I mention this because a local shooter called me about a month ago, complaining about five mags he bought of one of the boards and how they weren't reliable.  They were 30s, looked refinished, had scuff-free green followers and "high power" springs.  I filled one mag and tried it in my Bushy carbine and it repeatedly jammed.  Having original springs and followers, I converted the same mag back to its original condition and the rifle burned thru 30 rounds without a hitch.

Culprit?  "High power" springs.  Man, were those stiff!  They had the same number of coils as a standard spring, but were about 1.375" longer in OAL, and the wire diameter was larger, too.  The extra (IMO, unneeded) force pushed the top cartridge too strongly against the feed lips, effectively increasing friction and preventing operation.  I eliminated the green followers by installing them on standard springs, and they worked fine.

Moral:  The components of an assembly or machine are specified they way they are for a reason.  In some cases, "more is NOT better," and this can apply to mag springs as there is obviously a limit.  Stiffer springs might be fine on an F350, but I'll take my AR mags truly Mil-spec, thanks.  Rant off.

Noah

Thanks for the response Noah.

Unfortunately, I don't have the original followers or springs. All the springs in most of my mags are exactly the same. I did replace some of the springs with the new-fangled chrome silicon springs. Some of the problem mags also have the orange followers that have recently cropped up. Basically, I have mags that work with new followers (green and orange) and new springs (both std. mil-spec and the chrome silicon springs).

I'll try swapping components out of a mag that feeds correctly but, considering all the components are the same (at least, they should be), I suspect the feedlips are still a bit too sharp.

Thanks again for the reply.

Matt:

Some mags that is a problem.  Strip the mag, take some fine sandpaper (320) and lightly polish the feed lips.  Being aluminum it won't take much to remove a few burrs that mich be causing the problem.  

Noah

When I was testing the mags at home, I was just sticking a single round in the mag then trying to push it forward by hand. After I was done, the round had little scratches (that I could feel) running along the length of the cartridge. That tells me that some of the feedlips are too sharp. I'll go through my problem mags and buff out those sharp edges then I'll try running a round through them again to see how they feed.

If that doesn't solve the problem, I'm going to swap springs and followers around.

Thank you again for the advice.