Thursday, June 9, 2011

How To Make a Magazine Lip Tool

I wanted a 5.45x39mm AR upper, to shoot some of that inexpensive Russian surplus ammo.  Scored a Spike's mid-length 5.45mm upper from AIM Surplus when they had some in stock.  I've come to find out though, that many of the C Products 5.45mm AR mags are crap.  Most of them work all right, if you load them half way.  However, if I load them with more than 20 rounds, and I got lots of feed failures.

Without getting too deep into the issues with the 5.45mm mags, I'll tell you that the feed lips were part of the problem.  I've been down this road before.

I guess it was back when the only pistol I had was a Ruger Mk.II, that a bullseye shooter told me how to make a mag lip tool from a carriage bolt to keep the Mk.II from jamming bullets into the bottom of the feedramp.

Brownell's sells a tool to adjust AR magazine feedlips for about $13, but a carriage bolt only costs about 60 cents.  It's just a matter of shaping the bolt into a tool.

I'm 90% certain that I made the tool for the Ruger Mk.II tool from a 1/4" bolt.  For the AR magazine tool, I bought a 5/16" bolt.  I could have gone a couple sizes larger, but it gets the job done.  I you have access to key stock, use that, and save yourself a few steps, but the carriage bolts you can pick up at most hardware stores for less than a buck.

5/16" Carriage Bolt, with the head annealed

You've got to cut the flange off the bolt, leaving you with the square. . . lug, at the head of the bolt.  Then you cut a notch in the "lug" to slip over the offending magazine lip and bend into the right shape.  That's about it, really.  If you've got a torch available, annealing and case hardening are optional extra steps.  The annealing helps keep you from chewing up your cutting tools.  Case hardening will help make the tool last longer.

Carriage bolt with the flange hacked off, and the "lug" filed square(ish)
"lug" notched to make the tool
 Large one for AR-15, small one for .22 Pistol
Tool used for bending feedlips into shape


Apoc Matt said...


Unknown said...

carriage bolts are low carbon or mild steel, neater will heat treat properly, only tool steels high carbon will or work hardened brass will its not needed, cool tool though.

Suburban said...

The carriage bolt seems to work just fine. I went through the process of using Kasenit in an attempt to harden, but I'm not really sure that it matters since this isn't a production tool.