AR Tight magwell question

[Schlyme]

what is the best way to increase the clearance on a tight magwell. And yes, using usgi mags. they are very tight. I started with 400 grit sandpaper and have moved to fine files.

next question, once my mags drop, what can I use to protect the exposed aluminum.

thanks from a tinkerer

[DEF23]

Actually, the aluminum will oxides itself and then you won't need any outer coating........LOL !!!

Or some aluma-hide from Brownells would work.

[Whiterabbit]

you got it backwards. Start with files, then move to sandpaper. Files till it fits, then make it pretty with the paper. I like wetsandpaper best.

and for THIS purpose, I would use bichwood casey aluminum black to patch the cut areas.

[VictorFranko]

OP, was this an 80% lower?
I had to mill 0.030 out of a crappy 80% lower to bring it into print.

[emy]

How many mags do you have ? are all of them tight, Like Mr VF said if it's an 80% you might have to do alot of filing.

[Schlyme]

I tried at least 3 (all USGI aluminum) of the mags I have. One is still pretty tight, the other 2 are just snug. I'll try all of them to see if any will drop. supplies for coverup will have to wait till after all other holiday stuff is done.

thanks

[DEF23]

Birchwwod casey aluminum black will wear off after just a few uses with tight mags. Better to use something that has better wear value in the long term.

OP --- something to think about with your magwell. If it won't even fit USGI mags........How's it going to fit all of the rest of them too ??.......Or drop free, as intended ??

Many of the newer generation of polymer magazine are sometimes larger than normal size. And even Magpul (who is usually good) has made at least two runs that were on the large size.......

Just keep it going, real slow, a little at a time --- using a small diamond file first (clean out often), then using sandpaper on a ruler to finish it up.

Hope this helps you out some, sir.

[Schlyme]

One more question, what can I use to determine the tight spots? I've been looking though the mag well with light behind. I was thinking putting some baby powder to help make sure I'm working the right spot

[Cheep]

Use a sharpie to make the whole mag well black, slide in your tightest mag a few times and look for where the black is worn off-that will be the tight spots.

[kcstott]

if you have it on hand a acetylene torch. Use just the acetylene and soot up the lower. It is a bit messy but the thing is with the soot it's very sensitive to touch. it will show spots that a sharpie won't.

But everyone has a sharpie laying around somewhere.