Let's see if I have learned how to post pics...

The mag on the left, with bullets inserted, is the mag that came with my Colt 6731. It's a 10-shot (or is it 9?) with some sort of black plastic deal on the bottom, stamped Colt on the bottom.
The mag on the right is a no name mag with nothing stamped anywhere.
I have zero problems with the Colt 10 rnd mag.
The last time I tried to shoot with the mag on the right, (either it or its brother Mag #2) it failed to fire every third shot or so.
But when I tried to manually cycle it by loading 5 rnds at a time, the failure rate decreased and it took 3 cycles before the rifle did this:

When I was firing (instead of manually cycling) the bolt might not travel even that far.

I assume the prob;lem is my no-name mags. Yeah I bought them before I read the FAQ. My bad.
My question is, in the picture on top, the ways the lips are configured looks different. The no name mag has metal in places the Colt doesn't, and there's a bend at the front that the no-name doesn't have.
I was thinking that with the judicious application of some tool, maybe even a file, I could try to shape it more like the Colt.

OR should I just fill them with concrete or epoxy and use them for rifle holders?

It looks as if the problem mag is a USGI mag so it should be made to mil-spec. A side picture would give a definitive answer.  

The mag should be aluminum, but if it is steel, it is probably a British or Singapore mag and they have been known to need a little work. This could be anything from filing the mag catch hole it get the mag to sit lower in the receiver, to bending the feedlips a little.

Before I would dremel anything, I would try a new spring and one of the Magpul Anti-Tilt followers and see if that cures it.

Or if you've got more time than money it might be worthwhile to have at it with a dremel...

GI mags are $11-$15...just buy something that you know will work, it's NOT worth the headache.

With mags at $10 NIW, why bother??

Another way to ask the question might be...Is the missing metal the main difference? BC if it is, then I have a real clue when I'm looking at those $11 mags as to what I'm getting. (I've since learned to stay away from the ones with no markings on the butt at all.)

Check the EE, I just got 5 NIW USGI 30 Rd mags for $50 Shipped.  So long as you buy from folks w/good feedback, the EE has great deals.  Just stick with USGI mags.

USGI mags will have makers such as Center, Sanchez, OKay, Colt, FN, etc.........

Seems like the consensus is.. why bother?
Although this reminds me vaguely of Dr. Suess, and I'd still like to know the deal with the missing metal,
It's goodbye to Mag One and Mag Two.

Just pony up for new mags... not worth the headache whatsoever.... especially if the mags in question will forever be questionable


- BG

If you like projects go ahead and do it, sometimes it's fun just to fix something if time and money are not an issue of course. Otherwise just buy a new mag.

Crush it and buy a new magazine.

Shoot it and Post Pics! And buy new mags.

Before I knew better, I bought 2 USA mags. They didn't work worth a sh$t! I threw them away and got USGI mags.

Problem solved!