I know this has had to have been asked before but i have nhmtg and pmags mostly. how long can i store the nhmtg aluminum mags without the feed lips spreading? same question for the pmags. thanks.

Should be able to for YEARS!

Quality aluminum (which definitely includes nhmtg) - good for decades; based on decades of personal experience leaving them stored loaded.

Pmags - can't say.

Hi,

Storing aluminum magazines loaded shouldn't be an issue.  I would download it from capacity by two rounds for reliability though.  

Mags made of Nylon like the P-Mag and Troy have swelled when loaded to capacity for me and others in hot humid conditions. I wouldn't worry about it in Arizona, but it could be an issue in Florida.  Typically the nylon mag swells enough that it will not eject fully loaded.  Police departments that this happened to switch to metal magazines D&H, Browne's, CPD Inc., etc.   Polycarbonate doesn't have this issue so Lancers would be ok.

Thanks:

I would place emphasis on a "QUALITY" aluminum mag. The issue I had in the past (7 years ago) was with a Bushmaster aluminum mag that came with a rifle I had purchased new from a gun shop. I honestly cant say how long it was left loaded but it wasnt more than a year, and the feed lips had separated on it to the point that I couldnt load it to 30 rounds and get it into the magazine well of the rifle. If I loaded it to 28 rounds it would load, but feeding was still an issue.

This was my first rifle... first gun actually, and I never thought to take pictures, but I stayed with pmags. I know they arent bomb proof either. After my experience I would either buy steel or polymer mags. Why not just load one and check it every few months to see if it has issues?

In numerous tests, steel mags don't hold up to torture tests.