I have a couple questions for experienced M82 owners.  First, do any of you keep your mags loaded for extended periods of time, in other words store them loaded?   I'm curious because Barret advises to NOT keep mags loaded for long duration.  Second does anyone use M107 mags in their M82A1?  They are supposed to be interchangeable but at $170 a pop I would want to be sure they are just as reliable in the M82.  The only real advantage is the witness holes to visually check round count and the fact that you can get the M107 mags in FDE which I think would look cool in a black M82.

I don't store mine loaded, I load as many as I plan to shoot in a magazine or 2 the day of. I wouldn't bother with m107 mags if you can get the m82a1 cheaper. I got most of mine off eBay back in the day.

I keep mine loaded, no probs but haven't shot them much

Find out if replacement springs are available and test one to failure.

It's not a big deal either way, I just was thinking maybe there is some reason that Barrett would state they should be kept unloaded, like maybe the weight of the rounds putting a lot of stress on the springs if stored that way.  

We used to keep 82A1 mags loaded in the vault for a really long time. There were a few in there loaded for about 2 years. We took them out and fired them. Worked great.
Not sure who put that out at Barrett. There has been such a huge turn around since I left.

I keep mine loaded with 9 rounds, and have no worries about the springs.