I bought two pro mags for my bone-stock Mini 14 the 5.56 model. quality fit and finish seem excellent. To be perfectly honest at the range i did have a jam, once. (Be advised my brand new glock 26 did the same thing after about 200 rounds - stovepipe failure to feed - so maybe there's almost no gun that's totally immune to jamming?).
Failure to feed, round stuck with chamber midway open. I put 100 rounds through it that day. I don't know it the mag was a fault. This happened after about 50 rounds, the gun was hot and of course a little bit dirty. I finished off the rest of my ammo and it did not jam again. I always clean the heck outa my guns before and after shooting, so the jam(s) may have been caused by over-lubrication.
The jam on the mini happened about round #5 through the mag so it may well have been the gun and not the mag: i bought it used for $600 showed light wear, but who knows that sort of care it had or what parts like springs got replaced by the former owner, if any.
