100%
It's test fired at the factory- you get the target. The magwell either holds the mag, and feeds the rounds, or it doesn't- if that's the part that needs to be 'shot', before shipping, I'd say 'OK', as feed issues seem to abound; paying for the mod, magwell, and magazines, should at least come with a level of comfort that the gun will run.
I'd be driving the setup through 75 plus mag changes, on the move, in the rain and mud..(cause god knows, it don't sun, when I want to 'gun'...), and would like to be able to comment on it...this set up is definitely on my 'to have' list, particularly as I can piggy back the mag set up to my XCR 7.62x39 conversion...