I think there may be something to 5E's statement. If you buy an unfired Repro, or maybe one that's been shot very little, it could simply be a question of "crud" gunking things up. That was clearly the situation with one of mine, which I solved very nicely with an application of Crud Cutter, after which I had no problems. It was not the situation with the other one, however. One was a 12, the other 28, so gauge doesn't seem to matter. But I did have a 20 that caused me no problems, although I did not put nearly as many rounds through it as either the 12 or the 28.
