[ThatBeardedGuy]

Well, yeah, if you've got the money to burn, pick up some extra parts, but you can't put a number on when a piece of a weapon will suffer a catastrophic failure if it's faulty. It'll just break. Like I've said elsewhere, I've seen a perfectly good Colt M4 explode (probably a squib load), but unless you're buying extremely cheap components, you're going to be fine. As with everything, you get what you pay for with firearms. Since you bought a Sig, I suspect you're not buying cheap components.