I took my Mini-14 in for some work and when I got there my gunsmith was putting one of those stock rigs with the adjustable AR style butt stock on a buddy of mine's sks and I asked her about them and addressed the issue of them failing and she said that once you set it you could prettywell count on themif you get a good one. It makes sense, if they're designed to fit a certain firearm one would like to think they would be able to hold up to it.