I've used mine a lot. I have heard about hard kicking rifles cracking stocks when the shooter tries to completely eliminate recoil with four 25 lb shot bags. The result is "no give" - and so - "something gives" - the stock.
One friend, with far more experience with "big-boomers" than I do has said he's never had a problem - but he admits to tucking a piece of foam into the stock holding part. He also stressed that he never tried to eliminate recoil - only reduce it - and thus, never used more than a single bag of shot.
His advice seems pretty to good, to me anyways.
