update
in case anyone is still interested...
went to the range today with 4 boxes (100) of #8 1/2 game loads and 2 boxes of rifled slugs. fired all of them, stock closed, stock open, one-handed like a big pistol...without a problem. the only problem i have is that since the gun moves in the grip, the trigger guard chafes on the side of my finger. other than this, no sore shoulder, hands felt fine and this is after 110 rounds. Definitely the best upgrade i can think of for a shotgun.