I was at my brother in law's last week end and we went to the gun club and emptied a few Winchester high brass 1-1/4 oz field loads and after looking at Hogdon's site selected Rem. Fig. 8 wads to go with his Universal clays powder and 1-1/8 oz shot he had already bought. Everything appeared to go together alright but after an hour or so a large percentage of the shells had the crimps pushed open and the shot was falling out. Thinking perhaps he hadn't seated the wad well enough we opened them up, dump the shot back in the loader and seated the wads firmly. Same results. I researched a little more and found a load calling for WAA12 wads so we got some of those and the crimp appears much flatter and to my knowledge hasn't tried to open up.

My question is; Has this happened to anyone else?

Does the fact that these are gun club replicas of the Rem. Fig 8 come into play?

Not that unusual. Just because a load is published dosn't mean it always fits well. Second the Winchester hull used is not the best. Most Win hulls these days are of thin plastic and resemble the Win Universal which is junk and reloads poorly, only the AAHS hull is worth reloading IMO. Getting a good crimp on the thin "Universal" type hull is very difficult; they also crush easily too. The new two piece Win hulls have less volume than the old one piece CFAA of years past. If you must load the Win hull the Downrange DRA-12 wad offers a bit more room allowing for better crimps. When it comes to hulls in 12 & 20 ga I use the Rem 1 piece hull; STS, Nitro 27, Gun Club, Sure Shot, Sport Load etc they are far better to work with.

Solved the problem by switching to the load I use Red Dot powder and WAA12SL Wads with 1 oz shot.