It happens once in a while with every shell. I have had it happen with Gold Medals, the old AA's, Remington STS, Nitro's and Clubs. It shouldn't happen often and sometimes they are new, sometimes they have been reloaded several times. I use a Spolar hydraulic, but it has happened with my MEC's and with my PW's. Just pay attention and don't worry about it.
I have had this happen once on my PW 800 plus. The head came off in the deprime/prime station and the case stuck on the primer knockout punch when I raised the handle. I have had periodic trouble with primers seating correctly at this station on Gun Club emptys and am beginning to think it is something to do with the bond between the unibody being unsymetrical with the steel head so the primer pocket is not in true alighnment with the seating punch. The primer will start in but not seat to correct full depth and the press has so much leverage it will push up the case head ruining that case and primer. It happens about 5 times in maybe 200 loads and always on once fired emptys. I have learned to accept about a 2% or less failure rate in getting good loads on any progressive. Have a great day! Lee.
Have had that happen with paper hulls in my Pacific (Hornady) but not with any plastics, a buddy has had several AAs (new style) pull off like that in his SBT Parazzi,(sp?) but he can look down the bbl after each shot. Ross
Well, I have never had a Gunclub, Nitro, STS, or AA pull from the base. We discussed this today at the gun club. No one else has had this problem either (we are talking about 7 guys who reload 15K rounds each per year).
One member posited this... Perhaps if a gun's chamber is slightly oversized, then the brass or metal base can over expand, leading to the separation. Those of you who are having this separation may want to check that. If the brass / metal base after firing is standing proud of the plastic hull, this could be a tell-tale sign.
Another possibility is that the resizing station is perhaps not doing a good job? Like on the previous reload prior to the failure?