New to me with PC

[gpidaho]

Well guys, I thought I'd seen most that could go wrong when PCing but had a new one on me today. I was coating some gas checked 8X57s (the Lee 175s) and it was a real female dog getting the checks on them. After expanding the checks they were seated through a Lee push through. I coated the boolits electrostaticly and popped them in a 400 degree oven. 5-6 mins. into the bake they started going off like popcorn jumping out of their checks. What the **** The 8X57s were checked with Hornady copper checks. None of my boolits (30 cal.) wearing my homemade aluminum checks jumped or even moved on the boolit. I could see this happening if I'd have cleaned them with a volatile liquid, but these wear just plain recently cast boolits uncleaned. Anybody else ever seen this happen? Gp

[popper]

Were the H GCs annealed? How did you expand them? Pits in the base? I started annealing GC with a torch and noticed it almost looked like the GC were lubed with something that 'burned' off. Even moisture trapped will pop them off. Doesn't take much & yes, I've had GC pop off when cooking. Annealed, they seem to seat & crimp better with the Lee PT.

[gpidaho]

Thanks for your thoughts popper. No, the checks weren't annealed but after your comment I'll try that first. I expanded the checks with a tool made from the shank of an appropriate size bolt as posted by Ben. I will heat the next batch with a heat gun to make sure there's no moisture but it's very arid here in southern Idaho so I doubt that's it. Thanks again for your post, I knew one of you guys must have had this happen. Gp

[Walter Laich]

another way to go is using a propane torch.

[bangerjim]

Of them many MANY GC's I have put on and then PC'd, I have never had a single one pop off like you are describing. That includes 223/30/357/44/45.

Must be ghosts?

[gpidaho]

Jim, I do at times feel a presence! lol Yup, a first for me too. Enjoy the evening all. Gp

[Moonie]

I had some 30 and 270 caliber ones pop off when I had cleaned already checked boolits with acetone. Even after letting them dry for 24 hours apparently there was enough left under the checks to pop them off.