I may not have stated this earlier, but I have Unique, Red Dot, Blue Dot. Green Dot, Universal, AA1680, Longshot, and BE-86 covering Boolits PC'ed with Smoke's Black PC.
The Unique, Red Dot, Blue Dot. Green Dot, Universal and AA1680 have been "soaking" for 6 month or longer and seem to have no interaction with the PC.
A qualifying note is required. The Dot and Unique powders were all manufactured in the early 90's. What can I say, my Dad and I shot shotguns then and stocked up. I've got 4 pound cans of all these that were under $40.00. The universal is at least 15 years old. The AA1680 is two years old.
The Longshot is six months old and it is reacting pretty aggressively. Sticking to the PC and eating the outer layer off so the shine to the powder is completely gone. Probably half to three quarters of the boolit has powder flakes stuck to it. The exposed PC is very dull.
The BE-86 was bought last Friday and is reacting more than I had imagined. The powder is caking on layer after layer. This did not happen with the Longshot.
I was trying to find a powder for high end 10MM loads with PC'ed boolits.
My concern is not only the degradation of the powder, but also the effects to the PC., (Softening?). I do know the powder will only be in contact with the base of the boolit, but I don't want to be smearing PC coating down the bore of my guns and then ironing in with subsequent shots while putting more layers down the bore. Sorta like leading squared.
This a picture of a boolit after only two days in the BE-86. As you can see, in some places, the powder is multiple layers deep. These kernels are stuck and none fell of when I picked this boolit up with needle nose pliers to take the pic.
A gas check would probably solve this, but my bullets are all plain base.
I do have a check maker for aluminum checks, plain base in .357 and suppose I could buy one for the 40 Cal bullets to keep the powder off the bases.
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