A follow up to the process of converting centerfire cases to rimfire. When making the new offset rimfire primer pocket, the hole is finished with a .224" diameter reamer. This gives the .225"- .226" diameter acorn blanks a press fit. This is good to minimize gas leakage when firing. Sometimes the acorns can be thumb pressed into place, other times it takes a bit more pressure to seat them.
After chewing on it a while, I came up with a way to seat the acorns in the loading press. First I rummaged through my dies to find one that the .44 long rimfire case would slip easily into, yet the rim would seat against the bottom. It turns our that a .45acp sizing die was perfect.
Next a flat topped ram was needed to press the acorn into the pocket, flush with the back of the case. Basically a replacement shellholder, but with a smooth flat top. The critical measurements were taken off an RCBS shellholder. Then over to the lathe to turn it out.
I just primed 20 cases and it worked great.