CAS TOPICS > The Darksider's Den

How I convert centerfire brass to rimfire

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ndnchf:
There has been a lot of interest in the rimfire cases that I make from centerfire brass. Since I'm in the process of making 10 more .44 long rimfire, I made a two part video on the process I've come up with. Maybe this will inspire you to makes some of your own :-)

ndnchf:
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.

ndnchf:
I made a couple more tools to make reloading these rimfires a little easier. First is a decapping stand and custom punch to knock out the fired acorn blank primers.

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ndnchf:
I've made a few reloadable .56-50 rimfire cases as well as a bunch of 44 long rimfires. The most tedious part of the process is measuring and marking exactly where to drill the pilot hole for the new offset chamber.  I'm using a caliper and magnifier on my glasses to see and mark each one. Inevitably there is still some variation.  I want to make more .56-50,  so this past week I've been trying to think of a better way. Here is what I came up with.

I made a jig that has nub precisely machined to fit in the centerfire primer pocket. The jig OD is the exact same diameter as the case rim - .650". Using the edge, I measured in and marked the spot on the jig where I want the pilot hole. Then a 3/32" hole was carefully drilled through the jig. To use it, the jig's nub is placed in the centerfire primer pocket, then a 3/32" transfer punch is placed in the hole and tapped with a hammer. This puts a dimple at the same spot on every case where the pilot hole needs to be drilled. I made one .56-50 tonight with it and it worked well.  But rather than cut up my precious stash of .50-70 to make more, I just ordered 50 Starline .56-50 cases from TOTW. 

I think this will make the process go easier.

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