sportsman223
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25 ACP Construction..
Drill Bit sizes…
Here are the Letter Gauge drill bit sizes
H 0.266 in
I 0.272 in
J 0.277 in
NOTE:
SAAMI specs for the outside dimension of a .25 ACP case is 0.278.
J size bits are 0.277
K size bits are 0.281
L size bits are 0.290
I've found the L bits work well, but you could try a K and see how it works for you. If your cases are too tight you can always enlarge the hole with an L.
If you have a drill press and calipers the L bit is all you need. Just put a 209 primer in your breech plug and measure the overall length. Then start drilling very slowly, inserting the ACP case into the drilled hole frequently untill it's a thousand's or two less than the measurement with the 209. Then try it in your gun for a "slam fit". If it's too tight you can always drill a tad deeper.
I'm coming up w/a 1.327" OAL using a W209 primmer. The primmer measure's .300"OAL. I know this is the longest primmer available on the market, at least to my knowledge. Mic shows .222" OAL from the primmer head to the bottom of the primmer.
