I'M looking for anyone that has loading experience cloning the MK262 round the military uses from black hills.
Here is what i have worked up so far and just trying to find more data, does anyone have any other load data to add?
I have had good results using IMR 8208 XBR powder, my results are an average 2,665 FPS with a standard deviation of 16.88 out of an 18" SPR wilson combat barrel 1:7 twist using 23.1 grains, LC brass, and CCI#41 primers. Seating is at 1.869" to ogive using 77 grain SMK w/cannelure. Chronograph placed @ 5'. shots taken in 68-91 degree temps.
This powder is a short extruded type, also the factory new Black Hills (red box)69 grain OTM is short extruded powder coming in at 24.2 grains, 2012 WCC headstamp.
CFE223, and varget don't even come close to the velocity i was looking for to match the MK262 without a compressed charge, Tac powder works well but changed with temprature, IMR 8208 xbr is not near as sensitive to temp changes like the other above mentioned that i have used.
My groups are consistently under 5/8"@ 100 yards.
P.S. If you attempt loading per my data, do so at your own risk. 23.2 is the max recommended charge for 8208 xbr@55,000 psi.
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