Just posted this on Sniper's Hide if anyone is looking for some info. It's on a decent thread concerning 262 Mod 1 Clone.
Any clone is going to be specific to the gun and how 262 Mod 1 performs in that specific gun. That being said...my clone for my precision rifle is...
LC once fired brass 24.5 gr Ramshot Tac 77gr HPBT cannelure (actually pulled from Uncle Sam's 262 Mod 1 rounds -- whole 'nother story there) 2.245 COAL CCI #41s Lee Factory Crimp Brass was trimmed to 1.75 and tweaked (primer pockets uniformed, flash holes deburred and chamfered internally, 20 degree VLD chamfer and deburring) Test group / base line was 10 rounds of factory new 262 Mod 1 through ProChrono Digital (recently calibrated)
My build uses a 20 inch Criterion Hybrid Contour. My average is 2835 fps, but not that it matters...your results may vary.
Average, ES, SD were near identical between the clone and the factory new 262 Mod 1 and my drop tables are dead on between the two. There is that old saying, "Once a bullet leaves the barrel...it doesn't care where it came from." This rifle shoots .9 inch groups at 200 meters.
FYI, I did play around with CCI 450's vs the 41's for this project. The 450's gave me slightly higher pressure / burn / velocity (about 12 fps for exact same load), but...I like the hardness of the 41's. You can tell the difference when you hand prime.