Recently had the financial opportunity to get dies and bullets for this, had everything else lined up. This Gen 3 20sf has a KKM 6" barrel, the Wolf 22lb non captive return spring with the steel guide rod and a q tip/Mothers polish on the trigger linkage. With fresh Starline brass, WLP primers, Longshot, and 180 gn FMJ from Everglades, I laddered by .1 gn from 8.5 to 9.5 (3 of each) across the chrono. Last Sunday up in the NW corner of SD was clear, calm and almost 60. Used a Caldwell rifle rest as a platform.
8.7 1298 1278 1269 9.2 1330 1346 1332
8.8 1289 1294 1305 9.3 1350 1317 1341
8.9 1302 1298 1287 9.4 1346 1345 1342
9.0 1325 1345 1328 9.5 1361 1350 1373
9.1 1333 1305 1312
After finding the sharpy-marked brass, no expanded primers and with calipers the 9.0+ grain loads were at .429. Interestingly, after I popped out the primers and measuring, the higher loads shortened the brass by up to .010. Haven't resized them yet to see if that length gets restored. Maybe the .004 above the original .425 is coming off the top. I seat and crimp in two steps with the "bell removal" set at .421-.422., OAL at 1.257-1.260.
I posted an intro last night, been reading here for a while. Lots of great info. Plan on putting some more brass into low earth orbit.
Thanks jgy, some great info
Ken
Quote from: jgy on December 12 2020 10:42:00 PM MST
Recently had the financial opportunity to get dies and bullets for this, had everything else lined up. This Gen 3 20sf has a KKM 6" barrel, the Wolf 22lb non captive return spring with the steel guide rod and a q tip/Mothers polish on the trigger linkage. With fresh Starline brass, WLP primers, Longshot, and 180 gn FMJ from Everglades, I laddered by .1 gn from 8.5 to 9.5 (3 of each) across the chrono. Last Sunday up in the NW corner of SD was clear, calm and almost 60. Used a Caldwell rifle rest as a platform.
8.7 1298 1278 1269 9.2 1330 1346 1332
8.8 1289 1294 1305 9.3 1350 1317 1341
8.9 1302 1298 1287 9.4 1346 1345 1342
9.0 1325 1345 1328 9.5 1361 1350 1373
9.1 1333 1305 1312
After finding the sharpy-marked brass, no expanded primers and with calipers the 9.0+ grain loads were at .429. Interestingly, after I popped out the primers and measuring, the higher loads shortened the brass by up to .010. Haven't resized them yet to see if that length gets restored. Maybe the .004 above the original .425 is coming off the top. I seat and crimp in two steps with the "bell removal" set at .421-.422., OAL at 1.257-1.260.
I posted an intro last night, been reading here for a while. Lots of great info. Plan on putting some more brass into low earth orbit.
jgy what chronograph did you test the velocities with?
A ProChrono Digital that I've used now for over 7 years. It was around 6 feet away from the barrel. I spent a bit of time searching for an identical scenario as mine to see if these were 'ballpark' figures but didn't find a perfect fit. Also the second shot of the 9.3 group produced a failure to feed, no problems before or after that. Was able to resize the brass this afternoon and it lengthened out .004, some .005. Hoping to not have to mess with crimp die.
Thanks for the reply, the 6" barrels do add to the velocities quite well