Harter66
08-29-2018, 10:13 AM
I've been a party to reloading since the Herters catalog was a staple and Cabela's had 2 stores . I've lived in the golden ....at the trailing edge of the wild cat Glory days . I actually got to shoot a pre-308 Winchester .....well 308 Win .... Dad's 25-06' is one of the very early Rem production rifles and that and Model 12s is where I started .
I started casting in 2007 and moved into cast in rifles in 2010 . I was fortunate to have some truely golden mentors to learn from and to build on .
I had a rifle rebarreled for 7×6.8 SPCII and needed to work up loads . Well there just aren't a lot of commercial 7mm bullets under 120 gr and moulds tend to start there and go up as well . 270 moulds are about as common as 25 yo virgins and they are really all 130s or a variation of . Poor planning on my part . So I chose what seemed to be a flexible powder and checked book data against some old Sierra 120 SP flat base 7mm bullets against the tested data for 120s in the 6.8 . Well that data all worked within the limits of my scales , Chrony and bench . So far good practice whether working up blind for random components or with a change of components . Verify data and work up . If the data agrees then expand to the unknowns with the knowns and be safe ........right ?
Not always . I had a design plan in mind for the rifle . Ms had a deer tag for a NV mule deer and the area was easy living and allowed for plenty of shots typically inside 150 yd .
I started working up a paper patched 27-130 flat point. No problem I had some limited data for 130s and suitable powder , primer , and brass for the test on hand . I had a 3.0 window and worked it in .3 gr steps . The data showed 2450 fps could be reached in a 16" AR carbine so a 21" bolt gun should be a piece of cake ........
That's great except .....
I worked the load up , getting velocities that were just a little slow at the start but with each step closed the gap just a little . 10 loads of 5 each and groups closing and alloy working well I was happy as a pig in mud . Now since I was well within that data I was only passively looking cases and primers and not really feeling the bolt lift , not that it was noticably heavy anyway . Load number 7 broke 2400 fps and shot 1,2" . That was smaller than the 1.75 of load 6 . So I went on and load #7 vented the primer and chronied the same as #6 on the first shot I fired a second because "I knew I was well inside of good data " . It also vented . The LRP pockets were now .25 instead .210 vented . At first glance I blamed the Win LRP primers and the Rem brass . I stopped there and went back to the bench , probably the only smart thing I did .
I weighed the remainder of the brass after I checked the scale for accuracy . The brass was all within a reasonable limit of tolerance . Trim lengths were all good , even on the blown cases , maybe even a little short after the chamber cast was done . In a final fit of head scratching I threw one of the wet wrapped , dried , and slicked up bullets .....
The normal average over is 1-3 gr over for almost all of my moulds notable exceptions are an NOE 225-55 @62 gr , but it came along well after this event , and Lee 452-255 that tip in at 265 gr . Now 10 gr isn't much on a 255 gr bullet that's less than 4% the 7 gr on the 55 is steep but since all 5 cavities throw within .1 gr and there is 62 gr data available it's not a big deal . Back to the bullet on the scale . Remember it was supposed a 130 gr bullet ? Well RCBS is rated on linotype metal and my as hard but more maluable metal was heavier but I would not have expected 142 gr from a 130 gr mould .
Lesson learned , new components or new sources require checking since that learning experience I've found lot to lot jacketed bullets vary by as much as a grain . I did find a box that was 5 gr heavier than another but it was a brand new box compared to a 30 yo box and there were jacket and core alloy changes and they may have run in the same dies , 180 Spitzer boattail the old bullets were 178-9 and the new were 183.1-2 30 cal .
Weigh an unknown bullet , weigh new lots , weigh changes in alloy for those that cast .
I suppose that this goes for every component .
Fortunately neither I nor the rifle was damaged beyond my pride . Fortunately the rifle was built for a much lighter cartridge than it's original however it's design was for a 48-50kpsi cartridge not a 55-58kpsi cartridge and it wasn't intended to shoot a steady diet proof loads which is what it was fed with that work up . Good news , it lived .
I started casting in 2007 and moved into cast in rifles in 2010 . I was fortunate to have some truely golden mentors to learn from and to build on .
I had a rifle rebarreled for 7×6.8 SPCII and needed to work up loads . Well there just aren't a lot of commercial 7mm bullets under 120 gr and moulds tend to start there and go up as well . 270 moulds are about as common as 25 yo virgins and they are really all 130s or a variation of . Poor planning on my part . So I chose what seemed to be a flexible powder and checked book data against some old Sierra 120 SP flat base 7mm bullets against the tested data for 120s in the 6.8 . Well that data all worked within the limits of my scales , Chrony and bench . So far good practice whether working up blind for random components or with a change of components . Verify data and work up . If the data agrees then expand to the unknowns with the knowns and be safe ........right ?
Not always . I had a design plan in mind for the rifle . Ms had a deer tag for a NV mule deer and the area was easy living and allowed for plenty of shots typically inside 150 yd .
I started working up a paper patched 27-130 flat point. No problem I had some limited data for 130s and suitable powder , primer , and brass for the test on hand . I had a 3.0 window and worked it in .3 gr steps . The data showed 2450 fps could be reached in a 16" AR carbine so a 21" bolt gun should be a piece of cake ........
That's great except .....
I worked the load up , getting velocities that were just a little slow at the start but with each step closed the gap just a little . 10 loads of 5 each and groups closing and alloy working well I was happy as a pig in mud . Now since I was well within that data I was only passively looking cases and primers and not really feeling the bolt lift , not that it was noticably heavy anyway . Load number 7 broke 2400 fps and shot 1,2" . That was smaller than the 1.75 of load 6 . So I went on and load #7 vented the primer and chronied the same as #6 on the first shot I fired a second because "I knew I was well inside of good data " . It also vented . The LRP pockets were now .25 instead .210 vented . At first glance I blamed the Win LRP primers and the Rem brass . I stopped there and went back to the bench , probably the only smart thing I did .
I weighed the remainder of the brass after I checked the scale for accuracy . The brass was all within a reasonable limit of tolerance . Trim lengths were all good , even on the blown cases , maybe even a little short after the chamber cast was done . In a final fit of head scratching I threw one of the wet wrapped , dried , and slicked up bullets .....
The normal average over is 1-3 gr over for almost all of my moulds notable exceptions are an NOE 225-55 @62 gr , but it came along well after this event , and Lee 452-255 that tip in at 265 gr . Now 10 gr isn't much on a 255 gr bullet that's less than 4% the 7 gr on the 55 is steep but since all 5 cavities throw within .1 gr and there is 62 gr data available it's not a big deal . Back to the bullet on the scale . Remember it was supposed a 130 gr bullet ? Well RCBS is rated on linotype metal and my as hard but more maluable metal was heavier but I would not have expected 142 gr from a 130 gr mould .
Lesson learned , new components or new sources require checking since that learning experience I've found lot to lot jacketed bullets vary by as much as a grain . I did find a box that was 5 gr heavier than another but it was a brand new box compared to a 30 yo box and there were jacket and core alloy changes and they may have run in the same dies , 180 Spitzer boattail the old bullets were 178-9 and the new were 183.1-2 30 cal .
Weigh an unknown bullet , weigh new lots , weigh changes in alloy for those that cast .
I suppose that this goes for every component .
Fortunately neither I nor the rifle was damaged beyond my pride . Fortunately the rifle was built for a much lighter cartridge than it's original however it's design was for a 48-50kpsi cartridge not a 55-58kpsi cartridge and it wasn't intended to shoot a steady diet proof loads which is what it was fed with that work up . Good news , it lived .