Ladder Testing .308 99f
Posted: 17 Jul 2019 12:35
Reporting on this here rather than Rifle Reloading Section.
Conducted this test today with interesting results if somewhat confusing. Rifle is a 1964 dated Savage 99f. Test loads were all IMR4064 starting at 40.0 and going to 42.5 in .5 grain increments. Winchester FL sized and trimmed brass from the same lot 3x fired. Bullet was the Hornady 168 Grain HPBT "Match". No crimp used. OAL (2.2866)was set to allow a .010 jump to the lands. This is well beyond magazine length. I loaded 24 with CCI200 and 24 with CCI250 (Magnum) primers. Overcast morning, about 15 Celsius and dead calm. Chronograph was working perfectly. All shooting done at 50 meters. I stopped between strings to let barrel cool a bit.
I started by dialing in scope from POA to POI using rounds made from same brass lot and bullets but with 43.5 grains of Varget and a magazine length of 2.819". It took a couple of shots to warm up the barrel and then get the scope adjusted. This worked about as expected for this rifle with the final three shot group at about 2MOA. I then started the tests and the first 4 shots (CCI 250 40.0 grains) strung vertically about an inch apart and I suspected something had loosened but on checking nothing was found amiss. I then fired the next 4 and this set the pattern for the remainder of the testing, a group of 3 shots and one outside the group. Here are two examples. It didn't matter which primer was involved they all more or less shot the same with slight differences in group size, centre and shot dispersion.
I was checking every case for pressure signs when I noticed the telltale shiny ring on some of the cases. Then it happened. First shot of the second to last string of the CCI200 loads. That was the end of the testing. All that brass lot is going to scrap. Just to be sure the rifle is going to the GS for headspace check.
I will report the velocities etc in the next post.
Conducted this test today with interesting results if somewhat confusing. Rifle is a 1964 dated Savage 99f. Test loads were all IMR4064 starting at 40.0 and going to 42.5 in .5 grain increments. Winchester FL sized and trimmed brass from the same lot 3x fired. Bullet was the Hornady 168 Grain HPBT "Match". No crimp used. OAL (2.2866)was set to allow a .010 jump to the lands. This is well beyond magazine length. I loaded 24 with CCI200 and 24 with CCI250 (Magnum) primers. Overcast morning, about 15 Celsius and dead calm. Chronograph was working perfectly. All shooting done at 50 meters. I stopped between strings to let barrel cool a bit.
I started by dialing in scope from POA to POI using rounds made from same brass lot and bullets but with 43.5 grains of Varget and a magazine length of 2.819". It took a couple of shots to warm up the barrel and then get the scope adjusted. This worked about as expected for this rifle with the final three shot group at about 2MOA. I then started the tests and the first 4 shots (CCI 250 40.0 grains) strung vertically about an inch apart and I suspected something had loosened but on checking nothing was found amiss. I then fired the next 4 and this set the pattern for the remainder of the testing, a group of 3 shots and one outside the group. Here are two examples. It didn't matter which primer was involved they all more or less shot the same with slight differences in group size, centre and shot dispersion.
I was checking every case for pressure signs when I noticed the telltale shiny ring on some of the cases. Then it happened. First shot of the second to last string of the CCI200 loads. That was the end of the testing. All that brass lot is going to scrap. Just to be sure the rifle is going to the GS for headspace check.
I will report the velocities etc in the next post.