I was doing some load development for .308 and my rig which is a GAP 308 with 26" Bartlein barrel. These were loaded with once fired brass, Win Large Rifle Primers, 175gr SMK, and Varget all loaded to 2.810".
42.5gr= 2599, 2578,2569,2583,2580 avg=2581 ft/sec
43.0= 2640, 2635, 2609, 2645,2647 avg=2635 ft/sec
43.5= 2661, 2645,2635,2640,2656 avg=2647 ft/sec
44.0gr= 2661,2677,2666,2656,2661 avg=2662 ft/sec
Factory Hunting Shack 175=2640,2683,2666,2646,2644 avg=2655ft/sec
There were no pressure signs at all in any of the loads and no sticky bolts. These were all shot for accuracy and all were 1/2MOA or better at 100yards. The 42.5 & 43.5gr groups were the tightest group close to a 1/4MOA.
From 42.5 to 43.0gr there was a ~50ft/sec increase in velocity but every other 0.5gr increment resulted in only 15-20ft/sec increase. When looking at the averages you can definitely see an increase, but looking at the individual numbers from the last three batches you can barely tell that there is a full grain difference in powder.
The powders were measured with Hornady's dispenser/scale down to the 0.1grain for every load. The chrono was functioning fine since previous chronos of the HSM showed pretty much identical numbers. Just wanted your inputs to verify that those small increases are normal as you get towards max load.
42.5gr= 2599, 2578,2569,2583,2580 avg=2581 ft/sec
43.0= 2640, 2635, 2609, 2645,2647 avg=2635 ft/sec
43.5= 2661, 2645,2635,2640,2656 avg=2647 ft/sec
44.0gr= 2661,2677,2666,2656,2661 avg=2662 ft/sec
Factory Hunting Shack 175=2640,2683,2666,2646,2644 avg=2655ft/sec
There were no pressure signs at all in any of the loads and no sticky bolts. These were all shot for accuracy and all were 1/2MOA or better at 100yards. The 42.5 & 43.5gr groups were the tightest group close to a 1/4MOA.
From 42.5 to 43.0gr there was a ~50ft/sec increase in velocity but every other 0.5gr increment resulted in only 15-20ft/sec increase. When looking at the averages you can definitely see an increase, but looking at the individual numbers from the last three batches you can barely tell that there is a full grain difference in powder.
The powders were measured with Hornady's dispenser/scale down to the 0.1grain for every load. The chrono was functioning fine since previous chronos of the HSM showed pretty much identical numbers. Just wanted your inputs to verify that those small increases are normal as you get towards max load.
