After the good groups I achieve using IMR 7828 ssc with the 140 gr. AB, the 150 gr. CTBST, and the 150 gr. LRAB, I decided to try it with the 140 gr. BT. The target is shown below. I just arbitraily chose the length as about the maximum which will reliably work in the action. The OAL of 3.390" provides about .035" bullet jump.
The second group is with 140 gr. AB. Previously, I had a really great group using the IMR 7828 ssc. This load utilizes once fired NORMA brass vs. NOSLER brass and 1/2 gr. less powder. Again, the OAL was pretty much just a guess trying to get a .060" bullet jump. This group isn't as tight as the earlier test but is stll very promising.
I think both loads would benefit from tweaking the OAL a little.
Three things I find interesting about these (and previous)groups are:
1. The 140 BT are slower than the 140 AB with the same load. I had the same result with the RL22 powder. I don't understand why the 140 BT would be slower than the 140 gr. AB.
2. Loads with the partial full length resized Norma brass are faster than a similar load with Nosler brass. I was thinking the brass might yield similar results. It turns out the partial full length resized Nosler brass yields results more similar to NEW Norma brass but not Partial full length resized Norma brass.
3. The speeds with partial full length resized Norma brass are significantly faster than a similar load with NEW Norma brass. I wasn't expecting than much difference.
The second group is with 140 gr. AB. Previously, I had a really great group using the IMR 7828 ssc. This load utilizes once fired NORMA brass vs. NOSLER brass and 1/2 gr. less powder. Again, the OAL was pretty much just a guess trying to get a .060" bullet jump. This group isn't as tight as the earlier test but is stll very promising.
I think both loads would benefit from tweaking the OAL a little.
Three things I find interesting about these (and previous)groups are:
1. The 140 BT are slower than the 140 AB with the same load. I had the same result with the RL22 powder. I don't understand why the 140 BT would be slower than the 140 gr. AB.
2. Loads with the partial full length resized Norma brass are faster than a similar load with Nosler brass. I was thinking the brass might yield similar results. It turns out the partial full length resized Nosler brass yields results more similar to NEW Norma brass but not Partial full length resized Norma brass.
3. The speeds with partial full length resized Norma brass are significantly faster than a similar load with NEW Norma brass. I wasn't expecting than much difference.