Today I finally got out to start development in my new 6CM Proof Research barrel for my AI-AT. I was very optimistic after I shot a few strings of factory Berger 109 and Hornady 108 ELDMs. Both of those shot half inch right out of the box.
So I loaded up a string of 5x 3 shot ladders of Superperformance with the 109 Berger LRHT bullets and another 5x ladder of 105 Berger Hybrids with IMR 4451. For both, consulted Hogden’s load site and started on the lower end of the Min/Max range. My goal was to try to match the factory velocities around 2960 ish.
At the start of this test, the barrel probably had a max of 20 rounds and was not cleaned since the factory round test the week prior. I shot another factory 3 shot group of the Berger 109 factory yellow box. They were almost dead on velocity from the previous session, maybe 15 FPS slower than the previous session as it was quite cooler. So I started with the 109s and Superperformance. Brass was virgin Lapua and Fed 205M primers. First string was a huge velocity split. 180 ES and an SD of 92.
The next 2 were slightly better ES in the 80s ans SD’s in the 40s.
#4
The last ladder was a spread of 80.
Accuracy was not terrible, maybe .75” or so. I was seriously thinking my Chargemaster 1500 was F’d. No way could I see these kinds of spreads.
So with dread, I began the next ladder with the 105 Bergers and IMR 4451 thinking either my powder thrower or LabRadar had sh*t the bed. The next five Strings were SD of 19, 14, 8, 3.5 and 5.1.
Any clue what would cause 200 foot spreads like that? All were virgin Lapua, match primers, neck mandreled, etc. WTF?
So I loaded up a string of 5x 3 shot ladders of Superperformance with the 109 Berger LRHT bullets and another 5x ladder of 105 Berger Hybrids with IMR 4451. For both, consulted Hogden’s load site and started on the lower end of the Min/Max range. My goal was to try to match the factory velocities around 2960 ish.
At the start of this test, the barrel probably had a max of 20 rounds and was not cleaned since the factory round test the week prior. I shot another factory 3 shot group of the Berger 109 factory yellow box. They were almost dead on velocity from the previous session, maybe 15 FPS slower than the previous session as it was quite cooler. So I started with the 109s and Superperformance. Brass was virgin Lapua and Fed 205M primers. First string was a huge velocity split. 180 ES and an SD of 92.
The next 2 were slightly better ES in the 80s ans SD’s in the 40s.
#4
The last ladder was a spread of 80.
Accuracy was not terrible, maybe .75” or so. I was seriously thinking my Chargemaster 1500 was F’d. No way could I see these kinds of spreads.
So with dread, I began the next ladder with the 105 Bergers and IMR 4451 thinking either my powder thrower or LabRadar had sh*t the bed. The next five Strings were SD of 19, 14, 8, 3.5 and 5.1.
Any clue what would cause 200 foot spreads like that? All were virgin Lapua, match primers, neck mandreled, etc. WTF?
