I said i would post my findings on shooting the GS Custom 414gn bullet. I worked up loads starting at 100yds, I settled on 148gns of US869, this is a nice firm load.
The test rifle was my 375 Snipetac with a Bartlien Gain twist barrel. 16 to 8" exit twist at 31" It was just under 8" at 32", i cut off 1 extra inch to bring it closer to 8" exit.
It sports a Viersco custom repeater action, Manners carbon stock and a Night Force 8-32x56 scope. Rifle is under 17 pounds. Let me tell you shooting 414gn bullets at 3000 fps is a hand full.
100yd tests started with trying several types of powder,
US 869 and H-BMG50 The latter did not group as well.
Top 2 shot group was the BMG-50 powder
Lower group was the US 869, both were with 148gns. The US 869 showed a higher velocity potencial. This target was shot on day one of testing. Temps were around 90deg.
The next day I set up the 535yd target, I plugged the numbers into Exbal and it gave me 8.5moa from 100yd sight in, also -1.5 moa for wind correction. I fired two shots with the BMG50 loads, group was not good. I then fired 2 shots with the US869 load and the group was right at 1.629". The day started with moderate gusting winds and they kept increasing so I decided not to try and set up the 1150yd target until the wind was more managable. I did not set up the chrono as the wind will blow it over.
I tested my pet load using the 350gn Predator solids vs the 414 GS Customs.
Fourth of July brought nice weather as a storm front went through over night. The wind was 2-6 mph from the left, 76deg but quite humid. I set up the 1150yd target, went back to the work shop and loaded up 5 test rounds. I consulted Exbal once again, it showed I would need 24.8 moa from the 100yd starting point, Since the rifle was also sighted in at 535yds i also checked exbal to see what the setting would be from that range, 16 moa needed. I made the nesesary adjustments to my scope, plus the - 1.00 moa for wind. I fired two shots and made my trek out to the target. Two shots had landed on the board, low aprox 2" apart. I measured 32" low from sight center and 10" right. I went back and checked the scope settings and found that I did not count correctly when comming up. I made the adjustments with elevation and windage, fired two more shots and went back out to check. The group now was on target center with just a little left. This group measured 1.750" center to center, just about the same as the first two shots. All of the bullet holes are perfectly round. Velocity was lower today vs the first day tests. First day it was running 3075fps but it was much drier air and hot, today was cooler and very humid. Exbal was off by aprox .4 moa on its predictions, I used 1.250 BC, 1400 elevation here.
I didnt set up the chrono on day two of testing, just one and three, the difference in velocitys was prolly due to hot vs mild weather. I used the same loads for all tests. I used the same cases for each test session.
My next test will be with a standard 8 twist Lawton barrel and throated for these bullets.
So far I am very pleased with the test results.
Dave
The test rifle was my 375 Snipetac with a Bartlien Gain twist barrel. 16 to 8" exit twist at 31" It was just under 8" at 32", i cut off 1 extra inch to bring it closer to 8" exit.
It sports a Viersco custom repeater action, Manners carbon stock and a Night Force 8-32x56 scope. Rifle is under 17 pounds. Let me tell you shooting 414gn bullets at 3000 fps is a hand full.
100yd tests started with trying several types of powder,
US 869 and H-BMG50 The latter did not group as well.
Top 2 shot group was the BMG-50 powder
Lower group was the US 869, both were with 148gns. The US 869 showed a higher velocity potencial. This target was shot on day one of testing. Temps were around 90deg.
The next day I set up the 535yd target, I plugged the numbers into Exbal and it gave me 8.5moa from 100yd sight in, also -1.5 moa for wind correction. I fired two shots with the BMG50 loads, group was not good. I then fired 2 shots with the US869 load and the group was right at 1.629". The day started with moderate gusting winds and they kept increasing so I decided not to try and set up the 1150yd target until the wind was more managable. I did not set up the chrono as the wind will blow it over.
I tested my pet load using the 350gn Predator solids vs the 414 GS Customs.
Fourth of July brought nice weather as a storm front went through over night. The wind was 2-6 mph from the left, 76deg but quite humid. I set up the 1150yd target, went back to the work shop and loaded up 5 test rounds. I consulted Exbal once again, it showed I would need 24.8 moa from the 100yd starting point, Since the rifle was also sighted in at 535yds i also checked exbal to see what the setting would be from that range, 16 moa needed. I made the nesesary adjustments to my scope, plus the - 1.00 moa for wind. I fired two shots and made my trek out to the target. Two shots had landed on the board, low aprox 2" apart. I measured 32" low from sight center and 10" right. I went back and checked the scope settings and found that I did not count correctly when comming up. I made the adjustments with elevation and windage, fired two more shots and went back out to check. The group now was on target center with just a little left. This group measured 1.750" center to center, just about the same as the first two shots. All of the bullet holes are perfectly round. Velocity was lower today vs the first day tests. First day it was running 3075fps but it was much drier air and hot, today was cooler and very humid. Exbal was off by aprox .4 moa on its predictions, I used 1.250 BC, 1400 elevation here.
I didnt set up the chrono on day two of testing, just one and three, the difference in velocitys was prolly due to hot vs mild weather. I used the same loads for all tests. I used the same cases for each test session.
My next test will be with a standard 8 twist Lawton barrel and throated for these bullets.
So far I am very pleased with the test results.
Dave
