joeb33050
02-01-2007, 08:52 AM
We have some data points on the flash hole diameter vs. pressure vs. velocity spectrum.
Bass Ackwards tells of a velocity change with enlarged flash holes.
Mooman 76 did a test with a M93 Mauser in 7MM
Larry Gibson has explained several loads he shoots with enlarged flash holes. (Where is Larry? I keep asking him for permission to use what he wrote, and no response.)
TRK, who is going to scan and send it to me, quotes Phil Sharp about pressure and velocity tests with enlarged flash holes.
I can't measure pressure, don't shoot 30 jacketed bullets a year, shoot low velocity cast bullets. I'm going to make sets of cartridge cases with flash holes enlarged with a #28 drill, and measure velocities with standard vs. drilled flash holes. I invite others to do the same. Maybe we'll get results like Larry's, where accuracy improved and SD went down. ONLY low velocity loads, we don't want a gun blown up here.
Errata: The Fouling Shot, Jan-Feb 2007, "Velocity Check" by Grant Macomber mentions velocity increas from 1300 to 1330 to 1400 fps mean velocity with changes in primer only.
Something's going on here with flash holes and primer choice and primer strike force, and maybe there's an easy and cheap accuracy enhancer hidden in the stories.
joe brennan
Bass Ackwards tells of a velocity change with enlarged flash holes.
Mooman 76 did a test with a M93 Mauser in 7MM
Larry Gibson has explained several loads he shoots with enlarged flash holes. (Where is Larry? I keep asking him for permission to use what he wrote, and no response.)
TRK, who is going to scan and send it to me, quotes Phil Sharp about pressure and velocity tests with enlarged flash holes.
I can't measure pressure, don't shoot 30 jacketed bullets a year, shoot low velocity cast bullets. I'm going to make sets of cartridge cases with flash holes enlarged with a #28 drill, and measure velocities with standard vs. drilled flash holes. I invite others to do the same. Maybe we'll get results like Larry's, where accuracy improved and SD went down. ONLY low velocity loads, we don't want a gun blown up here.
Errata: The Fouling Shot, Jan-Feb 2007, "Velocity Check" by Grant Macomber mentions velocity increas from 1300 to 1330 to 1400 fps mean velocity with changes in primer only.
Something's going on here with flash holes and primer choice and primer strike force, and maybe there's an easy and cheap accuracy enhancer hidden in the stories.
joe brennan