PWS
03-09-2011, 01:08 AM
I ran out of gaschecks earlier this winter and being short on money and long on time decided to keep playing around with loads.
Test rifle is an off-the-shelf Ruger S/Lam in .30-06 and the mold is a stock Lyman #31141 date stamped 05-08 that casts in Linotype at ~ .310-311" (certainly not a "perfect" mold). Loaded to 3.060" oal over 10gr Unique, fired by CCI300s (ran out of LR's too...) and tested at 50yds.
This is the braggin' group of the three. Next was 1/2" and last was 1 3/8". No big deal you say but everything the same but with a 200gr LBT cut for the rifle cast in Linotype, treated the same way and the WORST group of ten at 50 has been just under 1/2". The LBT just starts to lead foul (1250fps mv) as does the Lyman (1350fps mv). The most intriguing part is that bullets fully lubricated shoot into 1 - 1 1/2" at 50. After reading a few threads about "overlube" or "lubepurge", I lubed up some bullets so that the gas check shank was the only place with lube and.... :holysheep
What a difference in accuracy!
http://castboolits.gunloads.com/imagehosting/166284d77045c38c5a.jpg
I recovered one of the Lymans from the snow downrange and hmmmm.... One side is pristine except for the rifling, the other shows... gas erosion? It can't be friction erosion as the shank isn't touching the bore. Why did the gas erode the side of a bullet when it didn't erode the base?
http://castboolits.gunloads.com/imagehosting/166284d77045c4a97d.jpg
http://castboolits.gunloads.com/imagehosting/166284d77045c5af31.jpg
I'm guessing that 10gr is just a skosh too much with the Lyman and right at that point with the LBT. The LBT maintains the same level of accuracy but the Lyman dropped off. I'm going to try some 9gr loads next. Both bullets have approached 1MOA with various loads with gaschecks but neither have ever shot this well!
Test rifle is an off-the-shelf Ruger S/Lam in .30-06 and the mold is a stock Lyman #31141 date stamped 05-08 that casts in Linotype at ~ .310-311" (certainly not a "perfect" mold). Loaded to 3.060" oal over 10gr Unique, fired by CCI300s (ran out of LR's too...) and tested at 50yds.
This is the braggin' group of the three. Next was 1/2" and last was 1 3/8". No big deal you say but everything the same but with a 200gr LBT cut for the rifle cast in Linotype, treated the same way and the WORST group of ten at 50 has been just under 1/2". The LBT just starts to lead foul (1250fps mv) as does the Lyman (1350fps mv). The most intriguing part is that bullets fully lubricated shoot into 1 - 1 1/2" at 50. After reading a few threads about "overlube" or "lubepurge", I lubed up some bullets so that the gas check shank was the only place with lube and.... :holysheep
What a difference in accuracy!
http://castboolits.gunloads.com/imagehosting/166284d77045c38c5a.jpg
I recovered one of the Lymans from the snow downrange and hmmmm.... One side is pristine except for the rifling, the other shows... gas erosion? It can't be friction erosion as the shank isn't touching the bore. Why did the gas erode the side of a bullet when it didn't erode the base?
http://castboolits.gunloads.com/imagehosting/166284d77045c4a97d.jpg
http://castboolits.gunloads.com/imagehosting/166284d77045c5af31.jpg
I'm guessing that 10gr is just a skosh too much with the Lyman and right at that point with the LBT. The LBT maintains the same level of accuracy but the Lyman dropped off. I'm going to try some 9gr loads next. Both bullets have approached 1MOA with various loads with gaschecks but neither have ever shot this well!