OP
OP
Tumbleweed
Lil-Rokslider
Hey all, wanted to give an update on the project. The barrel now has 215 rounds on it. Keep in mind the first 100 were just a light, fireforming load with no load dev whatsoever.
My last update showed the results of the powder charge tests with Fed215M’s and Retumbo. The ES was a little higher than I like. I started by testing some different “neck tensions” of which made no impact on ES. So, I went on to test CCI250’s and even CCI200’s with their own charge tests to see if I could get ES down under 20. CCI250’s were about the same as the Federals and while the CCI200’s tightened up ES some, the powder charge accuracy window became extremely narrow. Too narrow for my comfort.
Towards the tail end of this testing, the barrel sped up a little. Velocity went up 15-20fps and groups opened. I ran another powder charge test with Fed215’s and trickled it back down until I was in the sweet spot again. Side note…I’ve been mocked for this, but this target shows exactly why I test in 2/10 increments at times when it’s a lighter profile barrel with heavy bullets. It matters. You can see the incremental change to group size that happens.
Today, the ES was down under 15 on all of these charges, maybe the barrel internal landscape has something to do with it? Time will tell. My next step is to take it to 1000 plus yards and see how it holds vertical, that will be telling. Could be a bit before this nasty, coastal weather allows for that. That should be my next update!
My last update showed the results of the powder charge tests with Fed215M’s and Retumbo. The ES was a little higher than I like. I started by testing some different “neck tensions” of which made no impact on ES. So, I went on to test CCI250’s and even CCI200’s with their own charge tests to see if I could get ES down under 20. CCI250’s were about the same as the Federals and while the CCI200’s tightened up ES some, the powder charge accuracy window became extremely narrow. Too narrow for my comfort.
Towards the tail end of this testing, the barrel sped up a little. Velocity went up 15-20fps and groups opened. I ran another powder charge test with Fed215’s and trickled it back down until I was in the sweet spot again. Side note…I’ve been mocked for this, but this target shows exactly why I test in 2/10 increments at times when it’s a lighter profile barrel with heavy bullets. It matters. You can see the incremental change to group size that happens.
Today, the ES was down under 15 on all of these charges, maybe the barrel internal landscape has something to do with it? Time will tell. My next step is to take it to 1000 plus yards and see how it holds vertical, that will be telling. Could be a bit before this nasty, coastal weather allows for that. That should be my next update!
