08-16-2020, 02:02 AM
65newloader Wrote:Went by the measurement of what did not fit the chamber of 1.2315. Bump it back to 1.211" and it all cycled. Every one without a problem. I am going to remove ejector pin on the bolts tomorrow and test to see what chambers and what does not. I checked every round on the shoulders when I made them and they fall, according to what I was getting, within .001" of 1.211". If I am looking at .003" to .005" set back from the fired brass, this would put me right near the 1.211", especially at .005". But, when is it too much? I will keep on investigating the specs I am getting. If I have to make a new modified case to go by, I can do that. Thanks for the suggestions.
Again your modified cases length is of no importance to the issue and task at hand.
You only need 3 to 5 thousands bump on a fired case. So if your fired case is 1.2315 you need to be in the 1.228 to 1.226 range for proper shoulder bump.
3 thousands is min you should bump and 5 thousands is max you should bump. Anymore then 5 thousands and your over working your brass and shorting its lifespan. Any less then 3 thousands and you run the risk of not being bumped enough too fit the chamber and have easy extraction.
If your fired case us coming out at 1.231 and your bumping back too 1.211 your bumping it 20 thousands. That's way over working the brass. And that's a lot and I mean a lot of stretch.
Are you sure you have the correct bolt for your barrel? I haven't seen any of my barrels ever have that much stretch.
What tools are you useing to measure?
What die?
What press?
You dont need to remove the ejector pin, drop a empty sized case into the chamber and let the bcg run home, then try to extract it.
If it doesn't close, you need to bump the shoulder back, if it is ruff/hard to extract, bump the shoulder back.
Use the case with the longest measurement. Unlock your die and back it way out, then adjust it in slowly between each trybin the chamber till you find it chambers and extracts easily.
If your cases are at 1.231 to start you should find good clambering and extraction at 1.228 to 1.227. That's 3 to 4 thousands shoulder bump.