Andy
02-09-2017, 09:26 PM
So, I did my first impact slug chamber casting and I'm looking for advice on how to measure it/use it to improve my loading specs.
Just to make sure I'm describing it right I mean the method where you fill a fired case 1/2 way with pure lead, chamber it, then drive a long slug of pure lead down the barrel onto that and hammer it until it fills the chamber fully in every detail. You then carefully remove this item, which is now a one-piece lead/brass chamber casting, and you have something you can take chamber measurements off of.
My issue is this: I don't really know how to take/interpret precise measurements off this casting in a way that helps me adjust my load accordingly. I have excellent micrometers and calipers it is just hard to actually take a repeatable measurement of the diameter at a given length.
For example, I have a rounded ogive bullet, this is in .380, that I'm trying to determine optimum seating length for. I speculate that I may be occasionally encountering failure-to-feed problems due to the nose of slightly oversize cast bullets (nose isn't affected by lube-sizing of course) hitting the throat/rifling. I hoped the chamber casting would shed some light on these issues but the tolerance is so small I feel like I can't measure it well.
Are there any tips/tricks you guys have for how to use/measure a chamber casting?
I though the chamber casting would easily lead me to an optimum seating depth but it is very hard to estabish/measure to a given line on an ogive bullet in a repeatable way.
Just to make sure I'm describing it right I mean the method where you fill a fired case 1/2 way with pure lead, chamber it, then drive a long slug of pure lead down the barrel onto that and hammer it until it fills the chamber fully in every detail. You then carefully remove this item, which is now a one-piece lead/brass chamber casting, and you have something you can take chamber measurements off of.
My issue is this: I don't really know how to take/interpret precise measurements off this casting in a way that helps me adjust my load accordingly. I have excellent micrometers and calipers it is just hard to actually take a repeatable measurement of the diameter at a given length.
For example, I have a rounded ogive bullet, this is in .380, that I'm trying to determine optimum seating length for. I speculate that I may be occasionally encountering failure-to-feed problems due to the nose of slightly oversize cast bullets (nose isn't affected by lube-sizing of course) hitting the throat/rifling. I hoped the chamber casting would shed some light on these issues but the tolerance is so small I feel like I can't measure it well.
Are there any tips/tricks you guys have for how to use/measure a chamber casting?
I though the chamber casting would easily lead me to an optimum seating depth but it is very hard to estabish/measure to a given line on an ogive bullet in a repeatable way.