Author: britrifles
Subject: Case Neck Concentricity
Posted: June 09 2023 at 3:18pm
This die was off from the factory. It’s very obvious just by rolling the sized case on the bench. This puts the bullet off axis with the bore and also off at an angle.
Subject: Case Neck Concentricity
Posted: June 09 2023 at 3:18pm
This die was off from the factory. It’s very obvious just by rolling the sized case on the bench. This puts the bullet off axis with the bore and also off at an angle.
I only use this die to bump the shoulder back, ala partial length resize. About once every 12 to 15 reloads. I think the only reason why accuracy is not terrible with it is it sizes the body of the case considerably, increasing the taper such that there is sufficient clearance at the shoulder of the case with the chamber and the bullet doesn’t get too far out of alignment with the bore.
The new .303 Forester Benchrest die is giving me .002 runout. Much much better.
I also checked my .223 reloads, and those new Wilson dies (full length bushing sizer and in-line seater) produce very concentric cartridges. The Dillon dies I was using gave .015 inch runout at the bullet. They just would not get the 80 gr SMK concentric to the case body. The difference at the target was very noticeable. Went from 9 ring to X ring at 600 yds just by changing out these dies.
A cartridge case concentricity gage won’t fix the problem, but it’s sure a good way find out if case neck/bullet runout is the cause of accuracy issues. It’s not necessary to check your loads with one, unless you’re having unexplained accuracy problems. Some shooters will use them to sort long range loads and set aside those for matches having runout less than .002 inches.