What size expander mandrel 6br

[Dimner]

Just to add another way mandrels can be used...

I'm using a 30-06 and 7x57 Forster Benchrest full length resizing die. Was not happy with the neck tension I was getting. I could tell the tension was a too tight when I seated bullets. I was thinking about getting the dies honed, but I had no idea what size to get them honed to. So I added a step into my process where I run the cases in a 0.307 and a 0.283 porter's mandrel (minus tolerance). Made a big difference when seating bullets as well as the SD/ES of my handloads. Did it tighten my groups? I'm not sure, I was in the middle of developing a load. I have a load I like with the 30-06, max extreme spread of 10 with N150. I think it helped my groups but I really have no interest in going back to test.

 

[Jeff Porter]

I did a small sample size (10 rounds each ) of mandrel vs no mandrel in 6BRA with .272 no turn neck chamber using .266” bushing and a .241” mandrel. Not a huge difference on target, both grouped about 0.4” for the 10 shots but the SD was lower (4.5 vs 8 )in the mandrel group. Velocity was a tic higher in the non mandrel set. (5fps) Again small sample size so if we do 30 of each, the difference may disappear.

 

[Retired shooter]

Can't say anything about group size as I was shooting steel. However after full length bushing sizing, and then using 21st century mandrel for final neck sizing. Moly dipped bullet base, I was extremely happy with the results.!
This included temperature change from mid morning to early afternoon.