I am loading some ammo for my 416 Rigby and am using Barnes bullets. Reloading Manual #4 reads: Case Trim Length: 2.890", but the diagram shows 2.900.

How critical is this and why the difference?

When I measure my cases some are as short as 2.85 and some as long as 2.93. Need I be concerned?

quote:

Originally posted by SBT:
I am loading some ammo for my 416 Rigby and am using Barnes bullets. Reloading Manual #4 reads: Case Trim Length: 2.890", but the diagram shows 2.900.

How critical is this and why the difference?

When I measure my cases some are as short as 2.85 and some as long as 2.93. Need I be concerned?

Any case over 2.900" needs to be trimmed, is the maximum length allowed. Any thing shorter is ok, but try not to go below the 2.890" Taking .010" off is standard for most all rifles. If you case get to long the bullet get pinched into the chamber, this can raise pressures and do dammage to your rifle. Always flrs first then trim to length.

For any case that need to be crimped all cases should be trimed to the shortest common length. I had similar trim discrepencies with my 404 having from 2.845 to 2.870for .031 difference and they are all trimed to 2.845.
Von Gruff.