Thread: Case neck sizing and effect on accuracy

Originally Posted by Nick-D

From what I've read and observed through my own loading it doesn't have much if any effect on sd. Consistency is key. Kinda doesnt matter which way you size, as long as it is consistent and concentric.

Neck sizing only means the case should be pretty consistent with the chamber and reduces the amount you work the brass in the case. I would expect that over time and multiple reloads the case body and neck will work harden (unless you are also annealing) - the inconsistency in the body sizing versus brass properties should lead to velocity inconsistencies. Though I would expect this inconsistency to be slight.

In my limited testing (243Win and 260Rem, both Lapua cases and without annealing) neck sizing only resulted in slightly higher velocities and slightly more consistent velocities. For a hunting rifle or short distance rifle I wouldn't have seen the results in the groups - only on the chronograph. I saw better results at 500 yards with my 243 in terms of less vertical in the group (full length sized versus neck sized) and better results out to 1000m with the .260Rem with again less vertical.

Two rifles is hardly a comprehensive study though and I didn't prove my theory that repeated full length sizing without annealing would lead to more velocity inconsistency than repeated neck sizing.