308 bushing dies

[FTRinTexas]

What size bushings are being used in the 308 for Lapua and Winchester brass. My loaded Lapua measures .337 and the Winchester measures .333. Is .002 smaller bushing the common trend or .001?

 

[watercam]

.002-.003" for repeating rifles, .001" for single shots.

 

[spclark]

What bushing depends a great deal on your rifle's chamber, your brass treatment, and your particular shooting preferences.

As you indicate, I find I need either to use different bushings for Winchester vs. Lapua .308 / Palma brass or neck-turn Lapua neck walls to that of the thickness of the Winchester.

I prefer the latter while I'm still using both brands. Plan is to move to Lapua over time though necks will still be turned to measure .0127" wall thickness.

If you choose a bushing .001" undersize, you'll need to pay close attention to neck temper. Un-annealed brass won't respond uniformly, particularly when neck walls are thick.

Careful neck annealing is the cure! Annealed brass is soft enough not to spring back so neck diameter will be more consistent.

Even with .002" smaller bushings where indicated, annealing will do much to make your necks more uniform for both loading and shooting.

 

[Scott Harris]

(Final) Bushing size does not depend on your rifle chamber. It depends on the OD of a loaded round measured at the neck and the amount of neck tension needed/desired. Therefore, brass neck thickness, bullet choice, and tension requirements are the primary things to look at. My Lapua 308 brass measures around .015 per side giving me a neck OD in the 308 + 2x.015 = .338 range. .002 under this measurement would be one of the most common choices. Then you could pick extra bushings +-.001 to give you something to play with.

I don't have Winchester brass but know it's a bit thinner. So, unfortunately, you will probably need a separate set of bushings for this brass.

Based on your loaded round measurements above, I'd suggest
.335, .334, .336 for the Lapua brass
.331, .330, .332 for the Winchester brass