In the process of switching to Lapua .308 Brass from Federal. When I was working up load noticed neck tension was tighter (only by feel of seating bullet) on the Lapua out of the box. My federal run through RCBS FL dies basically just barely bumping shoulder back .001 is about .002. Normal load for my 168 SMK was 45.0 varget with Lapua it 44.0 varget. Would increased neck tension cause the powder charge difference or would the case itself ? Or both ? The federal brass is actually heavier than the Lapua. I don't have any Chrono for Lapua yet (since I shot the wires holding the sunscreen) Was just curious ?
Neck tension Federal vs Factory Lapua
- Thread starter abadrs
- Start date
Lapua has thicker necks that Federal. By about 0.002-0.003 when loaded according to my measurements. You're going to get more neck tension with the Lapua brass if they're both sized in the same die. Too much neck tension can adversely affect accuracy. The only way to get the same neck tension between those two brands of brass is to either turn necks or use a bushing die. I'm in the same boat right now and I'm going the bushing die route. With the right bushings, I will be able to set the same neck tension no matter what brass I use.
Not necessarily. Bushings may get you the same ID, but differences in wall thickness, alloy, or annealing can also affect the tension. And if the necks are not uniform side to side and/or front to rear, all bets are off. IMO, bushing dies come into their own only when you turn the necks.
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