Standard Steel Neck Bushing sizes .300 -.375
Standard Steel neck sizing bushing that can be used with a Full length sizing die or neck die. Various sizes available in 0.001" increments covering a wide range of calibers.
To Calculate the bushing size you require, measure the neck diameter of the cartridge where the seated round sits in the neck and take this measurement (Example 0.339") Now subtract 0.002" or 0.003" from this measurement and this will give you a size of a suitable bushing.
0.339 - 0.003 = 0.336"
Another method of calculating neck bushing size can be done by measuring the neck wall thickness of the brass and multiply this by 2 and then add the bullet diameter, once you have this number you can subtract 0.002" or 0.003" to get the bushing size.
Brass wall neck thickness x 2 = 0.029"
Bullet diameter 0.308"
(Example)
0.308" + 0.029" = 0.337" Now subtract 0.003" = 0.334" bushing size
(Please note) some brass cases will become hardened with use a lot more than new or once fired brass and a small amount of spring back can be seen at times in the necks so if you have older brass that's not annealed, we suggest going a slightly tighter bushing.