Mold design and bearing length

[HickoryCreek]

In designing a mold what part does bearing length play on the pressure of the cartridge? When the bearing length is higher is the pressure going to be higher all else being equal?

[David R]

I can only give a part of an answer, I know the bigger the size of the boolit, pressure will go up a little and so will velocity. More friction = higher pressure. Its not too much of a difference though.

30 cal boolit sized .308 with 11 grains of Red dot shoots 50 fps slower than sized .310 in my 30'06.

Hope this helps.

[Bass Ackward]

In designing a mold what part does bearing length play on the pressure of the cartridge? When the bearing length is higher is the pressure going to be higher all else being equal?

HC,

Bearing length matters little to pressure. Although the more bearing length, the more weight. And a heavier bullet will throw more pressure. A lot is made of bearing length, but I rather think it is a ratio that is most important. If something isn't bearing length, then I consider it unsupported.

The critical factor as far as I am concerned is to maintain enough ballistic coefficient to make the bullet easy enough to stabilise with the twist rate you are going to subject it to. That's different things to different bore diameters. The easier a bullet is to stabilize, the sooner it will go to sleep when it exits the tube and the more accurate it will be. Not only at close range, but farther out too.

[HickoryCreek]

Thanks for the info guys :-D