375 Cheytac bullet tension

[actionexpress]

I am going to be reloading a magazine fed 375 Cheytac and was wanting to know how much bullet tension should I be looking for.

 

[Big Mc]

I am going to be reloading a magazine fed 375 Cheytac and was wanting to know how much bullet tension should I be looking for.

PLENTY Tommy Mc

 

[big5ifty]

There is a limit to the elasticity of the case neck, beyond which it undergoes plastic deformation, or swages the bullet shank.

2 thou is about the limit in my Norma brass for .375 bullets.

In other words, even if your neck is 6 thou smaller, the bullet will expand the case mouth, and only the last two thou will be the tension part.

If you're going magazine fed for the big guns, don't rely on neck tension to hold the bullet, there is not enough neck tension to withstand the repeated impact of the loaded round against the inside of the magazine, it'll be better to use a crimp. Your last round in the mag will be hammered the most.

Richard Lee once said that anything over 1 thou neck tension either swages the bullet down, or plastically deforms the neck. That I think applies best to 30 cal and below, but the principle remains with bigger bores, just the number differs a bit.

It's a simple test, size your neck, micrometer the mouth, micrometer the bullet, seat bullet, pull bullet, micrometer the case mouth. That'll clearly show how many thou elasticity is in the neck. It'll probably be between 1 and 2 less than the bullet diameter.