22-250 8"twist Seating depth

[Iron Worker]

Just bought a Hornady "Lock-N-Load" Straight O.A.L. guage . This rifle will be dedicated to shooting 65gr-80gr bullets, with an occasional 60gr V-max. So starting with 69gr Sierra TMK bullets . Following the directions C.O.A.L. is 2.453 ,then using a 1" Sinclair Bullet comparator at the OGIVE it measured 1.979. I've been advised to seat bullets .015 away from lands and move.005 into lands until touching . Gunsmith that chambered this rifle said He could lengthen the throat if needed . So my question is, is lengthening the throat needed ? Why would I want to do this ?

 

[Gene]

With an 8" twist, I assume this is for a custom barrel. In a factory barrel, most throats are so long that it is impossible to reach the lands. Adding length to the throat will allow you to put more powder in the case. But, you may not be able to touch the lands with very light bullets.

The 8 twist will work well for heavy bullets - say 55 to 70 grains. I like to start my loads just touching and move in and out from there with .005" adjustments. As a base, use the average of 5 measurement to determine where you are touching, and write it down. Most factory bullets will differ some in position of the ogive.

 

[sourdough44]

What particular loads shoot best can be an individual thing, with similarities. As mostly a hunter I don't care to have bullets 'touching' the lands. All it takes is a slight variance and you get a bullet pulled and then stuck while unloading a round. Yes, I've seen it happen, luckily the deer was dead.

I always measure Max COL with a given bullet, then compare it to the magazine and book lengths. My measured chamber COL is usually what I then go by, time for testing at the range.