Adjusting for Different Bullet Length

[ESquared]

Total newbie question and maybe a longshot, but is there a general rule of thumb about how much to back out or advance the adjuster on a bullet seating die when going from one length/bullet weight to another?

For example, I'll be moving from the 110 gr Hornady XTPs (357 mag) to 158 gr XTPs and the difference in the length of those two bullets is 0.167". Any idea about how many turns of my adjuster knob on top of my Lee bullet seating die to get close to my desired OAL? I know I'll need to fine tune, but was just looking for a good place to start...

HOpe the question makes sense and thanks in advance!

[Cofisher]

I ran into different seating depths also. Use the COAL to adjust for depth. I learned to accept a shorter COAL to get a proper seat and crimp. I know this may affect accuracy, but am using it as a learning curve point.

[Ojaileveraction]

What is your desired OAL?
Hodgdon list 110xtp 1.59 and 158xtp at 1.58. So your taking a 100 of an inch difference.
That I think equals about one turn of the die.

Seating depth a factor of overall length.


357 is on the husky side of bullets the difference in length between weights is not as drastic as say .224 bullets.

[CT_Shooter]

I'll be moving from the 110 gr Hornady XTPs (357 mag) to 158 gr XTPs and the difference in the length of those two bullets is 0.167". Any idea about how many turns of my adjuster knob on top of my Lee bullet seating die to get close to my desired OAL?

It is my understanding that the OAL for each of those two bullets should be the same (according to my Hornady manual) and should locate the top of the case in the middle to the top of bullet's cannelure (1.590" maximum). The length of the bullet outside the case should be the same; the length of the bullet inside the case will be different.

[Cofisher]

I started with hornady XTP and had no trouble with the 1.59. After that, the zero bullet required a shorter COAL due to the position of the canelure (sic). I ended up with a 1.58, or so. After talking with my lgs guy, I learned this was ok. Again, learning curve.

[220]

If they have a cannelure it is pretty easy you just seat and crimp to it unless you have a good reason to do otherwise.

When I have a die set with my desired level of crimp and want and swap to another projectile my procedure is as follows.

Back the die out 2 full turns
Run a case and projectile into the die. Bullet should be seated long with no crimp.
Adjust the seating stem to get the seating depth correct. Bullet should be seated to the correct depth with no crimp.
Back the seating stem out and screw the die back down. Run the round back into the die and it should be seated to the correct depth with your desired crimp.
With the round in the die screw the seating stem back down until it contacts the projectile and everything should be set for the new bullet.

[Jdl447]

I measure from the nose of the bullet to the cannelure than add or subtract the difference to the length of the die.

[Cofisher]

After the XTP bullets, I found that the Zero bullets, set at the same depth, did not seat to the canelure. I had to seat them deeper to match the groove. It was only 1-1.5 one hundredths difference. But notable.

I don't expect much, if any, difference in performance.

[ESquared]

That all makes total sense, now that you've explained it so well, thanks to all. I'll double check the measurement from the tip to the cannelure, but I think the idea that you just push the rest of the projectile further into the case means that you don't need to fiddle too much with the seating depth adjustment (at least in this case, with them both being Hornady XTPs, same caliber, etc.).

Duh. Told you it was a newbie question.

Thanks again!

[JEBar]

It is my understanding that the OAL for each of those two bullets should be the same (according to my Hornady manual) and should locate the top of the case in the middle to the top of bullet's cannelure (1.590" maximum). The length of the bullet outside the case should be the same; the length of the bullet inside the case will be different.

bingo ..... the cannelure on the bullet is put there by the manufacture .... it is designed (in part) to line up with the open end of the case, thus the OAL standards are met .... being off by a hundredth or two is well within understanding