Bullet Seating Depth

RidgwayCO · May 26, 2008, 01:27 PM

What do you use to determine the proper seating depths of your bullets?

For me, if a bullet has a cannelure, I use it and the cannelure then determines the bullet seating depth. For bullets with two cannelures (Hornady HP/XTPs are the ones I use), I use the cannelure that fits the gun I intend the load for (biased toward the cannelure closest to the base if possible).

For bullets without cannelures, however, it's not so straight-forward. Currently I seat bullets at least one full caliber deep for rifle bullets (for example, at least .308" deep for my .30-06) , and at least a half caliber deep for pistol bullets (for example, at least .178" deep for my 9mm Luger) . This seems to work fine for me, as I've experienced no bullet setback. But I've recently begun thinking about why these practices work, and should I be seating differently. I'm pretty sure the solution has to do with the relative amount of gripping surface between the case and the bullet, combined with the round's relative recoil.

Your comments are appreciated.

T. O'Heir · May 26, 2008, 01:39 PM

Forget the cannelure and seat 'em to get the OAL you want.

Hawg · May 26, 2008, 01:54 PM

I usually measure a factory round and go from there. Some like my 255 gr. Keith in .45 ACP have to be seated deeper to cycle through the mags.

MADISON · May 28, 2008, 09:47 AM

When setting up a "new" seating die I use one of the following:
[1] Find a factory loaded round and set the die up with it [Pistol/revolver]

[2] For rifles I barely seat a bullet in a dummy case [No powder or primer].
Close the bolt and back off about 1/8th turn.

The Lovemaster · May 28, 2008, 11:02 AM

I put the bullet I'm using in a Hornady OAL gage, measure it, and then seat my rounds to 0.020" shorter. Accurate as hell.

May 26, 2008, 01:27 PM	#1
RidgwayCO Senior Member Join Date: March 22, 2008 Location: Western Colorado Posts: 244	Bullet Seating Depth What do you use to determine the proper seating depths of your bullets? For me, if a bullet has a cannelure, I use it and the cannelure then determines the bullet seating depth. For bullets with two cannelures (Hornady HP/XTPs are the ones I use), I use the cannelure that fits the gun I intend the load for (biased toward the cannelure closest to the base if possible). For bullets without cannelures, however, it's not so straight-forward. Currently I seat bullets at least one full caliber deep for rifle bullets (for example, at least .308" deep for my .30-06) , and at least a half caliber deep for pistol bullets (for example, at least .178" deep for my 9mm Luger) . This seems to work fine for me, as I've experienced no bullet setback. But I've recently begun thinking about why these practices work, and should I be seating differently. I'm pretty sure the solution has to do with the relative amount of gripping surface between the case and the bullet, combined with the round's relative recoil. Your comments are appreciated.

May 26, 2008, 01:39 PM	#2
T. O'Heir Senior Member Join Date: February 13, 2002 Location: Canada Posts: 12,453	Forget the cannelure and seat 'em to get the OAL you want. __________________ Spelling and grammar count!

May 28, 2008, 09:47 AM	#4
MADISON Senior Member Join Date: January 1, 2000 Location: Roanoke, Virginia Posts: 2,678	Bullet Seating Depths When setting up a "new" seating die I use one of the following: [1] Find a factory loaded round and set the die up with it [Pistol/revolver] [2] For rifles I barely seat a bullet in a dummy case [No powder or primer]. Close the bolt and back off about 1/8th turn.

May 26, 2008, 01:54 PM	#3
Hawg Senior Member Join Date: September 8, 2007 Location: Mississippi Posts: 16,188	I usually measure a factory round and go from there. Some like my 255 gr. Keith in .45 ACP have to be seated deeper to cycle through the mags.

May 28, 2008, 11:02 AM	#5
The Lovemaster Senior Member Join Date: December 29, 2007 Location: Arizona Posts: 416	I put the bullet I'm using in a Hornady OAL gage, measure it, and then seat my rounds to 0.020" shorter. Accurate as hell.