Bullet seating depth

[VolFan9183]

Hi everyone-

I have a question regarding the variation in bullet lengths and its affect on seating depth. 

I'm working up a load for my 7mm-08 using Sierra 140 gr ProHunter bullets.  I've noticed there is a slight variation in the length of individual bullets, and I'm guessing it's due mainly to the lead tips on the bullets.

I'm wondering how this will affect the seating depth of each cartridge?  I'm using Lee dies, and the bullet seating die appears to have a "cap" inside the die that contacts the bullet near the ogive of the bullet, and controls the seating depth.

Will I be better off making each cartridge the same OAL (assuming each is under the maximum recommended OAL), or should I set my die using a dummy cartridge, and leave it alone?  I'm leaning toward the latter, since it would theoretically give the same bullet jump each time since the seating depth appears to be based off the ogive of the bullet.  I'm just thinking that if I make each cartridge the same OAL, the actual bullet seating depth could vary since there seems to be some variation in the length of each bullet tip.

Hope this question makes sense...thanks, in advance, for your advice.

[Luckyducker]

VF, the tips on bullets will often be inconsistent, unless they are the polymer type, and their variances should not be considered when setting the COAL of cartridges.  The depth should be set so that there is a uniform distance from where the bearing surface of the bullet first contacts the barrel lands.  Once OAL has been determined and the seating die has been set correctly there is no need to measure each cartridge unless something changes such as the plunger in the die is accidentally turned.  The seating die can be reset by placing  a loaded or dummy round into the shellholder in the  press and with the seating plunger backed out screw the die into the press until it just makes contact with the cartridge, then set the lock ring.  After this has been done screw the plunger into the die until you feel it touch the bullet and the die will be set to prevous dimensions.

[skweeker64]

You are correct about the tip being your variable. Do your self a favor, take a 3/4" bolt cut it off so it is about 1 to 1-1/2 inch long. Drill a .220 hole about a half inch deep from the bolt end towards the hex end. then mill a groove in the hex head that will fit snug on your caliper, and drill and tap a hole for a thumb screw to attach it to the fixed side of your calipers. This way you always measure from the same point on the ogive. It is so much easier than trying to measure from the tip.

[beemanbeme]

The "cup" is there for the reason you outlined.  You are making uniform ammo. It is just varying in overall length because of the exposed lead tip.  Don't worry about it. If it will fit in your magazine, you are good to go.
To be sure you can blacken one of the bullets in a finished cartridge with a magic marker and chamber it.  Remove it and look closely at the bullet. It shouldn't show any engraving marks from the lands of the rifling. Don't mistake random marks from sliding into the chamber for marks from the lands. If the bullet is touching the lands the marks from the lands will be spaced equally around the bullet.