COAL Measurments very sometimes

[0321jarhead]

Today while reloading some 7.5X55 with 180gr Sierra HPBT MK, I had my die set to measure 2.923. I would measure each round after completed. Every now and then my OAL would vary sometimes by .005 (-+). Whats up with that. I'm using a Lee Breech Lock Challenger press with a Lee die. I only neck sized the casings for that I will use them again for the same rifle. These casings are PRVI and are on there 2nd reload. I did notice that some of the points on the bullets were not even. I have a feeling that that may be the problem. I have some Sierra Game King that has a flat head on the tip. That will be my next few loads that I will try. And hopefully measurements will be exact. Anyone else ever run into something like this?

[CEDaytonaRydr]

Seating dies seat off Ogive, not from the tip of the bullet. You're fine...

[CK_32]

SMK explains it all.

But that's normal it's called ogive.

[Enfield47]

Seating dies seat off Ogive, not from the tip of the bullet. You're fine...

Not all seating dies seat on the ogive. I am using RCBS dies for my 7.5x55 Swiss and they seat above the ogive. I tested it with two different bullets and measured them with the Hornady ogive measuring device and both were different.

OP it is probably the bullets that are causing the variations in COL that you are experiencing. I measured several HPBT bullets from the same batch one day and they had variations in length due to the tip of the bullets. You could get fancy and correctly point each bullet, but it isn't necessary for most shooting applications. You will be fine with a little variation.

I'm curious to know how the neck sizing only is working for you. I was told it was best to FL resize for the straight pull action so the cases extract properly.

[0321jarhead]

I'm curious to know how the neck sizing only is working for you. I was told it was best to FL resize for the straight pull action so the cases extract properly.

The neck sizing has been without any issues. Been using those rounds in the same rifle. The cases have been extracting as they should.

As far as the "OGIVE" goes, that is something that had crossed my mind. Makes sense now. Thanks reloaders!

[BLR81]

First off .005" is no big deal unless your using a custom chambered bench rest setup. As Enfield47 stated, the seating stem contacts the nose of the bullet in front of the ogive. And, most bullets manufacturers can't make every bullet exactly the same. The nose and tip will vary.

I have the LockNLoad bullet comparator which does measure off the ogive, and just measuring the bullet, I can find variations in length and distance from ogive to base.

But it should be noted that if you load very close the the lands, your long bullets may touch the lands and create higher pressure than normal.

[Exodus343]

First off .005" is no big deal unless your using a custom chambered bench rest setup. As Enfield47 stated, the seating stem contacts the nose of the bullet in front of the ogive. And, most bullets manufacturers can't make every bullet exactly the same. The nose and tip will vary.

I have the LockNLoad bullet comparator which does measure off the ogive, and just measuring the bullet, I can find variations in length and distance from ogive to base.

But it should be noted that if you load very close the the lands, your long bullets may touch the lands and create higher pressure than normal.

+1 for the bullet comparator
when I was just measuring the entire round from rim to the meplat it was SOOO inconsistent

now using that bullet comparator I segregate the bullets into separate batches depending on the measured ogive length

then I load em up, and measure each finished round and I get about 0.002" of variances both +/-