Inconsistent COL

[rwj]

Theres another issue with the BTO measuring on those bad bullets- youre measuring the ojive at a spot thats totally different than where the seater plug hits. So just for giggles take those need to be sorted bullets and measure total oal, bto, then put your seater plug on it and measure again. The only solution, besides better bullets, is make your comparator the same dia as your seater or make a seater that hits where your comparator does. To really get right with less than perfect bullets, your seater plug AND your comparator should hit on the same diameter as your freebore dia (since thats the part that actually matters)

I wonder why manufacturers don’t revised their dies to have seating stems with a diameter that would result in bullet contact near the ogive diameter?

 

[Dusty Stevens]

I wonder why manufacturers don’t revised their dies to have seating stems with a diameter that would result in bullet contact near the ogive diameter?

Not real sure but it would be nice

 

[Shinbone]

I had this COL problem with pretty much every bullet type I loaded with a single stage press bullet seating die. I tried both Redding and Forster dies, to no avail. This happened with multiple different bullets with multiple different cartridges. Turns out that the bullet was pretty much always sticking to varying degrees in the seating stem. The bullet would then be partially withdrawn from the case before unsticking as the cartdige was withdrawn from the die. Sometimes a little. Sometimes a lot. I found that lapping the seating stem to a particular bullet helped, but did not entirely solve the problem. I almost always had some degree of "sticktion" and some amount bullet withdrawal.

I finally switched over to an arbor press and inline dies for my bullet seating step. An inline die allows you to "break loose" the bullet from the seating stem, if it is stuck, before withdrawing the cartridge from the die. I can now see/feel that almost all bullets stick in the seating stem to some degree.

Plus, I no longer measure to the bullet tip, especially with non-lathe-turned bullets. I now measure to the ogive with a bullet comparator. This gives a much more consistent measurement.

I am now able to hold case bottom-to-ogive length to within .001" for any bullet and any cartridge.

 

[acloco]

I have noticed that I am getting an inconsistent COL. Rockchucker press, RCBS dies, 7mm-08, Hornady brass, 139g SST. The charge is not compressed.

the brass is sized and the primers are seated correctly. The seating die is screwed into the press to the nut T the desired depth and the hex head keeper screw is installed and tight.

I have only been hand loading for a few years. What might I have missed that can cause this? Gracias.

Is the plastic tip of the bullet contacting the interior of the seating stem? This is quite common with seating stems.

Easy to check - coat the tip with a black sharpie, allow to dry, and seat bullet in a piece of brass.

Could probably check a loaded round in the same method, without seating another bullet.

 

[johara1]

That is what they make lathes for fix seating stems, no big deal what is a big deal is bullets that vary in length for very well know bullet makers over .060 in a 100. When the A tip varies +-.001 in length.. First take your seating stem out and place a bullet in and see where it seats, if the nose is hitting, it will need attention. If not measure your bullet's length for a hundred, you will get your answer...... jim

 

[JFrank]

View attachment 1216425

Pic stolen from here years ago. this is your problem. Die dimensions dont move unless something is loose which you verified. Measure the ogive and oal like i said earlier and youll see the difference.

Hard to imagine those all coming out of the same box’ I would suspect multiple sources involved.

 

[urbanrifleman]

Annnddd donuts.

(I'll just leave this here)

 

[Dusty Stevens]

Hard to imagine those all coming out of the same box’ I would suspect multiple sources involved.

Just shows how lot numbers matter none on factory bullets

 

[johara1]

My measurements came out of the same box and the same lot, totally unacceptable for a custom bullet.

BTW.... it sure wasn't Barts...... jim

 

[Richard Coody]

I had this COL problem with pretty much every bullet type I loaded with a single stage press bullet seating die. I tried both Redding and Forster dies, to no avail. This happened with multiple different bullets with multiple different cartridges. Turns out that the bullet was pretty much always sticking to varying degrees in the seating stem. The bullet would then be partially withdrawn from the case before unsticking as the cartdige was withdrawn from the die. Sometimes a little. Sometimes a lot. I found that lapping the seating stem to a particular bullet helped, but did not entirely solve the problem. I almost always had some degree of "sticktion" and some amount bullet withdrawal.

I finally switched over to an arbor press and inline dies for my bullet seating step. An inline die allows you to "break loose" the bullet from the seating stem, if it is stuck, before withdrawing the cartridge from the die. I can now see/feel that almost all bullets stick in the seating stem to some degree.

Plus, I no longer measure to the bullet tip, especially with non-lathe-turned bullets. I now measure to the ogive with a bullet comparator. This gives a much more consistent measurement.

I am now able to hold case bottom-to-ogive length to within .001" for any bullet and any cartridge.

You must use a lot of neck tension to stick bullets in the seater stem. Does the seater stem leave a ring on the bullet.

You might try a little lapping compound on a bullet and lap that seater stem a bit.

 

[johara1]

You must use a lot of neck tension to stick bullets in the seater stem. Does the seater stem leave a ring on the bullet.

You might try a little lapping compound on a bullet and lap that seater stem a bit.

If you are leaving a ring you need more than lapping compound, BTW what will wear first the bullet or the steel seating stem? A drill and super sharp tool steel bit works better dialed in on a lathe...... jim

 

[Shinbone]

You must use a lot of neck tension to stick bullets in the seater stem. Does the seater stem leave a ring on the bullet.

You might try a little lapping compound on a bullet and lap that seater stem a bit.

Neck tension is/was .002."