Need to borrow some expertise from long time reloaders. For some reason , I can’t get my seating die to repeat my desired setting. Sometimes it will be off as much as .005– sometimes it will repeat, but not as often as it should. What are possible reasons? I’m using a Forster ultra micrometer— so quality shouldn’t be the problem.
Are you measuring OAL to bullet tip, or to ogive with a comparator? Tips can vary.
Are you talking about variation cartridge to cartridge, or session to session?
Maybe the amount the die is tightened? Or the micrometer gets bumped a bit. Does the micrometer lock?
Cartridge to cartridge— yes it does have lock ring and is locked
Neck tension variance will cause that as will bullet variations.
I don't know if it's possible for the meplat to be bearing against the inside of the seater stem, but if it IS, then that could cause variation too.
I think work-hardened case necks is the most likely possibility.
I took the seater off the press and started over. This time I worked up some Barnes 130 gr ttsx bullets. Put seater back on press and adjusted it according to instrutions. Worked fine maybe occasionally off .001 to .002 off, but not really a problem. Thinking maybe there was something about the fit of the seater and the Norma bullet that caused the bullet to be pulled out a smidge on the down-stroke. The outside of the Barnes probably a little harder than the gilding material on the Norma, so less chance of sticking. Feel better about equipment anyway— thanks to all for input—Bill
I've heard of polishing the inner rim of the seater plug. That might help with your Norma bullets...maybe not, but worth a try. Maybe.
As a relatively new reloader, I had a lot of trouble with varying bullet seating distances between different cartridges in same reloading session. I use my comparator to do measurements, which of course means my measurements are taken from the olgive. I found myself checking seating depths and making adjustments for each cartridge - which was ridiculous.
So I took my seating die apart to see what was going on, and it turned out the problem was that my seating plug was pushing against the meplat rather than the olgive to seat my bullets. It turns out that meplats on my hornady interlock bullets vary a lot, and I think that’s a big problem when I’m trying for consistent 20 thousandths from olgive to the lands.
My solution was to drill out my seating plug and polish so it contacts the olgive rather than the meplat. This was actually very simple because my seating plug turns out to be very soft aluminum. All my seating distances are consistent now.
I'm rethinking the need to get all the ogive lengths the same. When using .308" 168 gr. match bullets from Sierra and Hornady when the ogive length is the same the OAL varies about .010" - .015".
I measured the OAL and ogive length of some GP-11 7.5 Swiss ammo which works great in my K31. I measured the ammo to see what ogive length I needed for hand loads to work in my rifle. The OAL given in the load manuals works for the magazine, but is about .100" to long to fit the chamber. What I found measuring the GP-11 ammo was that the OAL was nearly identical between cartridges, but the ogive length varied about .010" - .015" like the OAL of the 168 gr. bullets loads.
The GP-11 ammo measures like the bullet tip was what was contacting the seater of the equipment used to make this ammo. In spite of this wide ogive length the ammo shoots as well as any of my handloads in this rifle. Bear in mind this is being shot in a rifle with open metallic sights, so distinguishing small differences in accuracy is difficult. I haven't yet tried experimenting with this difference in other rifles, but plan on looking into it.