Thread: Precision projectile seating

Originally Posted by Moutere

I've always done this on a hunch.
Nice to see someone has taken the time to verify tangible gains in doing so.

Have always done it too, sometimes in 1/3rds. Doesn't seem to make a difference though in some die, cartridge set-ups but it can't hurt.

Originally Posted by 10-Ring

Have always done it too, sometimes in 1/3rds. Doesn't seem to make a difference though in some die, cartridge set-ups but it can't hurt.

Me too. Some fella somewhere recommended just a 90deg turn so i do 3 of those. I'm trying out one of those vld deburr tools atm. Seemed to prevent any damage to the projectile

Originally Posted by 10-Ring

Have always done it too, sometimes in 1/3rds. Doesn't seem to make a difference though in some die, cartridge set-ups but it can't hurt.

Yep, always done it. And likewise, works sometimes.
A lot of things have to be correct/true before seating projectile ie neck runout, consistant beck wall thickness. Don't then expect your seating die to correct issues from earlier in the process.

All commercial dies are cut to SAAMI, but which end of SAAMI tolerance spec? Then commercial chambers are also cut to SAAMI but which end of the spec? I have 2 different brand 308 full length sizing dies. They produce different dimensions along the body of the cases. Reamers as they wear produce ever so slightly smaller chambers. Outcome can be a cartridge case, particularly if full length sized which is a lot smaller than die internals and therefore poorly supported in the seating die. This includes sleeved Redding Comp dies and Wilson inline.

And then there are issues with seating stems both in fit to the projectile and trueness. Have a gaze done your favourite seating die - is the stem central, does it rotate madly around a centre point when you adjust it. Some issues here can be overcome by puting an o ring under the seating stem's lock ring which leaves it to self locate. Likewise for the expander plug if you use one.

Using a std seating stem on a vld projectile can give poor results. I hone my seating stems to a chosen projectile. Problem then is it may not fit another projectile as well.

My worst runout (3 thou) was with a new Wilson inline. I was mighty pissed off. My least runout (0 to 0.5 thou) is with a Wilson inline die that was bought as a blank and then cut at the same time my rifle was chambered with the chambering reamer. Likewise one of my Redding Comp die sets whose sleeves have been "chambered" with the rifle's finishing reamer.

And going back to the OP's original posting, I use a arbor press with force measurement as pictured. You don't need one of these for run of mill ammo loading as I can easily detect different seating pressures with my ancient single stage press.

Now does all this super duper low runout matter. Not for medium range hunting. I have also shot equally high scores in fullbore with ammo that I had relegated to one side due to unacceptable runout versus my best ammo.