Micrometer seating die problem

[ronsatspokane]

Was chamber that it was fired in a SAMMI or custom?

SAMMI which means in the ballpark but too much potential variability to be considered a benchmark in my view. It's always reamer dependent both in terms of tolerances and wear. Then of course there is the chamber and the headspace.

 

[ronsatspokane]

Take a picture of your seater stem in the cap where you currently have it set. What bullet are you seating? Vld stem?

Seating the 153.5 Bergers. Yes, it is stem that accommodates VLD style bullets.

 

[Kracken McGraw]

I think that is always a possibility but air is so compressible that you would need to be compressing a lot before you encountered the kind of resistance I'm seeing with this die.

Did your seating pressure ever get any relief before it got to it’s final set length?

 

[ronsatspokane]

Did your seating pressure ever get any relief before it got to it’s final set length?

Once you push past the obstruction it begins to move again but never as smooth moving as prior to crossing the neck/shoulder junction.

 

[Kracken McGraw]

Once you push past the obstruction it begins to move again but never as smooth moving as prior to crossing the neck/shoulder junction.

I will have to test out that air pressure theory sometime. Maybe prime a case with a spent primer and drill a very small hole in the neck, then load as normal to see if that makes a difference.

 

[ronsatspokane]

I‘ve had the stem expand to an interference fit when seating pressure is high. Try sanding the outside of the stem where it contacts the bullet, and roll up some sand paper and polish the hole where the stem rides, start with fine grit for both. Apply a light amount of lube on the stem.

OK, I see what you are saying. I was thinking something entirely different based on the die I was forced to use. I will try this. Waiting for my borescope to recharge so I can get a close look at the interior of the die.

 

[ronsatspokane]

I think I found the problem. The tolerances on the Wilson die allow a relatively precise fit of the 6.5 PRC brass (within a couple thou) and holds it just like the chamber on your rifle would. They obviously cut it with a 6.5 PRC reamer. The question is, which reamer. I suspect that they made their own and it is not quite correct. When I look at the die their reamer cut with the borescope I see a very sharp neck/shoulder junction. When I look at my PTG reamer I see that the junction is eased. When I look at the virgin brass, it matches my reamer. What is going on is that when the bearing surface approaches that junction the die forces the brass to be extruded around that sharp edge to somewhere with space for it to exist.

The solution: I took my reamer and reamed the die by gently hand. Turning the reamer until that edge was eased. I am not a master machinist so I can only say I'm 97 percent certain that will fix the problem. If I were a master machinist I could say that I'm 98.5 percent certain... A little F Class joke.

I'll report back when I get around to loading some test loads. May be later this week.

P.S. while I was at it I took Tod's suggestion and polished that stem so I don't end up fighting another potential issue.

 

[LCazador]

SAMMI which means in the ballpark but too much potential variability to be considered a benchmark in my view. It's alway

s reamer dependent both in terms of tolerances and wear. Then of course there is the chamber and the headspaceI

Running your reamer in the die will probably solve the problem. I've done that on some of my Wilson chamber seaters with great success.