Shot 5 

It's a generation 1 AYDT with the exposed extracor, I have a 2nd generation. Up around 15gr of 4227 is getting warm on these actions, I'd suggest you start around 13 grains and work up.

Hey tim_s,

   I have always wondered how one would know that they are getting to the upper limit on pressures for these actions.  I have not been able to get a good brass to chamber seal even with 15.5gr 4227 and I figured if the brass is not expanding that the pressures must be relativly low.

Shawn

Tim S; 
  You said a generation 1 is there more info about these early rifles ??
Randy

Ace,

   Alte scheibenwaffen  Old german target arm Volumes 1-3  by Jesse Thompson, C. Ron Dillon, Allen Hallock, Bill Loos and compiled by Tom Rowe.  Has a lot of great information and wonderful pictures.

Shawn

SKS.
  I have been told to the primer , if it starts to mushroom the pressure is getting to high.Also impressions from the the bolt will also indicate high pressure

Randy

I'll second (or third? or fourth?) the recommendations of the Dell and Schwarz book, and the Alte Schiebenwaffen books.  That three volume set is quite expensive, but some of the most in depth and gorgeous photography of any such book I'm aware of.
Terrific pictures and loads of info.

I get soot blow by of the brass too...   
I think it has more to do with pressure vs time rather than total pressure.
That is, if the peak pressure is reached early, before the bullet has moved much, it will expand the neck and seal before the neck gets all cruddy.  If peak pressure is reached later, then the gas has already icked up your brass.
That's just an untested, unresearched, theory of mine... 
I just keep a piece of scotch-brite pad in my ammo box, and clean them after I shoot 'em. 

Paul F.