Just finished fire-forming cases with 4227 and a Hoch 200 gr bullet, 25:1 through my new CPA.  The first 100 in fact..  Although I an experienced 30 cal. reloader I'm a bit nervous with these small-case high pressure loads. 
   I'm getting pressure signs with CCI SP primers at 11.8 to 12.2 gr of IMR 4227, altho cases are not sticking (yet?) with the first firing.   Enclosed is a photo of one of the 12.2 cases; the 11.8 is very similar.    

  I got sub-MOA groups at 100 yards with 11 gr. of W296 averaging 1250 FPS.  Primers are very flat althou not as cratered.

I'd appreciate any advice and observations.  Still looking for AA9 and 4100 out here on the left coast.

My experience after many years of shooting heavy bullets with a .32-20 case and 4227 is to stick around 10 grains.  FWIW.

I load the .32-20 CPA with 13.0 grains of AA4100.  The mv is about 1500 fps.

It takes three firings to properly form the case.  At about 8 firings, accuracy drops off and I look for signs of incipient case head separation.  No case has lasted more than 12 firings at this load.

Despite the rough treatment, I've never experienced primer cratering.

FWIW, I cannot get the the .32-20 CPA to adequately perform with milder loads. 

JackHughs

Try Small Rifle primers the Pistol's have very soft cups.

All good info, thanks.  A very steep learning curve for me.  I will send off the pic to Gail and follow up.  All of your help is appreciated.  FWIW Starline has posted up that their 32-20 should be online April 10.  I've ordered 500 cases.

Hammer rebound........increase the main spring a bit.

A couple of additional questions of those shooting .32-20CPA:
Has altitude differential been considered with respect to load?
Isn't it possible, or even likely, that my 12.5GR of 4100 at 2,400 ft. above sea level will produce comparable results to a 12.7 - 12.9GR load at lesser elevations?  (My chrono says "Yes!") 
When cases start becoming tight to remove after firing, has anyone resorted to full length re-sizing (for the body), expanding the necks and flaring the mouth for precise chamber fit?
JackHughs ....... I'm told that a bunch of the "Modesto .32-20CPAs" have been re-chambered to .32-40; but, yours is in the safe. Have you achieved better results with the .32-40; or might we see the .32-20CPA return?

Your very close, Phil. At the top of the page, I have Pmax [MAP] at 30,458 (BAR 2100), I guess that stuck in my mind  So, I ran QL again, changing the Cross section, bore area to what it gives for a 30/30. My BS depth is .010 ahead of the case. But, that is only 1254 fps with 10.2 gr, 296 (10,923 PSI). I had to increase the charge to 11.6 to get close to my velocity (1408/1410 fps). That gave me a pressure of 14,664 PSI. 

I ran the QL about a year ago and I also measured the case volume and put that in the program at that time (22 gr water)

Frank