OK - My typical Field Pistol load for a .22 Hornet in a 10" T/C is a CCI SR primer, 4.6 gr's of WW231 in a RP case under a 55 gr. Hornady FMJBT that gives me 1" to 1-1/2" groups at 100 yds - fine for IHMSA. I will start using WW296 (8.5 gr's) for the rams though. Damn ringers - the rams need that extra oomph the 296 gives !

ANYHOW - my buddy suggested that a pistol primer would be better for use with the 231. I made five up with exactly the same components and powder - except I used CCI SP primers.

I shot 10 (SR primer) rounds to warm up the barrel. I got a a 3/4" and a 1/2" group at fifty yards. I then shot the (5) rounds with the SP primers. I got the most perfect horizontal string I ever did see! Elevation was damn-near perfect (right on the center line), but each shot was almost an exact 1/2" apart left to right.

I chrony'd these too - not that much of a difference than the SR primers.

This was not a wind thing. This was not a sight thing either as I had a 3-9x Bushnell set at 6x on the KL rail for the days' load testing. It HAD to be the primer difference - at least in my mind it does! I went back to rounds with the SR primer - no problemo - nice groups.

Anybody else experience this? IS this all primer ya think ??

Thanks. I'm eager to hear some theory AND experience responses from y'all !

Anything you can't explain try again three times under the same conditions. Most of the time you can see if it was a fluke of nature or something else. Then you can start trouble shooting.
Just my opinion.