Have been working to get the old Winchester model 43 to print less than an inch and a quarter at 100 yards. Tried the conventional stuff, change bullets, seating depth, powder -

Read that a number of people have used small pistol primers and have had better ignition with better groups. Made up ten rounds of 40 grain Sierra hornet bullets with 9 grains of 2400 and a small pistol primer.

First round went down range with a belch of smoke and the smell of wood in the fire place. Checked the fired round and found a pierced primer. Never had issues with small rifle primers, did not have any issues with rifle primer loads on this putting as well.

Lesson learned - don't listen to all the stuff posted on loading forums. Primers are called rifle primers for a reason. They do have a slightly thicker cup and hold up better to rifle pressures.