I switched the number 11 cap breach plug on my Knight 54 cal muzzy with a 209 breach plug and bolt. I have a bunch of CCI 209 mag primers that I sighted in the muzzy with but now I am getting powder blow back from the primer as well as the inside of the primer cup is pushing back. Looks like over pressure, should I back of and use standard primers or I have heard of guys drilling out the breach plug hole a little bigger. My load is 100 grains of pyrodex under a 300 grain .45 cal lead slug in a sabot.

Do you think switching to another primer will effect my POI all that much? I have a hunt coming up and no time to sight in the muzzy?

use the Winchester 777 muzzleloader or a standard CCI 209 primers. mag primers are too much.

some companies have stated that standard 209's will actually cause a slight hesitation of firing due to the fact they initial firing of the primer blows the powder charge further into the barrel before ignition. I have not encountered that with any of my inlines.

I use standard CCI 209 and have 4 packs of the Winchester 777 primers in my shooting box.