Here's my take on Knight breech plugs used on my 45cal Disc Elite:
I’ve been using the three different breech plugs:
http://www.huntingnet.com/forum/tm.aspx?m=1422392
Standard – works great with small amount of blowback.
Domed – about 25% of the standard blowback, but detonates/blows-off the tops of most of the primers. This causes the primer tops to lodge inside the bolt spring assembly, and will foul up the firing pin movement. I plan to do some precision measurements and possibly some modifications to this plug in the near future. (This was happening with only 80grns of APP/Shockey's Gold)
Power Stem – Less blowback than standard using 120grn by volume powder charges. Burns the powder charge about 3x more efficiently! Leaving only 25% of the standard/domed plug residual barrel fouling!! It shocked me to only use 1 wet patch and 1-2 dry patches
I was worried that the 2 inch breech area used up by the stem would get real cruddy. But after 50 shots of Pinnacle the breech area looked great, and was cleaned with 1 wet patch