Breechplug
I know the BP on the Triumph is a good one, but since the Primer also sits a tad bit above the BP, if one were to put a O Ring under the Primer on the TC's BP then this should really make it work good?
Really do not think it is necessary - I can not get ANY blowback from the Triumph even with a 140 grains of BH. It is the cleanest gun I own..
I posted Lees's picture for you...