Yes, but off hand I don't recall what the firing pin spacing is. The measurement across the water table is virtually the same as an 8 lb G. I have heard of some 12 gauges built on the XX frame but this one was not.

On my 16 gauge on the XX frame the bar is both narrower & shallower than non XX frame.

My experience is that heavier Lefevers have a wider & taller breech with corresponding thicker walls around the chambers & a wider firing pin spacing.

Some time back in a discussion on this I measured all of mine & posted the dimensions. They are I suppose still somewhere on the forums here, but I'm not very good with the searching aspect of the board.

Miller/TN
I Didn't Say Everything I Said, Yogi Berra