It's not a semi-auto, but neither is it a revolver --not really, anyway. An LGS had one of these cannon-breech oddballs on display today, in 45 Winchester or something odd like that and I had to take a look. Weird as all get out, especially the manual of arms of cranking the rear of the breech open (and the fact that this example's safety allowed the striker to drop in both positions, though I couldn't tell if the pin was actually struck on both). I've read the original MR Lone Eagle guns had a cocking lever on the side that had to be used before opening them, but this gun did not, so my guess it was a mislabeled later iteration by another maker (the name escapes me; EDIT: "Competitor"). Personally, I found it interesting as an engineering curiosity, and immediately set to wondering how the striker system (under the barrel) worked, as well as if the thing could somehow be crafted into a semi-auto.
The gun's a tank, nearly 2" or so in diameter at the rear, but these things can fire 30-06 from a breech mechanism the size of a jumbo egg! Pretty impressive, if wildly impractical
. Much lighter than I'd expected, 3-4lbs as I recall with my 'finger scale' and quite handy considering the larger overall size and 10" bull barrel on the thing. You'd definitely want the 30-06 version to come with the muzzle brake 
Anyone ever mess with one of these, or at least know how the forward-mounted striker works to hit the pin in the rear of the gun?
TCB