The 780 model looks alot like an 870, but on closer inspection it becomes evident that it's much more roughly done, and that none of the parts are interchangeable.
The Marstar HP9 is much, much nicer, though I'd been told by the people at Epps that only the internals are interchangeable with the Remington parts, not the barrel. To test this, I tried putting my 870 smooth bore slug barrel on it and found that it wouldn't go in. That said, I tried the same barrel on a Canam Grizzly and it fit just fine.
