wow that is a very good shot there,hahaha, very nice. u should with a few other pics be able to set up and get ur own one built soon. u might be able to contact them for some info on the pieces they have, see if they will help u in you endevor to build one the same.
I know that the upper pivoting portion of the carriage has to endure alot of strain to absorb the recoil, they infact have this as what look like a single piece of wood, now that not a problem to make it.. one or several pieces depending on your resourses.
They have what looks like just straps to hold the barrel down to the 'cradle' and the breach is hammer wedged against the end of the barrel.
if it were me doing this I would probable have the barrel with its own straps or some how atached in a basically permanent setup, i wouldnt want the barrel to go sailing down range somewhere after i touched off a shot
Building this and making it a golf ball bore size, or like a 1# ball size would be really nice.
with that size the weight is there for the piece but when u have to haul it home it wont be super big or heavy.
Im not too sure what steel wheels are to tell u the truth. I havent any idea what u would use on a piece like this, u could if it works, or not really care how accurate the piece is, but then who cares really, it make noise smoke and ur having fun... :thumbsup: :thumbsup: :thumbsup: