Here is picture my NEF, soon to be, 8ga gun.
It weighs 15 lbs. The hollow butt and hollows
in the forearm are weighted. It has a neat recoil
barrel ring I added so forearm stays put.
It has internal brake on barrel that I picture
earlier in thread with the porting holes.
Second picture is a Lyman 520 gr slug on the right
that we are testing . They go in regular 12ga shotcups,
and many folks have good accuracy with them, even
in smooth bores. They are hollowbase nose-heavy
design. These are the ones you cast your own.
And there are guys casting some for sale.
On the left is my prototype of the Lyman
style, of 900gr for our 8GA FH. Going to get a
mold made. The base of it will fit the 8ga shotcup
used in the kiln gun loads, and the front will be our
smoothbore 8ga size, .832-835". I designed this
as the flat ended kiln slug wasn't designed
to give accuracy in a smoothbore. Ed