this is why carriers are confusing in pursuit of the ultimate goal of weighing up a gun. no one I know in the sport trims guns down. its always up.
just say I/E: your 12ga bbl weighs 3 lbs.
and the total gun with the 12ga bbl on is 7.5lbs.
add a tube set any ga.....figure 1 lb.
now you have a gun weighing 8.5lbs.
great.
but, if you go back to the 12ga bbl, its only 7.5.
so....you add a 1 lb weight.
done.
but....now you have a 7.5 lb 12ga gun with an extra carrier bbl.
you add 1 lb worth of tubes.
so now you have 8.5lb gun PLUS whatever the carrier bbl is.
it WONT match the 12ga bbl set up. itll be off again.
the way I see it is a carrier bbl is only for those who choose to bypass shooting 12ga all together.
which is conflicting since all someone has to do is get a tube set and put any set in the 12ga and leave it...and never load the 12ga ever.
why get another carrier bbl?
answer: gizmo fad.