Depends on what you want. If on a NEf Ultra 12ga, with heavy
barrel,250 bucks for gun, 100 dollars for 10 3.5"cases from RMC,
few dollars to lengthen chamber to 3.5", add weight
to gun, few dollars for add on recoil pad.
If you want a Savage 210 they are $550, plus heavy barrel
for 300, gunsmithing and chambering extra. Plus pad and
cases. I don't do it but you can have your smith do them.Ed