To OTTO & all,

What is the minimum diameter of the exterior of

the bbl at the muzzle as compared to the bore size? IE. to

fire a .375 bullet, what is the minimum diameter of the bbl

at the muzzle, .625 inch, a quarter of an inch larger than

the bullet? Would this be a constant? With a 600NE using a

.620 inch bullet is the exterior bbl diameter at the muzzle

.870 inch? I guess what I'm asking is HOW THICK do double

rifle bbl WALLS have to be, AND is this a constant figure or

must the walls get thicker with caliber? I ask this espe-

cially with reference to vintage U.K. built rifles with 50

to 110 year old steel bbls.