Black powder rifles

Quote:

Originally Posted by GrantRCanada

IIRC, that was mentioned on one of the other threads I referred to, but a subsequent contribution from a metallurgist indicated that, in the industry, the term "seamless tubing" can simply mean that the product is formed with a seam, but that it then undergoes a further rolling/burnishing process (internally and externally) to eliminate any roughness or detectable extra thickness along the seam line .... :(

That's a load of bunk.

From the DG website:

Quote:

The seamless tempered barrels are made of high-carbon steel (BS970 no. 080M40) and the breeches are threaded.

BS970 no. 080M40 is actually a medium carbon steel (not high carbon like DG states) - it's type 40 carbon with a En number of 8. It IS heat treatable. Typical tensile strength is 700-850 N/mm. In other words, with the proper heat treatment, you can get about 110,000 psi of pressure resistance out of a tube made of this material. Granted, the Indian copies are not designed, treated or proofed for anything even close to that pressure.

There are three classes of manufactured tubing: seamless, as-welded, and drawn-over-mandrel (DOM).

Seamless tubing is produced via extrusion while drawn-over-mandrel tubing is made from cold-drawn electrical-resistance-welded tube that is drawn through a die and over a mandrel to create such characteristics as dependable weld integrity, dimensional accuracy, and high-grade surface finish.

Here's a pretty good primer on how seamless tubing is made:
Making seamless tubing with a floating mandrel mill

Anyone telling you seamless tubing has a welded seam does not understand the first thing about engineering or materials science.