Probably, but not in any practical sort of way to be concerned about. Most people can't shoot enough, or hot enough loads to cause any form of appreciable erosion due to firing. And what does get caused, will certainly take many thousands of rounds to get there to the point accuracy is noticeably degraded.
The metal is probably a little softer and bendier too, but again, probably not materially meaningful that way. All will engrave just fine. The bigger risk to all of them is abuse or neglect. Be a little bit extra careful with your cleaning rods (be sure you are using a bore guide) and you should be fine though. For gosh sakes, no aluminum or fiberglass rods! Those can be pretty abrasive to an unprotected crown.
4150 heat treated for barrels is designed to be wear resistent - it is used for machine gun barrels - so I'm going to go out in a limb and say that it will outlast 12L14, a steel designed for screws. Having said that, in a discussion on barrel steels over on ALR folks elicited the information that the late Roger Fisher had managed to put 40,000 rounds through a 12L14 barrel, and it was still going. I think he had roughed it up with sandpaper at one point to restore accuracy (no, I don't know what he was talking about) but the lands and grooves were still there.
I have to assume you have some 12L14 to machine yourself?
I have made many smooth bore 'toy' barrels. Just a plain rod with a threaded breach plug, strapped to a 'carriage' or even 2 x 4. Drill a hole for cannon fuse and BAM- instant fun!! Brass, bronze, stainless, 12L14, all sorts of stuff.
I never saw anything make real 'wear issues'. Lead balls, steel dowel rods, stupid overcharges, all manner of stuff that shall remain unmentioned.
The corrosion was the only real factor in anything. I have put 12L14 to some bad pressures, I never saw or measured any deformation.
I'm comfortable using it, but personally I wouldn't expect to see it in a purchased ML. It is easy to machine but I don't see any barrel manufacturers using it. Biggest problem is keeping the bore concetric to the OD, If you drill from each end you WILL get a mismatch; unless you have gun drilling machine...
Nothing here to imply you are actually going to rifle cut it.
I found this searching the web. It looks like several barrel makers use 12L14. I'm a machinist and 12L14 is leaded steel and is easy to machine, but it is pretty soft. I just got a Colerain barrel made out of 12L14 and I shoot a lot. So I was just wondering what life expectancy I could get out of it compared to a Green Mountain barrel made out of 1137.
Longhammock - 12L14
Getz - 12L14
Rice - 12L14
Ed Rayl - 8620
Green Mountain - 1137
Flintlock Construction, Inc. (Charlie Burton) - 12L14
Isn't the hardness of the barrel related to how it was tempered? i.e. a 4150 barrel can have the same hardness as a 12L14 barrel depending on the temper. I believe a more important issue is the toughness and corrosion resistance of a steel. With BP, from what I've read, corrosion resistance seems to be of high importance.
For what it's worth, ASTM 4150 is a chrome-moly steel which can be hardened.
Even in its annealed state (HB 197) it is considerably stronger (UTS 106 K psi) than any of the low carbon steels including 12L14 (60K psi).
Like all of the low alloy steels, 4150's resistance to corrosion isn't much different than the low carbon steels but it is about 3 times more difficult to machine than the leaded 12L14 steel.
Whether the additional strength of 4150 is needed for a black powder muzzleloader is needed is a bone of contention that will never be answered to everyone's satisfaction but, based on the history of tens of thousands of muzzleloaders successfully using 12L15 without any problems I will happily continue to shoot all of my ML's with their Colrain, Rice and Getz barrels.
I have bilt many CVA and traditions kit guns for Amish hunters who just don't understand cleaning the guns! One year, need lapped, two years relaped, three years refreshed. It is the cleaning and storing that determine barrel life not number of rounds! I have over 20,000 rounds through my Douglas barrel made of 12l14 with it good for the rest of my life as long as properly cared for! :idunno: :idunno: