Stellite Liners?

O

Old Gunner

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Recent threads on setting barrels back when the throat is eroded got me thinking of the Stellite liners used in some MG barrels.
I also recently found photos of a 1895 Mauser than had been rechambered to 7.62 NATO by using a similar insert to allow the shorter chambering in the original barrel. This insert had rifling cut in the insert as well as the bore, so I guess it was originally a 7mm rebored to .308.

Some .50 BMG barrels made these days also have the origin of rifling as part of the stellite liner. I think these are cut seperately and matched to the rifling in the bore during insertion.

I wonder if a stellite liner would be a useful addition to a target grade barrel.

Any thoughts on this?
 
Stellite liners aren't pushed in and then machined. Thery are cast-in. Word is you can't machine it. I have no personal experience. When salvaging a demilled 50 BMG barrel I just cut off the 11" which has the stellite lining.
 
Stellite liners...

most commonly encountered in U.S. made machinegun barrels, are not 'cast in place'. They are finish-machined (to include rifling), then inserted into the breech end of the barrel - the junction line between the front end of the liner and the bore of the barrel itself is clearly visible when inspected from the breech-end of the finished barrel. The stellite liner is used in machinegun barrels due to the material's much greater resistance to high temperature erosion as compared to barrel steel. It does nothing positive to improve the inherent accuracy of the finished barrel (except to extend the serviceable life of the barrel in use), and, since rifles intended for extreme accuracy applications are not, as a rule, shot very rapidly for extended periods, there is no point in going to the trouble (and considerable expense)of a stellite liner.
mhb - Mike
 
"These alloys can not be softened by heat treatment and must be cast or ground to shape. The room temperature hardness of cast nonferrous alloys is lower than for high speed steel, but the hardness and wear resistance is retained to a higher temperature. The alloys are generally marketed under trade names such as Stellite, Crobalt, and Tantung." Page 998, Machinery's Handbook #24.
I was told, 40 years ago at a US Army Ordnance Facility, that Stellite liners in .50 BMG barrels were cast in place over a precision core. I have heard this fact many times since. This is the first time I have ever heard it contradicted.
 
I googled "Stellite liners" and currently it seems that the liners are cast, then ground to size and pressed in. Then honed and button rifled in the bore.
 
The most likely article that comes up on a search...

That is, one of the first and probably the source of the information you quoted is one concerning the making of M2 barrels by Sabre Defense Industries. This gets several hits, first as printed in American Machinist.
Reading the article closely, I think you will agree that Sabre must, indeed, be pressing-in a completely finished liner, as the article refers specifically to measures taken to insure that the rifling in the (finished) liner is accurately indexed with that in the barrel itself. The article does not specify how the rifling is formed in the liner, though it is certainly possible that it is formed in the casting process and finished by other means.
FWIW, I was told a great many things by various folks during my 24 years and a bit in the Army - some of them gave the straight skinny, and some told more than they knew.
mhb - Mike
 
Roger that! I looked over the google articles and they weren't real specific. Of course, nobody was button rifling or swaging rifling during WWII, as far as I know. New methods, who knows? They could be using EDM for all I know.
 
Well...

IIRC, Mike Walker is credited with helping to develop button rifling (in the U.S.) while working for Remington during WW2. Whether any barrels were made by that method under wartime contract, I don't know, but Remington did button-rifle barrels made just after the war ended, and subsequently for some years. Hammer forging was certainly known around the same time, and I seem to recall that the Germans actually did make some military barrel by that method - which they later perfected and still use.
mhb - Mike
 
I don't think they were capable of EDM machining MG rifling at that time. Probably not cost effective at this time either.
Butch
 
Probably not...

I've only seen one attempt at EDM rifling in exotic materials (the time we tried to rifle barrel blanks of Rhenium and Tantalum alloys - both of which sneered at anything we could do by way of cut rifling), and the results were NOT pretty, though they apparently were sufficient to conduct the intended tests of durability in extended automatic fire, where accuracy, per-se, was not a consideration - and as it was a government project, cost was not a consideration. The blanks themselves cost about $2500 each, IIRC.
mhb - Mike
 
Memories from my "salad days".

papapaul said:
Stellite liners aren't pushed in and then machined. Thery are cast-in. Word is you can't machine it. I have no personal experience. When salvaging a demilled 50 BMG barrel I just cut off the 11" which has the stellite lining.
Click to expand...

As some one else said,that's not true!
I remember that the Westinghouse Specialty Metals plant cast these out of Stellite,and shipped them to our customer that way.This was in the very early 1960's.
We had a lost-wax casting facility and cast many millions of small turbine blades,magnets,etc.
I doubt if they were machined by normal cutting tools.They were too hard.
I worked in the Spectrographic lab at the time and we did the chemical analyses on all metals produced at the plant.
To prepare the sample for X-Ray Fluorescence or Point-to-plane Spark spectrography,we had to sand the surface of the sample disk flat.
With Stellite,you could sand about one sample per 6" X 60" aluminum oxide belt.
We also made many exotic alloys that were Westinghouse inventions - Discaloy,Refractaloy,Nivco,etc. We had one alloy,K42B,that had to used as-cast.You couldn't even grind it.
We also cast triggers,hammers,etc. for the M16's,on a contract from General Motors,in the early 60's.
In 1972,we got out of the metals business and started making Nuclear Grade tubing. If you wanted to make gun barrels,you could do it with a pilger mill.
The fuel clad tubing had to be held and inspected to 4 decimal points,with very tight tolerances.
The swagers we had,had difficulty holding those tolerances.
 
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Fuel clad tubing???

relodr36 said:
.
In 1972,we got out of the metals business and started making Nuclear Grade tubing. The fuel clad tubing had to be held and inspected to 4 decimal points,with very tight tolerances.
The swagers we had,had difficulty holding those tolerances.
Click to expand...

Are you referring to Zircalloy?

Lou Baccino
 
chino69 said:
Are you referring to Zircalloy?

Lou Baccino
Click to expand...

Yes,Zirc 4.
When I retired in 1994,they were also using ZIRLO,a new alloy produced by the Western Zirc division.It was touted as being more corrosion resistant and able to stand higher burn-ups.
 
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