Barrel metal

[scpaul]

I'm in the process of building a slightly+ overbore wildcat (7mm Valkyrie). Which barrel metal (stainless or one of the regular barrel steels) would give me the best barrel life? Other than sighting I probably won't be shooting over 2-3 times a day. I plan to be using something like IMR 7828 and 150-168 +- gr. bullets, probably coated with something like Lubalox (winchester). The next barrel (not too long in future, I hope) will probably be in the 29-30 in. range. Thanks, have a good one, Paul

 

[GrocMax]

It always puzzled me that barrel steel was one of the very first specifically defined alloys in both 'carbon' and 'stainless' and hasn't changed much in 100 years.

There are two things that have changed GREATLY in mfg in those 100 years,

#1 Electronics.

#2 Material science.

Engineering hasn't changed. Methodology has a bit. Quality control methods have (see #1). Materials have. Why are we using the same old materials and the same old methods? Is it truly optimal? Were firearms on the forefront, and the catalyst of technological change, and therefore we have seen the most we can?



Yet the same old, same old applies.

 

[akajun]

Because its kind of hard to beat what works. Barrel steel is a balance of machiniability and durability. I know that other materials have been used, at great expense, such as stelite, which lasted much longer but tripled the cost of the barrels. Now with Smith using a chemical etching process to make barrels, maybe that cost could come down some, but stelite itself is not cheap.
I know in the early days of smokeless, that barrels were made from simple mild steel, or lower grades of steel, which worked fine for blackpowder but wore out fast with smokeless. This lead to other types of barrel steel tried, some worked, some didn't. 4140 was picked up pretty quickly, as it's been around for a very long time. Winchester marketed their "nickel steel" barrels, I dont know what the number of those were but were regarded well.
Kind of hard to beat good old 416 stainless or 4140cm. If it were me, Id have whatever barrel I got melonited after break in, it seems to increase life without harming accuracy.

 

[scpaul]

I appreciate both of your responses. I'm looking to find the preferance by shooters and wildcatters that have more experiance than me in selecting between stainless and CM for an overbored wildcat that isn't as extreme as some I've seen. I'm familiar with cryo treatment but not with Melonite other than hearing others talking about it. This is a work in progress, I'm at the point of rechambering the original factory 7mm barrel. I'm going to do most of the testing and some load workup with this barrel to save some wear on the custom one. At this point I'm working with a 24 in. barrel and expect the new one to be somewhere close to 30 inchs. I'm also looking at a barrel taper some lighter than a straight bull barrel since carrying the rifle isn't one of the major concernes. Any advice from more experianced shooters/wildcatters will be greatly appreciated. Thanks again akajun and GrocMax, Have a good one, Paul

 

[scpaul]

Almost 200 views and other than 416 stainless and 4140 chrome moly, no one else has an opinion? There are other metals/alloys available, isn't there ? If not, tell me and cure my ignorance! Ok, in ya'lls opinion who makes the best/most durable barrels for overbored wildcats ( not extreme )? And What type of treatment is Melonite ( ignorant again? ) Thanks, Paul

 

[carlsbad]

I haven't seen anybody making a convincing case that SS over CrMo or vice versa is better. Based on the amount of literature out there, I'd say they are pretty darn close to equal.

BTW 416 and 4140 are generally the ss and CrMo that is used.

 

[Ggmac]

41v50 it is required for military . One US test revealed 3x the life of either 416 SS or 4140 Cm, using 300 win mag .

 

[butchlambert]

Gary, I respect your knowledge. Could you let us know where you got your information?

 

[Robert]

I haven't seen anybody making a convincing case that SS over CrMo or vice versa is better. Based on the amount of literature out there, I'd say they are pretty darn close to equal.

BTW 416 and 4140 are generally the ss and CrMo that is used.

Just to note, some characteristics of interest:

-The 416, supplied in annealed condition, is about:
Brinell Hardness : 170-175
Rm: 630-650MPa
Modulus of Elasticity: 200Gpa.
Thermal conductivity: 25W/m-k

-While the 420 is:
Brinell Hardness 205
Rm: 725Mpa
Modulus of Elasticity: 200GPa.
Thermal conductivity: 25W/m-k

-The 4140 is:
Brinnell hardness: 225 to 241
Rm: 1000MPa
Modulus of elasticity: 205GPa
Thermal conductivity: 43W/m-k

The 420 is the one used by Lothar Walthr

R.G.C

 

[Ggmac]

Butch , I have been looking thru my ref books and have not found the test I reported . I will keep looking . It's a pain when you can't find what you've read . Still looking .
A simple Google search pulls up a lot related to the military requirements.
I have been doing the barrel and chamber work for a start up rifle manufacturing company and we tested the barrel life for accuracy , 41v50 vs 416ss. And 4140 . The accuracy gradually dropped of after 1500 rds with the 416ss and 4140 .we used a hot little case ,22-250 . We didn't use a large case due to powder shortages. The 41v50 is still going at 2000+ .
I will still look for the articles
Best regards, Gary

 

[watercam]

I think Robert answered the question fairly well.

 

[Robert]

I think Robert answered the question fairly well.

It is my belief that the mechanical erosion does more harm than heat erosion on barrel throats.
Carbon particles and primer residues propulsed by 4000bar of pressure certainly have a powerful blasting effect. I recommend when depriming cases, to recover some primer residue jn the pockets and check its lapping capabilities……
And when I consider water/abrasive jet process cut the harder metals like butter at only 400bar pressure I do wonder on the fact firing generates 10 times the water jet pressure !!.

Superficially hardening the metal has a limited effect as the undercoats remain soft and are affected by abrasion as soon as the treated coat is gone or simply attacked. The undercoat gives anyway no better support to the surface coat…

Therefore, the harder the base metal, the better it resist abrasion.

And, if the heat is considered as the most important abrasion factor, I think the heat conductivity coefficient should be of some consideration.

My point, FWIW

R.G.C

 

[sdean]

Gary who makes barrels out of 41v50

 

[Ggmac]

Sdean , I sent you a PM.
I have been using the barrels for a couple of years now . Over 53 and counting , not all were 41v50 .
The 41v50 barrels I used were 338 , 308 , 224 and I think a 6.5 ( not sure I would need to check records ) .
Good luck , Gary

 

[scpaul]

Thanks everyone, I'm getting a lot of usable info. for the near future when I can get (read afford) the final barrel for this project. Would chryo-treatment be any improvement if used in conjunction with a Mellonite treatment, and any idea how expensive the treatments are and the order that they should applied? Thanks to everyone again, Paul

 

[Robert]

Thanks everyone, I'm getting a lot of usable info. for the near future when I can get (read afford) the final barrel for this project. Would chryo-treatment be any improvement if used in conjunction with a Mellonite treatment, and any idea how expensive the treatments are and the order that they should applied? Thanks to everyone again, Paul

Paul,
This post wil most certainly provoke a chain reaction but I would never have a good barrel be heated at the temperatures needed for QPQ (!Melonite) process (550°C mini).

Considering the care barrelmakers takes in stress-relieving their gppd
products, I wonder on how the Quench-Polish-Quench is performed safely for the barrel Integrity?

Also, as I consider mechanical erosion as the primary wear factor, once the thin hardened layer is gone through, the remaining soft undercoat is left bare for the aggression.

.Now, it seem you mention cryogenisation? Cryo only purpose in metallurgy is to remove the last traces of Austenite after heat treatment. Applied to annealed 416, already Martensitic in structure, I really do not see what this treatment come to do for SS barrels?

R.G.C

Then again,,better to go first to the harder steel who will not from start show this substrate problem.
Again, my point only, FWIW

 

[butchlambert]

Forget the Cryo and do the melonite.

 

[Ggmac]

Scpaul , I sent you a PM. Feel free to PM or email Ggmac5@aol.com
Gary