lets talk about barrel life...

[jimmykan]

Are there any inside linings, like chrome, that can extend barrel life?

I now use stainless on everything even hunting rifles and if your after that black finish you can have a stainless barrel melonited.

Melonite a.k.a. Nitride or QPQ is a surface treatment that hardens the outer skin of a steel object, and turns it black.

I just measured the hardness of two barrels I have on hand using a Starrett 3811A portable hardness tester:

A Faxon QPQ Nitrided 4150 barrel: 3-point average hardness was 56.3 HRC

A Bartlein stainless 416R barrel blank: 3-point average hardness was 30.8 HRC.

I don't have any nitrided stainless barrels on hand, but I would imagine that the Bartlein barrel's surface hardness could be increased to 55 HRC by nitriding/Meloniting.

The nitride treatment penetrates just a few thousandths into the steel surface, I would not think it would be more than 0.005" or about the difference in height between a rifling groove and land, but that would be deep enough to increase the life of the throat.

Anyone have experience with nitrided stainless match barrels? How much longer do they last?

https://faxonfirearms.com/blog/frequenty-asked-questions-nitride-vs-chrome-lined/

[russ69]

...I don't have any nitrided stainless barrels on hand, but I would imagine that the Bartlein barrel's surface hardness could be increased to 55 HRC by nitriding/Meloniting....

I have a barrel that has a melonite finished. The flash hider threads were over size after the melonite finish was applied and my hardened die will not cut the threads. It's pretty hard.

[ar15barrels]

I have a barrel that has a melonite finished. The flash hider threads were over size after the melonite finish was applied and my hardened die will not cut the threads. It's pretty hard.

Lap the brake on with 600 grit clover.
The clover will cut the clearance into the brake.

[LynnJr]

My old shooting buddy John Pretty Gun Crawford used a melonited 6 Grenfell to win the NBRSA 600 Yard Heavygun title in 2011 or 2012 I can't remember which.
For those that like hotrod engines it's the same process as a nitrided crankshaft.

[russ69]

Lap the brake on with 600 grit clover.
The clover will cut the clearance into the brake.

Thanx, I just so happen to have some of that in the toolbox. I thought with an adjustable die I could ease into it and get it cutting but no joy. I'm about 3 threads from being fully seated. I'll give it a try, thanx.

[Mustang]

Thanx, I just so happen to have some of that in the toolbox. I thought with an adjustable die I could ease into it and get it cutting but no joy. I'm about 3 threads from being fully seated. I'll give it a try, thanx.

Any way to avoid this? Can the threads be covered during the process?

[jimmykan]

Any way to avoid this? Can the threads be covered during the process?

No, the muzzle threads with lapping compound on them are what's doing the cutting.

[ar15barrels]

Any way to avoid this? Can the threads be covered during the process?

Ask your plater if he can mask an area of the part to NOT be nitrided while the rest of the part is being processed.

[ar15barrels]

Thanx, I just so happen to have some of that in the toolbox.

After barrels come back from Melonite, I usually have to lap them into the reciever with clover to get them back together.

[Mustang]

No, the muzzle threads with lapping compound on them are what's doing the cutting.

I understand that. What I meant was could the threads be covered before the plating process so none of the melonite was deposited onto the threads.

[Dogbite]

double post

[Dogbite]

Basic explanation -

Gas nitriding - 900F to around 1250F - Case hardness depth dependent upon hours of saturation. Best for medium and high carbon steels .002" up to .024" penetration on 4140 though 4340 typical barrel materials. Figure 25+ hours for .024" case depth. Must be in an atmosphere that circulates the air well. Base material growth is around .0005".
55-57 HRC can be achieved easily.

Melonite - Liquid nitriding. Faster penetration, use to use Cyanide + other chemicals - Not legal in Most of the USA that I Know of. I don't know what they use now. For the boar of a rifle, a better process - Same saturation depth which is dependent upon saturation time.

Both processes are wonderful for medium grade carbon steels.

You can Nitride anything but that does not meant that it penetrates. Stainless barrels will only get a .001" to .002"(NO CASE DEPTH) of penetration if that. I could be wrong and I will get a lot of flak from this but until a used barrel is cut in half and I can see the results though a microscope, I will stand by what I just typed.

Both processes are a ***** to clean up & lap afterwards.

[ar15barrels]

Melonite - Liquid nitriding.
I don't know what they use now.

Cyanide free heat treating salts.

[Dogbite]

Cyanide free heat treating salts.

LOLOLOLOL

[russ69]

I have a barrel that has a melonite finished. The flash hider threads were over size after the melonite finish was applied and my hardened die will not cut the threads. It's pretty hard.

Lap the brake on with 600 grit clover.
The clover will cut the clearance into the brake.

Old thread and a little off topic but thanx Randall, the Clover did the job. I just got around to it. Easy peasy.