Barrel steel, beyond stainless

[gunsandgunsmithing]

Can't seem to find it at the moment but I saw a huge broach pictured on one of the shooting forums within maybe the last several months to a year. I'd say broaching is the likely method for rifling the big barrels, though.

 

[davidjoe]

I came across ceramics being experimented with. I would have never though they would make good knife blades, either, but now it’s in F-1 brake discs, and in street use as an expensive option.

I also found this older release of an applicable liquid coating from a company called Otis Technology (which may have developed this on borrowed or grant money, that can influence real world viability) and I wonder if there is anything to this, as I have not heard of it.


The OTIS LifeLiner is a revolutionary new nano-ceramic micro composite that fuses to the inside of the rifle bore under the friction of the normal bullet firing cycle. Applied in a liquid form, it reconditions and protects against wear of all barrel bore surfaces; smoothbore, rifles, and pistols in 3 easy steps. During this process atomic sized particles embed in the metal surface and form a ceramic metal fusion that is nearly 800% harder than the best chromium plated barrels available today. Properly applied, it can prolong the bore-life of a barrel virtually indefinitely. It will actually redeposit a cermet coating on worn barrel surfaces. (A cermet is a composite material composed of ceramic (cer) and metallic (met) materials.)

Unlike topically applied friction reducing liquids, the nano-ceramic (subatomic) particles actually fuse to the metal barrel surface, filling in imperfections and surface irregularities. It will effectively redeposit a cermet coating on worn barrel surfaces, adding measurable microns of ceramic/metallic fusion material to the bore. This will increase back pressure while providing newly incredible consistency in Shot-to-Shot velocity.

The OTIS LifeLiner provides a ceramic coating that allows the bullet to glide down the barrel on an atoms-thin liner that protects the metal from contact with the bullet. Application is simple. Just load and fire.

The LIFELINER is available from you local dealer or on-line 24 hours per day at www.otisgun.com .

 

[gunsandgunsmithing]

I came across ceramics being experimented with. I would have never though they would make good knife blades, either, but now it’s in F-1 brake discs, and in street use as an expensive option.

I also found this older release of an applicable liquid coating from a company called Otis Technology (which may have developed this on borrowed or grant money, that can influence real world viability) and I wonder if there is anything to this, as I have not heard of it.


The OTIS LifeLiner is a revolutionary new nano-ceramic micro composite that fuses to the inside of the rifle bore under the friction of the normal bullet firing cycle. Applied in a liquid form, it reconditions and protects against wear of all barrel bore surfaces; smoothbore, rifles, and pistols in 3 easy steps. During this process atomic sized particles embed in the metal surface and form a ceramic metal fusion that is nearly 800% harder than the best chromium plated barrels available today. Properly applied, it can prolong the bore-life of a barrel virtually indefinitely. It will actually redeposit a cermet coating on worn barrel surfaces. (A cermet is a composite material composed of ceramic (cer) and metallic (met) materials.)

Unlike topically applied friction reducing liquids, the nano-ceramic (subatomic) particles actually fuse to the metal barrel surface, filling in imperfections and surface irregularities. It will effectively redeposit a cermet coating on worn barrel surfaces, adding measurable microns of ceramic/metallic fusion material to the bore. This will increase back pressure while providing newly incredible consistency in Shot-to-Shot velocity.

The OTIS LifeLiner provides a ceramic coating that allows the bullet to glide down the barrel on an atoms-thin liner that protects the metal from contact with the bullet. Application is simple. Just load and fire.

The LIFELINER is available from you local dealer or on-line 24 hours per day at www.otisgun.com .

Interesting and it might be great stuff. My concern may be unfounded but it would be in regard to such a hard surface treatment on a rifle barrel that physically expands, contracts and moves when fired.

 

[atblis]

There’s plenty off room for improvement simply using well known existing Stainless Steels. 17-4 is a notable improvement without resorting to any exotic coatings or materials. LW50 has proven this out, and now Bartlein is offering "400MODBB" for a cut rifling option. Both are likely their select 17-4 offerings.

 

[CharlieNC]

My current 6.5x47 barrel from CBI was nitrided by them and the borescope inspection looked pristine. While the black appearance has worn off inside the barrel, there is no sign of fire cracking but otherwise it's too early to judge longevity improvement. Supposedly the harder surface will deter wear.

 

[FrankG]

So, I've wondered about this very question - a lot.
On Lija's website, they say that CM is more resistant to abrasion and SS is more resistant to heat erosion.
They don't say, but my understanding is there is no difference in inherent accuracy between the two metals. Apparently SS can be machined more precisely => better chance of being more accurate.

The CM and SS do wear differently but there is no difference in the real world in terms of barrel life. I have and have seen too much data on ammunition pressure test and accuracy test barrels shot in controlled conditions etc...

There is also no difference in terms of accuracy either.

 

[ebb]

S Hall the Army had nothing to do with barrels not being chrome lined. That idiot Robert Mc Namara insisted that if Eugene Stoner thought that the barrels needed chrome lined he would have done it to the rifles he submitted to the Army for testing. The Army was over ruled by a paper pusher. Years later when asked Stoner said "I gave two rifles to the Army for testing, no way they were ready for combat.' Mc Namara had never even asked Stoner if they needed it or not. His arrogance got soldiers killed. he should have faced criminal charges.

 

[FrankG]

issues like in Vietnam when barrels were rusting out was because they weren’t chrome lined. Army probably went cheap with their steel and extra cheap with no lining. I’m not sure if modern barrels are lined or not.

Chrome lined barrels in the grand scheme of things doesn't do a whole lot for barrel life.

Also from an accuracy point of view you don't want a chrome plated bore. For one if the plating had issues with adhering to the surface it can crack/chip/flake out etc...prematurely and accuracy can suffer real early on in the barrel life.

Also plating can build up at the breech and muzzle end. This will cause tight and loose spots in the bore of the barrel and again having a negative effect on accuracy.

If chrome plating is suppose to help accuracy and or barrel life...then you have to ask this question. Why isn't it a called out spec. on ammunition pressure and accuracy test barrels for the Gov't? Simply put because it's a variable that you cannot necessarily control over the course of the life of the barrel. So they don't want it done.

Later, Frank
Bartlein Barrels

 

[FrankG]

Also think of chrome plating on a car bumper. Again if you don't take care of it...it will rust same as the bumper on the car as the bore of the barrel.

 

[FrankG]

My current 6.5x47 barrel from CBI was nitrided by them and the borescope inspection looked pristine. While the black appearance has worn off inside the barrel, there is no sign of fire cracking but otherwise it's too early to judge longevity improvement. Supposedly the harder surface will deter wear.

Nitriding from all the data I've been seeing doesn't guarantee anything.

For one a barrel can be left in the process too long...and actually work against you and shorten barrel life.

The ammunition makers that I've talked to and have had to use nitrided barrels during accuracy and pressure testing ammo don't like it. They say it causes too much issues in terms of pressure early on with the barrel and after about 250 rounds (like in a 300wm) the stuff is shot out in the throat area/first portion of the rifling.

Other testing has shown the nitrided barrels might not shoot as good as a untreated barrel from the get go. I've got data on 338 Lapua testing that shows this. For the first 1k rounds the untreated barrels shot better and met accuracy requirement. Yes it did help barrel life in this case with the 338 Lapua but the it only extended the barrel life 750ish to 1k round but you burned up a 1k rounds of ammo before the barrels shot as good as the untreated barrels did from the get go. So you blew (at the time) $6k worth of ammo before the barrels shot as good as the untreated barrels did. So what did you gain other then trigger time?

Also I'll say if you have poor quality steel and or if the button rifled barrels where not stress relieved properly or a combination of both....you nitride the barrel and the bore and groove dimensions can change on you.

Later, Frank
Bartlein Barrels

 

[FrankG]

FWTW - a long time ago I asked Boots Obermeyer "what is the difference" between SS and CM barrels". He told me that CM accuracy started to degrade with the first bullet and continued until..., where SS stayed at the same level of accuracy "until it didn't". He went on to say that could and often did, happen right in the middl

The CM and SS do wear differently but there is no difference in the real world in terms of barrel life. I have and have seen too much data on ammunition pressure test and accuracy test barrels shot in controlled conditions etc...

There is also no difference in terms of accuracy either.

I'll add this also....

From my understanding the ss will heat treat more uniformly vs cm steel. The larger the diameter of the steel as you get towards the center the ss will heat treat easier/more uniformly is what I understand.

If that's true though....then why isn't ss material spec'd over c.m. steel for 50cal and larger cannon type barrels?

That being said though...for the typical diameters we use steel for bolt gun barrels, gas gun barrels for like AR's, M14's etc.. and ammunition test barrels (which we've used up to 3" o.d. material for making ammunition test barrels) I haven't seen to ever be an issue.

 

[liljoe]

Where did I put my Blackstar barrels? Does anybody remember those?

Joe

 

[DocBII]

Where did I put my Blackstar barrels? Does anybody remember those?

Joe

Joe,

I've have/had two. One in .243 lasted 2.5k rounds, looked new with an N170 load @ 3050, burned up the last 1k rounds at 3150 and N-160. The other is a 300 WM I purchased second hand and an unknown round court, still shooting well with either Juggernauts or 210 class bullets.

I was told when I purchased the .243 barrel they were made from the LW50 steel.

HTH,
DocB

 

[CharlieNC]

Nitriding from all the data I've been seeing doesn't guarantee anything.

For one a barrel can be left in the process too long...and actually work against you and shorten barrel life.

The ammunition makers that I've talked to and have had to use nitrided barrels during accuracy and pressure testing ammo don't like it. They say it causes too much issues in terms of pressure early on with the barrel and after about 250 rounds (like in a 300wm) the stuff is shot out in the throat area/first portion of the rifling.

Other testing has shown the nitrided barrels might not shoot as good as a untreated barrel from the get go. I've got data on 338 Lapua testing that shows this. For the first 1k rounds the untreated barrels shot better and met accuracy requirement. Yes it did help barrel life in this case with the 338 Lapua but the it only extended the barrel life 750ish to 1k round but you burned up a 1k rounds of ammo before the barrels shot as good as the untreated barrels did from the get go. So you blew (at the time) $6k worth of ammo before the barrels shot as good as the untreated barrels did. So what did you gain other then trigger time?

Also I'll say if you have poor quality steel and or if the button rifled barrels where not stress relieved properly or a combination of both....you nitride the barrel and the bore and groove dimensions can change on you.

Later, Frank
Bartlein Barrels

How do you identify niriding is "shot out"? The loss of surface color is not indicative of the depth of hardness?

 

[ebb]

Frank I don't think that chrome plated barrels were intended to make the barrels last longer. they were to keep the chamber and bore from rusting and make the rifle more reliable in adverse conditions like swamps and jungles. It is my understanding that the Aasika rifles were the first production rifles that had this feature. Thanks for the great barrels you made for my 7mm, I really like your products.

 

[Bob3700]

How do you identify niriding is "shot out"? The loss of surface color is not indicative of the depth of hardness?

Our shooting team (prone iron sights) has been using nitride bbls for about 5 years now. It seems to take about 150-200 rds for the bbl to develop its best accuracy. They clean up easily n bbl life is definitely extended no matter the cartridge. We shoot 308, 6XC, 6.5x284, 243 , 6MM BRX. typically, 308 bbls are still shooting cleans at 5500-6000 rds. The throats of the 6.5x284 look smooth at 800-900 rds.
The only draw back is there are no bbl setbacks Or crown touch ups. The steel is too hard. Our group has had excellent results with the salt bath nitride bbls.

 

[3Sigma]

Interesting and it might be great stuff. My concern may be unfounded but it would be in regard to such a hard surface treatment on a rifle barrel that physically expands, contracts and moves when fired.

Anyone who's done real design and development with ceramics knows that material boundaries are key failure points.

The OTIS "ceramic" sounds like nothing more than ceramic car coating applied to rifle barrels. Nothing will stand up to 2500°F and 65,000 psi that is only microns thick.

Ceramics would make great rifle barrels until they fracture due to pressure cycle fatigue. Not an intrinsically safe setup.

The company that can make a TTZ zirconia lined barrel with a steel outer shell and chamber would own the market.

 

[3Sigma]

If that's true though....then why isn't ss material spec'd over c.m. steel for 50cal and larger cannon type barrels?

I'd have to get into my design tables, but my assumption is surface harness (cannon barrels) and service temperature (machine gun barrels). In continuous service, 400 series is only good to around 1300°F (700°C) give or take a few 100 degrees, but chrome moly based alloys can be made for higher temperature service. I assume most the wear and tear on a .50 caliber M2 barrel is at high rates of fire and high temperatures.

 

[FrankG]

How do you identify niriding is "shot out"? The loss of surface color is not indicative of the depth of hardness?

You can physically see the difference in a sectioned barrel.

Also the depth of the hardness if you want to say it that way…from what I under stand is suppose to be only like a couple of tenth’s. Not a even a .001” of an inch.

 

[FrankG]

I'd have to get into my design tables, but my assumption is surface harness (cannon barrels) and service temperature (machine gun barrels). In continuous service, 400 series is only good to around 1300°F (700°C) give or take a few 100 degrees, but chrome moly based alloys can be made for higher temperature service. I assume most the wear and tear on a .50 caliber M2 barrel is at high rates of fire and high temperatures.

The actual M2 barrels or should I say current spec is the breech end of the rifling (I think it is like the first 8” or 10” of the rifling) is actually a stellite liner. The liner gets rifled by itself and then it is inserted into the breech end of the barrel and your suppose to line up the rifling. Keep in mind the tolerance of the groove width on 50bmg barrels is .010”.

The stellite takes the heat much better. We’ve rifled stellite liners. Not the nicest stuff to work with.

So if you will the bore of the 50bmg barrel is a two piece set up.