Nitride the barrel

[yorketransport]

Try working up new loads. You may be able to increase the powder charges over what was previously your max. If the nitride reduces friction and pressures, you may just need to push the pressures back up a little to regain the velocity.

Andrew

[Aircraftmech76]

Ring31, what was your metal prep process prior to nitriding with H&M? Did you bead blast? I'm digging the flatness of the finish.

Kevin

[358Hammer]

A drop in pressure as Andrew indicated would require more powder like back in the day when many of us used various lubricity products on our bullets.

I haven't seen a drop in velocity in 9 barrels so would be curious to see what the bore pins out at.

We are all learning about the various Nitriding properties and vendors so the more information that is put out there the more we all benefit.

Currently I am leaving a Nitrided stainless barrel on a untreated stainless action with stainless barrel nut in a well padded canvas case. The past 3 months it has spent weeks in my 4 X 4 Van then into the house and back out into the van. The nut has spots of surface rust. Nothing else yet. I did hunt a couple days in the rain and nothing has affected the gun yet.

I am now at 900 rounds on my 6.5 WSM shooting 130gr Accubonds at over 3000fps from my 19"Striker barrel and the accuracy is still amazing.

Neal

[Aircraftmech76]

My favorite option is to do bolt and action with the bearing/spring_ It is as smooth on one could possibly want it.

Neal


When you say bolt, do you mean the whole bolt to include all baffles and bolthead minus the springs? Just wondering how far you've taken to the bolt to.

Thanks,

Kevin

[358Hammer]

Kevin

I have done nothing on the bolt and only used the bearing and perch after market setup at the back of the bolt. To

Bolthead, baffle,bolt body, handle and bolt assembly retaining nut at the rear of the bolt, all being nitrided.


To date after 5 months of riding in my van and heating up nearly every day when the van is driven I have yet to have anything Nitided rust. In my salt water and very humid climate at times, regular stainless steel has surface rust that must be dealt with regularly.

Neal

[Aircraftmech76]

So you will be nitriding everything? Is that what I glean from your second paragraph? Where are you sending your stuff in to be nitrided these days?

[358Hammer]

Actually my go to hunters are Nitrided and done.

I have everything done that I will ever Nitride! Nitriding stainless pretty much assures I will never wear out the item nor will it ever corrode in any way.
I am a bit concerned however where the cost has been going for the very simple Nitriding process. When I originally made the first post on Nitriding some years back I could have a very complete ready to shoot without issue finished product for $40.(barrel)-$80. barreled Action) with a .003-.004 Nitride penetration. Now others have started handling the process (middle man) with much more financial burden and some are treating at a lessor heat and a .001-.002 penetration using other venders.

I like the added bullet speed and the wear charactoristics particularly with high volume shooters. Highly recommend the process and to date have found NO down side.

Neal

[Aircraftmech76]

So who are you now using for your nitriding needs? How much do they want to do a whole weapon? How much prep and cleanup is there to do?

Kevin

[macds]

Gents,

I am new to the site here, and have been doing WAY too much reading :)
Anyways, I am a precision toolmaker, and have TONS of experience with nitriding. I have a few questions about the nitriding you guys are having done on your barrels. Often what I see with nitriding is that it actually accumulates a "film" on the surface of your part. Typically causes a growth of .0002 per side (would be .0004 on a diameter). I wondering if this has an effect of velocities? Also, with the heating required to apply the nitriding, you typically see some warpage in the part. I would think in a long hollow piece like a gun barrel, you should see a fair bit of warpage (stress relief). Can anybody verify this for me?
Thinking the a different (but expensive) option would be Ion nitriding (which is gas vapour at high heat), or something called Alcrona coating (this stuff is upward of 100 HrC, and has a friction co-effiecient lower than teflon, and is less prone to chipping from heat cycling).

Anyone have some thoughts on this?

Best Regards,

Stu

[Sundo]

I wonder if too little friction could be causing loss of velocity. A previous post mentions the Alcrona process produces a surface with less friction than Teflon. Could too little friction cause the bullet the start moving before enough pressure has built up for a complete burn to full velocity?

I recall reading that moly coated (for less friction) bullets require extra powder for this reason. I suspect a friction reducing treatment could have a similar effect.

[Dennis]

Stu, welcome aboard!

I am hoping several will answer your questions. Should be interesting!

[358Hammer]

Ferritic nitrocarburizing
Not to be confused with Carbonitriding.
Ferritic nitrocarburizing is a range of case hardening processes that diffuse nitrogen and carbon into ferrous metals at sub-critical temperatures. The processing temperature ranges from 525 °C (977 °F) to 625 °C (1,157 °F), but usually occurs at 565 °C (1,049 °F). At this temperature steels and other ferrous alloys are still in a ferritic phase, which is advantageous compared to other case hardening processes that occur in the austentic phase.[1] There are four main classes of ferritic nitrocarburizing: gaseous, salt bath, ion or plasma, and fluidized-bed.[2]

The process is used to improve three main surface integrity aspects:

scuffing resistance
fatigue properties
corrosion resistance
It has the added advantage of inducing little shape distortion during the hardening process. This is because of the low processing temperature, which reduces thermal shocks and avoids phase transitions in steel.[3] ( Wikipedia) I did have to re-bed a stock that had been bedded prior to Nitriding as typically actions are not stress relieved and this one would bolt up it was still snug in the wrong places. I intenionally did the afore mentioned so that I could readily check for metal movement.

In a statement regarding warp I have to say None observed I will say that none stress relieved metal prior to heat or stress relieving will cause a metal movement. Warp- well all nine barrels shoot extremely well so warp implies something bad and I have nothing but praise for the process..

The last company to send in my barrels for the process was Benchmark barrels.

Neal

[Dennis]

???

[macds]

What material specifically is being used for the match grade barrels? I know you can get stainless, but what grade of stainless, what exact steel?
Just trying to understand how more stress relief is not being seen. Even in a pre stress relieved piece, at those temperatures (its hot enough to move stuff) you will see permanent geometric changes. Think about what your barrel does when shooting a lot with out cool off time.
It would be REALLY interesting to put a new barrel on a test bed between centres and mark runout before and after nitride. The best I would think would be Ion, I dont think id go salt bath myself....
Does anybody have an opinion on nitride as a friction reducer? It reducing friction good or bad? Less friction means less heat and less wear, but is there something ballistically the requires friction, like proper bite in the lands?

Just thinking...

Stu

[sha-ul]

It reducing friction good or bad? Less friction means less heat and less wear, but is there something ballistically the requires friction, like proper bite in the lands?
Rifling engagement would be more of a swaged mechanical fit not frictional, it distorts the softer copper whereas a patched ball in a muzzle loader would rely more on friction from the patch to the ball.

[macds]

Same thing no?

[earl39]

Same thing no?


It is different. Think of it as your hand in a glove trying to hold a round pipe. That would be like a round ball in a patch in a muzzle loader barrel, it all relies on friction between the patch and ball with the patch filling the grooves and protecting the ball from the lands. The bullet and rifling would be like a bolt and nut. Think of a tight fitting nut with no lube on it then put oil on the threads and try to spin the nut again. Much easier. In a barrel you need to increase power to get pressure back to get speed back up to where it was without the Nitride. Moly, as stated earlier, does the same thing without the added wear protection due to harder metal. It is a matter of are you willing to spend more on powder in the life of the barrel for longer barrel life, corrosion resistance, reduced friction induced heat, greater resistance to throat erosion and heat checking and i am sure i am leaving some things out.

[macds]

Thanks earl, thats exactly what I was looking for there...
So if your already at max case load before nitride, youll actually see a performance drop due to the nitride, from what ive gathered?

Thanks

Stu

[yorketransport]

Thanks earl, thats exactly what I was looking for there...
So if your already at max case load before nitride, youll actually see a performance drop due to the nitride, from what ive gathered?

Thanks

Stu


Yes, but you can regain the performance by bringing the pressures back up. Since the reduced friction also reduces the pressures, you can work up new loads and increase the charge weights. So, you can operate at the same pressures, it just takes more powder to reach those pressures in the treated barrel.

Andrew

[earl39]

Thanks earl, thats exactly what I was looking for there...
So if your already at max case load before nitride, youll actually see a performance drop due to the nitride, from what ive gathered?

Thanks

Stu


Yes, but you can regain the performance by bringing the pressures back up. Since the reduced friction also reduces the pressures, you can work up new loads and increase the charge weights. So, you can operate at the same pressures, it just takes more powder to reach those pressures in the treated barrel.

Andrew


Or you can go to a slightly faster burn rate powder. What it all amounts to is wear resistance is greater so you get more barrel life. Take the 308win. Average target life is 2500-3500 rounds (some barrels last longer). Nitriding the barrel will increase the life maybe even double it. Compare a new barrel (350-500 dollars) to having your barrel nitrided (100 bucks) and you can see the savings adding up. I haven't tried to run the numbers but just saying it takes a full 8 pound keg of powder during the life of the barrel to get pressures back up it would be like getting two barrels for 200 bucks more than the first barrel. You have the barrel life of two barrels for the price of 1 1/2 barrels which means more shooting with the same barrel and less load testing needed so more true competition rounds before needing to change barrels and start all over again. With a hunting barrel you will never have to replace it unless it is a dogtown barrel and it is really abused.
Added after thought.
It was mentioned that the heat might stress relive the barrel even more than it was relived at the factory causing some warp-age. As long as the crown is good any slight warp-age should not cause a problem with point of impact. Point of aim might be a problem due to warp-age though. A warped barrel may shoot 10 foot to the left for example but if the crown is good it should be consistent. You would just need enough adjustment in your sights to get POA and POI together. This would be an extreme example of course as it would be about 114.6 moa. Most barrels warp-age would never be noticed due to change incurred when taking the barrel off and putting it back in the receiver might be 0-2 moa.
A barrel not properly stress relived will walk that much and sometimes more just from heat of being fired.

I hope everyone understands that my talking parrot told me what to type and being Christmas Eve i was obliged to do what was asked of me.

Merry Christmas All