Nitrate vs nitride?

Nitride: A nitride is a compound of nitrogen.
Nitrate: A polyatomic ion. Nitrate salts are found naturally. As in Sodium Nitrate.
Suspect the marketers are using 'nitrate' incorrectly. Nitrides are used for coatings. Nitrates to blow stuff up and preserve stuff.

When describing what about a barrel? Metal alloy? Corrosion/rust agents?

Google or Yahoo are your friends:

Titanium nitride is usually used as a coating to increase resistance to wear and corrosion.

Titanium nitride:
https://en.wikipedia.org/wiki/Titanium_nitride

A nitrate is an ion of nitrogen and O3. The "ate" typically means a compound of oxygen.

I don't think there is such a thing as titanium nitrate.

Nitrate:
https://en.wikipedia.org/wiki/Nitrate

Titanium Nitrate used in a barrel description? Can you show me that? This is an unstable compound, a stong oxidizer, among other things should not be described as associated with firearm barrels. Must be a misunderstanding.

Melonite and Tenifer are nitriding methods, more well known for use on Glocks, HK and S&W handguns for example. Tenifer and Melonite are heat treatment processes that diffuse nitrogen into the surface layer of the steel to harden it and make it corrosion resistant. These days it gets a lot of hype as a superior alternative to chrome lining for things like AR barrels. Supposed to provide for very long barrel life without the accuracy problems sometimes associated with chrome lining.

Nitriding isn't hype. It's been around for over 50 years and was originally intended to harden bearing surfaces on crankshafts to prevent scoring under severe duty or long term service.

It works, and engine guys know it. Chroming cranks was tried - and getting a consistent thickness was discovered to be near impossible. Crank bearing surfaces must be held to a tight tolerance, with bearing clearances in the .002-.004 range typical. Chrome that is over .0005 in variance causes issues, especially in bores where it can spike pressures past the limit.

That's why chroming bores is an issue - you have to button oversize and chrome back to the dimension, where nitriding you finish to dimension then treat, which doesn't change it. That allows for a lot more control.

With crankshafts it also prevents flaking the surface off to become an abrasive. Nitriding works very well. And the European gun barrel makers all switched to hammer forged nitrided back in the 60's and 70s. So did many civilian pistol and hunting rifle makers here. It's the milspec chrome barrel makers who lag behind 40 years because our cost based taxpayer supported AR industry does things to military standard. It's a very conservative, old view of firearms.

Personally, I think Colt left it so they wouldn't have to finance a $3.5 million barrel hammer forge. It was to their profit. BUT - FN has one and is selling them now. Just like Ruger, Remington, and a lot of others do in their civilian guns.

Modern America is completely disconnected with actual factory production techniques.

Tirod said:

Nitriding isn't hype. It's been around for over 50 years and was originally intended to harden bearing surfaces on crankshafts to prevent scoring under severe duty or long term service.

It works, and engine guys know it. Chroming cranks was tried - and getting a consistent thickness was discovered to be near impossible. Crank bearing surfaces must be held to a tight tolerance, with bearing clearances in the .002-.004 range typical. Chrome that is over .0005 in variance causes issues, especially in bores where it can spike pressures past the limit.

That's why chroming bores is an issue - you have to button oversize and chrome back to the dimension, where nitriding you finish to dimension then treat, which doesn't change it. That allows for a lot more control.

With crankshafts it also prevents flaking the surface off to become an abrasive. Nitriding works very well. And the European gun barrel makers all switched to hammer forged nitrided back in the 60's and 70s. So did many civilian pistol and hunting rifle makers here. It's the milspec chrome barrel makers who lag behind 40 years because our cost based taxpayer supported AR industry does things to military standard. It's a very conservative, old view of firearms.

Personally, I think Colt left it so they wouldn't have to finance a $3.5 million barrel hammer forge. It was to their profit. BUT - FN has one and is selling them now. Just like Ruger, Remington, and a lot of others do in their civilian guns.

Modern America is completely disconnected with actual factory production techniques.

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If you can grind after chrome plating, you can hold very close dimensional tolerances. We do it all the time in the repair business and can plate to .002" thickness and still hold better than .0005" diametrical tolerances. Aircraft engines have had hard chrome plated shafts and bores since before WW2, not to mention just about every hydraulic piston since the turn of the last century, and they could keep very tight tolerances.

With barrels, you cannot go back over the plating to grind back to a desired dimension, so you are stuck with the variations in plating thickness. However, as far as barrel life goes, nothing beats chrome plating, except maybe a stellite liner, for extending life, especially if the barrel is going to be used in full auto extensively.

The major advantage of nitriding over chrome plating is the cost, due in large part to how much industrial waste you produce. Nitriding is much more environmentally friendly.

Salt bath nitriding QPQ is the surface hardening/finish used on guns..it leaves a black metal oxide on the surface

http://www.hefusa.net/melonite_qpq.html

Google qpq and you can read a lot more about it...

I associate nitriding with a hardening process and nitrates as a corrosive salt used to induce rusting AKA bluing/browning.

Edit: I believe many people confuse the two.

Nitrate = Low quality bacon.
Nitride = Surface hardening process.

Happens all the time.
Consider silicon (semiconducting element used in electronics) vs silicone (long chain compound used in actresses) vs silica (sand.)

And on topic for a gun, I read a long thread with a lot of discussion of bores and grooves and stuff and I don't think half of those people understood what was being measured.

"And on topic for a gun, I read a long thread with a lot of discussion of bores and grooves and stuff and I don't think half of those people understood what was being measured."

Heh, it seemed in the late 1800's, nobody knew what was being measured, either. I know, some measured bore diameter by land to land and others groove to groove. That is why a .303 British is larger in diameter than a .308, or why 7.62x51 is smaller in diameter to 7.62x54r even though both are 7.62.

It is a case of semantics with ide and ate, but in this case, the words have specific meanings referring to specific compounds that are related only in that they have nitrogen involved at some point.

But, there are guys out there that still think the F-14 and F-15 are more or less based on the same design.

Ash said:

And on topic for a gun, I read a long thread with a lot of discussion of bores and grooves and stuff and I don't think half of those people understood what was being measured.

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Heh, it seemed in the late 1800's, nobody knew what was being measured, either. I know, some measured bore diameter by land to land and others groove to groove. That is why a .303 British is larger in diameter than a .308, or why 7.62x51 is smaller in diameter to 7.62x54r even though both are 7.62.

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Yeah, they did, it is just that now people have forgotten what they old timers were measuring....

The two measurements used in caliber designation are not bore and groove diameters, but bore and projectile diameter.

.30 caliber, .303, 7.5mm, 7.62mm, 7.92mm are bore diameters. The .308 and 8mm are the projectile diameters. With a few exceptions, one of these two dimensions is used. Groove diameter are not usually used due to the fact that most rifling designs have differing groove depths. For example, the 5 groove Enfield rifling used in the M1917 with the .30-06 cartridge had .005" deep grooves, whereas the 4 groove rifling used in the M1903 for the same cartridge had only .004" deep grooves.

In the case of the 7.62x54R, the 7.62 is the bore diameter, the bullet diameter is .311"

In the case of the various .38s, which has a bullet diameter of .357/.358" and a bore diameter of .346" and a typical groove depth of .005" to .006". the .38 refers to the original bullet diameter of the .38 Colt which used a heeled bullet of .375" diameter for used in converted cap-and-ball revolvers that used the same diameter bullet.

Ash said:

But, there are guys out there that still think the F-14 and F-15 are more or less based on the same design.

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Ash said:

And on topic for a gun, I read a long thread with a lot of discussion of bores and grooves and stuff and I don't think half of those people understood what was being measured.

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Heh, it seemed in the late 1800's, nobody knew what was being measured, either. I know, some measured bore diameter by land to land and others groove to groove. That is why a .303 British is larger in diameter than a .308, or why 7.62x51 is smaller in diameter to 7.62x54r even though both are 7.62.

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Yeah, they did, it is just that now people have forgotten what they old timers were measuring....

The two measurements used in caliber designation are not bore and groove diameters, but bore and projectile diameter.

.30 caliber, .303, 7.5mm, 7.62mm, 7.92mm are bore diameters. The .308 and 8mm are the projectile diameters. With a few exceptions, one of these two dimensions is used. Groove diameter are not usually used due to the fact that most rifling designs have differing groove depths. For example, the 5 groove Enfield rifling used in the M1917 with the .30-06 cartridge had .005" deep grooves, whereas the 4 groove rifling used in the M1903 for the same cartridge had only .004" deep grooves.

Generally metric cartridge designations are "Bore Diameter" X "Case Length" (in millimeters) and US cartridge designations are "Bullet Diameter" (in inches or mm) and First Manufacturer", or parent case if it was derived from a wildcat. Take 7.62 x 51 (not to be confused with 7.62 NATO) and .308 Winchester, 7.62 is the bore and .308 in the bullet... In the case of the 7.62x54R, the 7.62 is the bore diameter, the bullet diameter is .311"

In the case of the various .38s, which has a bullet diameter of .357/.358" and a bore diameter of .346" and a typical groove depth of .005" to .006". the .38 refers to the original bullet diameter of the .38 Colt which used a heeled bullet of .375" diameter for used in converted cap-and-ball revolvers that used the same diameter bullet.

Ash said:

But, there are guys out there that still think the F-14 and F-15 are more or less based on the same design.

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heh, heh, close enough for most....

Some funny bore diameter ideas here, guys.

I know, some measured bore diameter by land to land and others groove to groove.

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No. Bore diameter is land to land, period. Because the tops of the lands are formed by the hole bored through the barrel blank to start with. Groove to groove is groove diameter, strangely enough. Except on the internet, apparently.

.30 caliber, .303, 7.5mm, 7.62mm, 7.92mm are bore diameters. The .308 and 8mm are the projectile diameters.

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OK, except for the 7.92 and 8mm. Also 7.9mm
7.9mm = 311", 7.92mm = .312", 8mm = .315" All to be found as bore diameters for the nominal 8mm cartridges. Early 8x57 had a .318" projectile, late has .323".

Groove diameter are not usually used

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In the American system it is common for the bullet to equal the groove diameter. At one time European practice was to leave room in the grooves for bullet metal displaced by the lands, so bullet < groove. I think they now tend to the full fit.

For example, the 5 groove Enfield rifling used in the M1917 with the .30-06 cartridge had .005" deep grooves, whereas the 4 groove rifling used in the M1903 for the same cartridge had only .004" deep grooves.

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Kind of an uncommon combination of standards. The 1917 with .005" grooves the same width as the lands actually has a "tighter" barrel than a 1903 with .004" grooves wider than the lands. Note that SAAMI specifies a barrel cross sectional area for each caliber so as to allow for different rifling forms.

Also, the 7.62x54R Mosin Nagant was introduced before the Russians went to the French system of measurement and was originally known as the "Three Line Rifle" where a line = 1/10 th inch. Bore diameter and with deep grooves for long service life. And mass production dimensions tended larger than spec; also seen in .303 British.

The bore diameter of many 7.62x54r rifles is .310 or .312, sometimes higher.

Ditto for .303 British.

Not ditto for .303 Savage nor .308 Winchester nor .30-06.

Jim Watson said:

OK, except for the 7.92 and 8mm. Also 7.9mm
7.9mm = 311", 7.92mm = .312", 8mm = .315" All to be found as bore diameters for the nominal 8mm cartridges. Early 8x57 had a .318" projectile, late has .323".

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But, to the Germans, officially it was always 7.92mm, which was always the bore diameter. the dropping of the "2" (7.92 vs 7.9) is just rounding, .38s were actually .375, and, per print US 5.56 mm barrels have a .219 bore or 5.5626 mm.

Jim Watson said:

In the American system it is common for the bullet to equal the groove diameter. At one time European practice was to leave room in the grooves for bullet metal displaced by the lands, so bullet < groove. I think they now tend to the full fit.

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Depends on the bullet material. solid lead bullets are oversized by quite a bit. Jacketed bullets can be slightly larger than the grooves. The M16 barrel has a groove diameter of .2235" to .2245", the bullet diameter is .2240" to .2245", the M14 had a bore of .3075" to .3095" and 7.62 M80 ball bullets are .3075" to .3085"

Jim Watson said:

Kind of an uncommon combination of standards. The 1917 with .005" grooves the same width as the lands actually has a "tighter" barrel than a 1903 with .004" grooves wider than the lands. Note that SAAMI specifies a barrel cross sectional area for each caliber so as to allow for different rifling forms.

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Okay, how about .303 British: Medford rifling with .0035" deep grooves and Enfield rifling with .0065" deep grooves, both had .303 bores.

Jim Watson said:

Also, the 7.62x54R Mosin Nagant was introduced before the Russians went to the French system of measurement and was originally known as the "Three Line Rifle" where a line = 1/10 th inch. Bore diameter and with deep grooves for long service life. And mass production dimensions tended larger than spec; also seen in .303 British.

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If you slug a number of Mosins you will find the bore is nominally .300"

And the ли́ния, or liniya was an Imperial Russian measurement...the French linge was 1/12 of a French inch and went out of use in 1799. Unless, by "the French system of measurement" you mean the metric system.

British picked .303 for the bore diameter so they could bore the blank with a .300 drill then ream .0015 off the radius to clean it up, not because they drifted off spec diameter. The British liked the use nominal sized barrel drills and ream oversized, whereas the reast of the worls bored undersize and reamed to nominal.

I've done Mosins for 20 years. I know the history, I know the measurements (I even use arshini in my novella Steel Ambition, and the follow on Steel Resolve). And Mosins are not nominally .300. They are generally .310.

Ash said:

I've done Mosins for 20 years. I know the history, I know the measurements (I even use arshini in my novella Steel Ambition, and the follow on Steel Resolve). And Mosins are not nominally .300. They are generally .310.

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That would make the grooves non-existant to .0015" deep.....


(.300" is the nominal BORE diameter.)

Looking in the 1911 ALFA catalog, for some reason they list the military models Mausers as 7.9 and the commercial rifles, even duplicates of military rifles as 8mm.

Lead bullets are a different game. We are usually told to use oversize cast bullets - I run .411"s in a nominal .408" .40-65. But there are paper patchers who load them at bore diameter over the patch.

You have to figure manufacturing tolerances in barrel and bullet diameters. Only the best match bullet and groove diameters agree very closely. Then there were the days of Palma matches when the host country provided the ammo. That led to tight .308s and standard .308s, depending on where the match was held.

The Metford rifling was not only shallow, it was well rounded and worked great with Mk I black powder .308. The deep square Enfield rifling was needed to stand up to Cordite, even Cordite MD.



I don't doubt the Mosin Nagant NOMINAL bore diameter is .300" (three lines). I wonder what they held in practice. Many many are larger than the spec of .310" in the grooves. Lots of oversize .303 British out there, too; I read one guy's adventures at .318", mighty near an 8mm J bore.

I do use "the French system of measurement" to mean the metric system. Too bad we didn't go with the Jefferson decimal system of weights and measures as we did decimal coinage.


Ash still hasn't realized the difference between bore and groove diameters.

How did we slip so far? Back when the American Rifleman was a technical publication instead of a political tract (necessary) and mild new product review collection, they made sure we knew such stuff.

Hey, Jim, don't patronize. I understand just fine, thank you. You're on the edge of flaming. I would expect more from you than that.

In any case the fact remains that when slugged, Mosin bores are always larger, typically .310-.312, than other nominally 30 caliber barrels such as commercial .308's. By bore, I mean groove to groove. If semantics are your problem, get over it. AS I MENTIONED EARLIER, grove to grove measurement. As part of this, 7.62x54r bullets are LARGER in diameter, typically .31 caliber, than 7.62x51 bullets, even though both represent metric measurements that are given to the hundredths place. The bullet designations thus do not accurately represent the bores into which they are to be fired nor do they accurately establish the diameter of the bullet.

I am not wrong on this. Period. Condescend all you want. What's really stupid about all this, about the pouncing, was the relatively whimsical observations that went behind my original statement.

In other words, a .357 has the same bullet size as .38, 7.62x54 uses a larger diameter bullet than 7.62x51 and into the same sorry putrid vein of this post a .308 is smaller than a .303. A .307 Winchester has the same diameter bullet as .308 Winchester and .300 Savage.

Ash said:

In any case the fact remains that when slugged, Mosin bores are always larger, typically .310-.312, than other nominally 30 caliber barrels such as commercial .308's. By bore, I mean groove to groove. If semantics are your problem, get over it. AS I MENTIONED EARLIER, grove to grove measurement.

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In a technical discussion, terminology is not semantics. It is right, or it is not.

This seems handy

Why do we hear so many detailed explanations of difference between "clip" and "magazine" but so much confusion with the difference between "bore diameter" and "groove diameter?" Also, as in the OP, "nitrate" vs "nitride" and "silicone" vs "silicon."

Sorry, Ash, the bore diameter is not measured from groove to groove in any barrel, any time and saying does not make it so.

Bore diameter has little bearing on loading for modern firearms, but it has been picked up and misused as a term for groove diameter which is readily measured off a slug or cast and does govern bullet selection.

Ash said:

In any case the fact remains that when slugged, Mosin bores are always larger, typically .310-.312, than other nominally 30 caliber barrels such as commercial .308's.

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Which goes back to the earlier post about metric vs US cartridge designations. the US usually goes by projectile diameter (nominally to groove-to-groove diameter), metric usually goes by bore diameter (land-to-land).

If the 7.62 x 54R was marketed in the US first, it would probably have gone by .311 Russian....

Ash said:

By bore, I mean groove to groove. If semantics are your problem, get over it.

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Well, you're wrong. Groove-to-groove is not the bore diameter....

Ash said:

AS I MENTIONED EARLIER, grove to grove measurement. As part of this, 7.62x54r bullets are LARGER in diameter, typically .31 caliber, than 7.62x51 bullets, even though both represent metric measurements that are given to the hundredths place. The bullet designations thus do not accurately represent the bores into which they are to be fired nor do they accurately establish the diameter of the bullet.

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The designation are accurate in what they describe, both 7.62 x 54R and 7.62 x 51 have a nominal 7.62mm bore.