S&W Melonite coated barrel vs Noveske chrome lined barrel.

[rsilvers]

HK pistol barrels are nitrided.

MR556 barrels are not nitrided.

[montrala]

HK pistol barrels are nitrided.

I have yet to find HK material that says so. Best I've digged from HK is that pistols have:

corrosion resistant “Hostile Environment” blued finish

and

one piece machined, nitro-carburized steel slide

No word on barrel finish.

Please point me to your source of info. I now that HK must be doing something to their pistol barrels back at Oberndorf. And I suspect that they do same to rifle barrels as uniform production process.

[rsilvers]

MR556 barrels are imported as blanks and finished in GA. HK MR556 rifles are assembled in NH. No one nitrides blanks. The MR556 is not nitrided. My source of information is HK.

[montrala]

MR556 barrels are imported as blanks and finished in GA. HK MR556 rifles are assembled in NH. No one nitrides blanks. The MR556 is not nitrided. My source of information is HK.

I asked about your info that pistol barrels are nitrided.

Anyway, since you mentioned rifle barrels - is you source HK Gmbh who makes them or HK USA that receives whatever HK Gmbh sends them? There are several known instances of "miscommunication" between HK Gmbh and HK USA, so I would not bet my hand on HK USA informations. I know that HK USA says that MR556 barrel is not nitrided or coated in USA, but they do not say what is done to this non-barrel things that came from Germany back in Germany.

[MarkG]

ACR, RGP, and AAC 300 AAC Blackout barrels are all nitrided because Remingon did extensive testing and the barrels did last 60% longer than chrome lined.

Has your extensive testing been independently verified? 60% longer than chrome lined under what conditions? Whose chrome, whose nitride? To many unanswered questions. Unless Remington is going to release its test results, your statement is markedly fuliginous.

The problem with nitriding is that it is an all or nothing process. As one example, what if I don't want the breach and muzzle threads hardened to C scale 70?

I know what I don't know...

[rsilvers]

My source is HK USA, but if you think HKO would nitride blanks before machining - well, that would be pretty odd, as the nitriding would be turned off the outside of the barrel and threads.

[rsilvers]

Has your extensive testing been independently verified?

No, but you are free to do your own test if you don't believe it.

Swiss Arms seems to rate their barrels at 20,000 to 30,000 rounds:

http://www.biggerhammer.net/sigamt/5...echinspection/

1. Barrel life: Test procedure

1.1 Firing sequence

The 15,000 rounds of the endurance trial shall be fired in strings of 100 shots in the following sequence:

20 rounds single-shot
20 rounds 3-shot burst
20 rounds fully automatic with measurement of cyclic rate
20 rounds 3-shot burst
20 rounds fully automatic

All 100 rounds within 60 seconds. Firing shall alternate between the normal hip and shoulder positions, with subsequent cooling of the hot weapon in water.


Stripping and cleaning

After firing 1000 or 7500 rounds respectively:

- fully strip the weapon and clean it thoroughly.

1.2. Inspection measurements

- Weapon as new:

- Accuracy

Fire a 24-round group, single-shot off the machine in a tunnel with a cold weapon at a range of 300 m. The 50 % windage and elevation dispersion shall not exceed a max. of 14 x 14 cm.

- Accuracy with Swiss ammunition Gw Pat.90

Checking at random rifles out of production, firing a 24round group with the Swiss ammunition Gw Pat.90 at a range of 300 m, of f the machine, the 50 % windage and elevation dispersion will be in the average only 7 x 7 cm. Any result from an individual weapon, will not exceed a max. dispersion of 11 x 11 cm.

- As new, after 1000 and 7500 shots:

Caliber : with SIG type caliber gauge
Clearance : with SIG type inside micrometer
Muzzle velocity : average of 10 rounds
Accuracy : average of 3 groups of 10 rounds fired single-shot off the machine in a tunnel at 100 m range

- After firing 7500 rounds

- Keyholing

In the hot condition, not more than 5 of the last 20 shots (of 71500 rounds) may create elongated holes. Firing shall be fully automatic at a cardboard target at a range of 5 m.

- Inspection

Heavy duty components such as the trigger action, bolt, receiver and gas piston are to be inspected for signs of wear. Barrels shall be measured and evaluated with bore gauges and inside micrometers.

-Greasing and assembly

Following each inspection, the weapon shall be suitably greased to allow further usage.

-Records covering the following shall be maintained.

Barrel inspection
Component inspections
Cyclic rate measurements
Projectile velocity measurements
Accuracy test firing
Malfunctions and defects

- Comments

The standard limits shall apply for any weapon being considered for rejection, i.e. max. 10% loss in velocity, or projectile instability resulting in elongated holes in the target bigger than 11 mm for more than 20% of the last 20 shots fired in the hot condition.

In any group of 24 rounds fired off the machine in the single-shot mode with a cold weapon at 300 m range:

- no more than 5 elongated holes bigger than 11 mm may appear in the target,
- the 50% windage and elevation dispersion may not exceed 28 x 28 cm.

[Dirtyboy333]

rsilvers: i read that Swiss Arms document before and its very impressive. Obviously the Swiss find nitriding superior.

If the only complaint is that nitriding is an all or nothing process that hardens the whole barrel..... well, then thats a pretty small gripe only affecting those wanting to cut or re-profile.

I for one like having the exterior of my barrel very hard and extremely corrosion resistant.

[jbsmwd]

So far, 75 gr Hornady TAP has been the most accurate grouping 9 shots at 1.15", but the 10 th shot opened it up some.

Info please!!!!! where did you buy it, how much, barrel profile.
The only ones I can find are the DS Arms barrels, umm NO, or the S&W barrel.

[MarkG]

No, but you are free to do your own test if you don't believe it.

A simple no would have sufficed. What I believe or don't believe is irrelevant. The burden is on you to back up your extraordinary claim.

Swiss Arms seems to rate their barrels at 20,000 to 30,000 rounds

Let's see here 60% / N X (A+B) = ......

So a chrome lined barrel is only good for 8000-12000 rounds?