MK262 and maintenance

[17K]

If a person runs mostly MK262 rather than M855 or 193 is there increased wear or decreased parts life associated with the hotter ammo?

The majority of my shooting is MK262 through a Colt LE6920.

[ColtSeavers]

How many rounds of it do you shoot through any particular gun in a Day/Week/Month/Year?

Is your gas/recoil system tuned to this load in any gun you shoot it with?

Do you regularly inspect and maintain your guns?



I doubt you'll ever notice a marked difference, but you can always use quality parts, and fine tune your gas/recoil system for your particular load and have nothing but a benefit regardless.


Here's a good read:
http://www.shootingtimes.com/ammo/special-forces-to-civilians-black-hills-mk-262-mod-1-review/

[El Pistolero]

They are all 5.56 pressure ammo so I'm not sure there would be much difference.

[RAM Engineer]

I’ve never heard that 262 was any hotter than normal stuff.

[Inkslinger]

The muzzle velocity of Mk262 is less than M193 so wouldn’t that result in a slightly longer barrel life?

[ST911]

If a person runs mostly MK262 rather than M855 or 193 is there increased wear or decreased parts life associated with the hotter ammo?

The majority of my shooting is MK262 through a Colt LE6920.

In a word, no.

How much of it are you shooting, and are you shooting genuine Mk262 or an imitation?

[Spin Drift]

My understanding regarding Mk 262 ammo was besides the grain weight... you can scroll down to the Mk 262 part and read the rest. Shoots bug holes for me. I've had good luck with FGMM 69s as well.



https://en.wikipedia.org/wiki/5.56×45mm_NATO#Mk_262

[17K]

I mostly shoot IMI and CBC 7gr SMK loads. The guns I use are functionally stock 6920s with H2 buffers.

[ST911]

I mostly shoot IMI and CBC 7gr SMK loads. The guns I use are functionally stock 6920s with H2 buffers.

Not Mk262 then.

Short answer still no, but you'll have to check with those manufacturers and any testing to determine what pressures they might be running and resulting effects.

[mgrs]

If a person runs mostly MK262 rather than M855 or 193 is there increased wear or decreased parts life associated with the hotter ammo?

The majority of my shooting is MK262 through a Colt LE6920.

Yes, but as mentioned above probably not enough to matter. Lubrication, firing schedule, gas system tuning, and suppression probably affect it just as much if not more.

Looking at my guns with a bore scope, the douglas 18" spr barrel ( EDIT: 1100 rounds, almost all suppressed, all 77gr heavy reloads) even under slow fire is taking more of a beating to the gas port than expected:
https://i.imgur.com/oQYYvmP.jpg

This is a LaRue 16" lightweight barrel with 1400 rounds (much faster fire, 99% .223 pressure reloads) is doing better even though the port is 2" closer:
https://i.imgur.com/PQ1HxzM.jpg

Maybe not the most instructive comparison, as I do not know what LaRue's barrel steel is.

[5.56 Bonded SP]

The muzzle velocity of Mk262 is less than M193 so wouldn’t that result in a slightly longer barrel life?

In my opinion

Velocity is a factor, but so is powder burn rate and characteristics among other things. A faster bullet with slower powder might erode throat at a lesser rate than a slower bullet with faster powder.
OP, if it is factory ammo I wouldn't worry about it. If it is handloads, just keep your loads in spec and don't worry about it.

[5.56 Bonded SP]

Yes, but as mentioned above probably not enough to matter. Lubrication, firing schedule, gas system tuning, and suppression probably affect it just as much if not more.

Looking at my guns with a bore scope, the douglas 18" spr barrel ( 110 rounds, almost all suppressed, all 77gr heavy reloads) even under slow fire is taking more of a beating to the gas port than expected:
https://i.imgur.com/oQYYvmP.jpg

This is a LaRue 16" lightweight barrel with 1400 rounds (much faster fire, 99% .223 pressure reloads) is doing better even though the port is 2" closer:
https://i.imgur.com/PQ1HxzM.jpg

Maybe not the most instructive comparison, as I do not know what LaRue's barrel steel is.

Thanks for sharing. Noob question but are those barrels made of the same material?

[SomeOtherGuy]

Thanks for sharing. Noob question but are those barrels made of the same material?

The Douglas barrel would likely be 416R (barrel-rated stainless steel) and LaRue calls their mystery alloy "Rearden Steel." As far as I know LaRue doesn't say exactly what alloy it is, but it's a fair guess that it's a stainless alloy that's a little stronger than 416R, such as 410, 17-4PH, or some custom alloy like those. In short, they are probably not the exact same material, but we don't know for sure. It would not be radically different because there are no radically different stainless steels that would be suitable for a barrel and not cost far more than what LaRue charges for the barrel (which isn't cheap, but isn't cobalt-superalloy expensive either). The borescope photos certainly suggest it has greater resistance to heat erosion.

[5.56 Bonded SP]

The Douglas barrel would likely be 416R (barrel-rated stainless steel) and LaRue calls their mystery alloy "Rearden Steel." As far as I know LaRue doesn't say exactly what alloy it is, but it's a fair guess that it's a stainless alloy that's a little stronger than 416R, such as 410, 17-4PH, or some custom alloy like those. In short, they are probably not the exact same material, but we don't know for sure. It would not be radically different because there are no radically different stainless steels that would be suitable for a barrel and not cost far more than what LaRue charges for the barrel (which isn't cheap, but isn't cobalt-superalloy expensive either). The borescope photos certainly suggest it has greater resistance to heat erosion.

Interesting. Thank you for the informative reply.

[mgrs]

Thanks for sharing. Noob question but are those barrels made of the same material?

I realize there is a typo in my post- the douglas as 1100 rounds, not 110. Will edit.

I doubt it. The douglas is confirmed to be 416 SS whereas LaRue does not share what steel is used. It is stamped "Rearden Steel" in a nod to Atlas Shrugged and is one of LaRue's in-house barrels. I would have thought they are a less expensive material like 416 as it is common for cheap, accurate barrels, but it is wearing more like a nitrided barrel. I think nitrided or not could be confirmed by testing surface hardness, but I am not equipped to do that. The throat also seems to be eroding slower. Combined with the very deep grooves and sharp lands in the LaRue, I bet it would have a very long useful service life.

Another interesting observation, the LaRue tube pictured has a visible bur where the port was drilled, but still shoots very well for the first couple groups until it heats up. I would not expect a predatar barrel to not open up as it gets hot.

Neither of these have been abused although the LaRue has been allowed to get much hotter. They're both longer barrels though, SBR barrels seem to suffer worse than most anything else.

EDIT: Someotherguy beat me to it on the steel guesses.