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Phosphate coating on M4 barrel?


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Greetings all,


Although I've frequented---and enjoyed---the forums in the past few months,

this is my first post... It's a pleasure to be joining the community!


After a lot of research and a long wait, I will finally

be picking up my new Benelli M4 this week and can's wait!


I am trying to understand what type of coating is on the barrel of the M4

because I want to know how to care for it properly. I've searched quite

a bit, but the only information I have been able to find is that the barrel is

coated with "heavy phosphate" (see pg 14 of the M1014 operator manual,

available by googling "farrarsodfarm" and "USMC_M1014.pdf"....(I can't post links yet))

but not what specific kind of phosphate coating is used. There are many

different types of phosphate coating, each of which requires different care.

Google, for example, "heavy phosphate" and read about the different types

at "engineersedge")


In particular, phosphate coatings are quite porous, and will (generally speaking)

easily wick moisture in the air and rust accordingly. The phosphate is designed

not as an end-all protective coating against corrosion, but rather a medium in which

the *real* anti-corrosion coating can be easily suspended. For parkerized finishes

(which encompass many types of phosphate coatings), it is cosmoline or grease,

suitably wicked by the porous phosphate finish, that prevents against corrosion.

Google, for example, "xavierthoughts" and "parkerizing".


So does anybody know exactly what type of phosphate coating is used on the Benelli m4

barrel? (e.g. Type M, Class 2 or Type Z, Class 1, or....)


What are you M4 owners doing to care for your barrels, especially those of you who

use them in moist environs? The M1014 manual linked above recommends light oil like

CLP or MILITEC (see pg. 60). Is anyone slathering their barrel in cosmoline or axel grease and baking at 350 F?


Thanks all for the great posts and for the help.

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Man, I don't know what type of phosphate coating is on there, but I tend to fall back on my Marine Corps experience and use CLP on just about everything. That's what I've got on my M4, and I'm not concerned with it. I'm sure there are better things out there than CLP; but it's cheap and plentiful, and I've never had trouble with it.

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Far less trouble than a 590 that's for sure. I'm not a good example though. My side of Az has very little humidity. However, I've drenched it in sweat and never bothered to re-oil afterwards. There is no finish burning or prints. I don't have corrosive sweat like some guys do. Mine has been rained on quite a few times too.


Oiled rags never show the signs of surface rust, ie: red hued patches with oil or solvent when I bother to clean it.


The rest of the shotgun is type 3 anodized and stainless steel.


The res

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Thank you both for the comments and suggestions. I picked my m4 and went shooting yesterday, and I couldn't be happier with it! So far, I'm just sticking to CLP on the phosphate

coatings, as it sounds like this will be more than sufficient. Thanks again!

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