My custom built Grendel

[glane5910]

I blast most parts with aluminum oxide 80-100 grit at around 80 PSI. I don't see the need to blast new AR uppers/lowers etc. They have a good base hard anodizing. I just degrease them really well, spray and bake. Same goes for AR bbls. I like shooting Cerakote over the parkerizing. It makes for an even tougher finish IMHO.

[LRRPF52]

Dr. Killjoy on the Brownell's videos said that blast prep was necessary for Cerakote, so I decided to test it out with just a detailed washing and degreasing on some of my parts. I totally agree that a hardcoat anodized aluminum receiver or part, as well as a good parkerized part does NOT need to be blasted.

I even coated my stainless AA Grendel barrel without blasting it, and the FDE Cerakote ended up with a nice, deeply matte textured finish like it does on everything else.

I then wanted to see how it would adhere to nitro-carburized barrels, so I did one of them with no blasting, just a good degrease with acetone. Same results. Nitro-carburized surfaces are usually 70 Rockwell hardness, which is much harder than your hard chrome and other surfaces. I have taken metal files to these nitro-carb'd barrels, actually trying to file the surface, and the file just slips off.

LRRPF52

[Mav714]

Awesome rifle! Hope it shoots as good as it looks!

[z06man]

Dr. Killjoy on the Brownell's videos said that blast prep was necessary for Cerakote, so I decided to test it out with just a detailed washing and degreasing on some of my parts. I totally agree that a hardcoat anodized aluminum receiver or part, as well as a good parkerized part does NOT need to be blasted.

I even coated my stainless AA Grendel barrel without blasting it, and the FDE Cerakote ended up with a nice, deeply matte textured finish like it does on everything else.

I then wanted to see how it would adhere to nitro-carburized barrels, so I did one of them with no blasting, just a good degrease with acetone. Same results. Nitro-carburized surfaces are usually 70 Rockwell hardness, which is much harder than your hard chrome and other surfaces. I have taken metal files to these nitro-carb'd barrels, actually trying to file the surface, and the file just slips off.

LRRPF52

LRRPF52,

Where do you get your barrels nitro-carburized and how much does it cost? Can you do it post manufacture, i.e. is it thin enough not to interfere with the bore diameter?

[LRRPF52]

Sorry for the late reply. I have purchased all my nitro-carb'd barrels from AR Performance. Yes, you can have it done to barrels after they are chambered & finished. You just have to make sure they are bone dry clean. Nitrocarburizing doesn't add surface thickness, and it is not a coating or plating like chrome, TiN, etc. It is a quench-polish-quench process that introduces nitrogen into a high-temp kiln to change the crystalline structure of the steel so it is more dense on the surface. It is also known as Melonite, which Glock and other makers do to slides.

It's catching on pretty quickly with rifle barrels now, and I have bench rest friends that are doing it to match-grade barrels, with amazing results as far as accuracy life and really no fouling. There isn't any place for fouling to stick to, like on normal barrel surfaces with larger crevices in the steel structure. If you have a great barrel that shoots really well, you can clean the crap out of it, get it nitro-carburized for about $60, and extend the accuracy life up to 100%.

Eventually, the throat will get burned if it's a burner caliber, but that process is extended significantly, so for guys with 6mm's, 6.5x284's, 7mm WSM's, or 300x.338 LM's, it makes a lot of sense to get it done.

One thing I have noticed is that when I drop a sized piece of brass into a nitro-carb'd pipe, it rings like a tuning fork for a long time, and chambering and extraction are extremely smooth. Harrison at AR Performance claims that these barrels eat Wolf like it's going out of style, since the porous steel cases have nowhere to stick to during extraction.

I'm actually going out this weekend to test how some of the 5.56 nitro-carb'd pipes do with some 69gr SMK hand loads, as well as Wolf for reliability. I really wish Harrison could be licensed to make Grendel barrels and his improved bolts as a combo, because that would take the Grendel to a different level really.

[glane5910]

Thanks for the added info. Post how they work out.