The finishing.com Hotline -- Serious Education ... plus the most fun you can have in metal finishing
Replacement ideas for Hard Chrome plating of gun barrel bores
Q. Dear Sir,
The hard chrome plating process has lot of hazardous environmental effects. It is in use for gun barrel bores for protection from wear. Please advice of its replacement, i.e., Electroless Nickel phosphorous composite coating or any other coating.
Please also clarify that electroless Nickel phosphorous coating has better adhesion/corrosion and abrasive wear resistance, and better hardness after heat treatment and lower friction than Hard Chrome plating.
- Multan, PAKISTAN
A. Hello Mian. Although hard chrome plating presents hazards that must be managed, and although electroless nickel is a great material and usually has better corrosion resistance, I don't think that any of the assertions you have asked for confirmation about are true.
Ted Mooney, P.E. RET
Pine Beach, New Jersey
A. Some firearm producers in the US are offering EN plated items. EN protects the gun both outside and inside the barrel. As Ted said, EN should not be taken as a chrome replacement but an alternative that has to be carefully evaluated in each case.Guillermo Marrufo
Monterrey, NL, Mexico
The hard chrome plating of gun bores was classified info a few years back. It may still be.
I do not think that it was ever classified in the military sense, but it certainly was extremely proprietary. There are several firms that do it now, but is beastly difficult to do, as you do not want to strip a weapon.
Chromium plating of gun bores has been widely practiced since at least WWII. With no security clearance, I have been in U.S. facilities that do it. There is at least one highly detailed technical article in the metal finishing journals with the title "Chromium Plating of Gun Barrels", which goes back to 1957; and no one is working towards removing that article, because it's still in today's widely published data bases. So I know that the mere fact that gun barrels can be beneficially chromium plated is by no means a secret. That is not to say, of course, that there are no classified facts related to the possible chromium plating of some gun barrels -- there certainly could be.
If one would rather not discuss the topic in public, or in a letter addressed to a mideast reader, that is okay; however, the tone of the letter seemed to imply that the inquirer already knew how to do it and was now looking to address the environmental implications of chrome plating. But thanks for the reminder that the whole world can read this forum and no information should be posted that we are not willing to share with the whole world, Todd.
I had small caliber long bore weapons in mind, not naval guns or artillery. The classified information part is strictly hearsay though, as it is hard to get a hold of classified information. I have no objection to sharing information with people of Pakistan or its manufacturing of weapons. In fact I am going to go renew my NRA membership now.
I was in a hard chrome shop in Connecticut years ago. They were hard chrome plating the bores of M-16 rifles for Colt. Their process was entirely straightforward, conventional chemistry, amperages, etc, and the fixtures were rather simple. There was no attempt to maintain any parts of the process as secret or proprietary, and any decent hard chrome shop could duplicate what they were doing. I also own two Winchester M101 shotguns, made in Japan, one in the early 60s, and one in the late 70s. Both have hard chromed bores, and they were manufactured in the 10s of thousands.
A. Comprehensive answer to the question with information freely available on the internet (which does surprise me).
Special Processes - Yeovil, Somerset, England
February 14, 2012
Thanks, Mark -- a wonderful paper, and I'm shocked that this information is freely available on the web. We must be loony to reveal so much precise detail about exactly how the U.S. military's weapons are manufactured.
Personally, I don't understand the paranoia over chrome plating. Yes, we should be very careful about practices that expose workers to carcinogenic fumes or liquids, or which release hexavalent chrome to the environment, but that's not the same thing at all. Every process is hazardous if you don't contain it, but most, including chrome plating, can be innocuous if you do. And chrome plated surfaces are safe; you can eat off of them (I even have a copper-nickel-chrome plated fork from the '50s).
Countless dollars spent in the military and automotive industry on countless different replacement approaches, none of which will be universal because no other process is as good -- but no serious money spent towards eliminating the dangers of chrome plating instead of eliminating chrome plating itself :-(
Ted Mooney, P.E. RET
Pine Beach, New Jersey
July 18, 2012
"Countless dollars spent in the military and automotive industry on countless different replacement approaches, none of which will be universal because no other process is as good -- but no serious money spent towards eliminating the dangers of chrome plating instead of eliminating chrome plating itself :-( "
although I have already read thousands of your posts in the forum, I have never posted anything. These lines from you are really classic.Thanks.