View Full Version : HKmp5k Buffer

February 15, 1999, 07:11 PM
my mp5k buffer turned "BUTTER" and im asking
this question in the full auto forum and 4v50GARY suggest i post it here.
im planning to buy a new buttcap and i want to make sure i wont happen again.
Pls. help me.


4V50 Gary
February 16, 1999, 01:06 AM
As a matter of clarification, Rey and his 15 year old MP5K are in the Philippines. The buffer is turning soft and I'm not sure whether its a reaction to the unnamed solvents, lubricants. Through a relative, he's getting a replacement part here in the US. He described it as pliable as butter and I take it that the polymer has reached the equivalent of its phase transition point. Any suggestions or polymer engineers out there?

Walt Welch
February 17, 1999, 12:40 PM
'Phase transition point?' And you are asking ME??

Well, jeez, I am no polymer chemist, but was a biochemist, and this sounds to me like the well known petroleum based product attacking rubber or neoprene problem.

Send him a Tuf-Cloth with his buffer. Probably won't happen again. Of course, 15 years is a long time to expect a rubber part to last. I change the hoses and belts in my cars every 5 years or so, just because I realize the neoprene will not last forever.

FWIW, Walt

February 17, 1999, 08:10 PM
im just wondering if this problem was been encountered by anyone also living in a tropical country & if this problem was addressed to Hk regarding the use of the neoprene material in their guns..should they change it something tougher?

note:all of our mp5k were fired only more or less 200 rds. ever since we bought them legally (15 yrs. ago)

4V50 Gary
February 17, 1999, 11:55 PM

Is that 200 rounds altogether or per year or month or what?

What type of cleaning solvents do you guys use and what type of lubricants? Walt Welch's suggestion of the Tuf-Coat (dry film lubricant) is good.


February 18, 1999, 02:56 AM
in 15 years a single mp5k has fired 200rds.
(read BUDGET)
sad to say our ever-changing armorers used
im planning to replace the buffer with a black rubber 1/4" thick and trim it. as temporary..

4V50 Gary
February 18, 1999, 04:17 PM
Heck of a tight budget and shooting 200 rounds over a 15 year period won't churn the buffer to butter. I suspect that Kerosene is the culprit. Ask your armorers to stay away from it and any non-gun care products.

Since WD40 leaves a film, it isn't ideal for firearms either. Remington was sued by a Texas man who shot himself when the safety failed. The safety failed because he used WD40 for over 20 years and the deposit grew so thick that it defeated the safety. When that rifle was placed in a vise, it took two large employees to separate the action from the stock (the owner never took the rifle apart to clean it). That's when Remington discovered the buildup of WD40. The jury felt sorry for the old man and held against Remington anyway (Sorry Rich, but after all, it's not their money). Good luck,


February 18, 1999, 07:11 PM
Thanks for the tip.
Kerosene & sometimes gasoline was used to clean (overhauling) guns here.
And WD-40 issue is new to us.
Thanks a lot again.
What about Break-free as lubricant?

Walt Welch
February 18, 1999, 07:54 PM
WD-40 sucks. Period. Gave my last can to my ex-wife.

The problem is that it is basically mineral oil with surfactants and a carrier. The mineral oil tends to gum up (incidentally, there was an article about the WD-40 company in the WSJ 6 or 7 years ago; they mistakenly said it was made of surfactants and mineral WATER, obviously a typo, but you still see people who should know better quoting that article).

The advantage of Sentry (Tuf-Cloth, -Glide, etc.) and Corrosion X products is that they have an extremely low surface tension, and will penetrate everywhere, while bonding to the metal; the thin film technology will even penetrate UNDER corrosion, and bond with the undamaged metal underneath.

Oil will simply coat the metal, including rust and corrosion, and not stop the rusting or corroding.

Try these new products out; you will be impressed. They are widely used in the knife industry. Walt

4V50 Gary
February 18, 1999, 08:04 PM
Mabuhay Rey!

Since I bought about a gallon's worth a while back, I use Break Free as both a cleaner and a lubricant. I'm partial towards Sentry's Tuf-Cloth which Walt mentioned.

Absolutely stay away from gasoline to clean your weapons, at least any part containing polymers.


[This message has been edited by 4V50 Gary (edited February 18, 1999).]