I find German Engineering fascinating, not always particularly good, but fascinating.
Unlike the 9mm P7 which used a gas operated retarded blowback, the P7 K3 uses an oil filled buffer to aid in it's straight blowback system. The buffers which look like a small shock absorbers blew out quite frequently making the pistols inoperable except for 22 lr. Because of this the gun realized limited sales. H&K in turn quit making the replacement buffers rendering the guns useless.
An Engineer from Las Vegas went to Germany and consulted with HK and came up with a better design that lasts practically indefinitely. He is making and marketing the buffers in this country.
I find this a very strange setup.