Re: Grease nipple not a zerk
Your grease gun should be fited with a flexible hose or a solid "pipe" with fitting on the end to attach to a zerk.. Remove that and buy a 6" long piece of galvanized pipe threaded on one end. Obviously, the thread should be the same as your hose fitting. I think its about a 1/4" pipe, but I didn't go out to the garege to check.
Anyway, file down and smoothen out the non-threaded end with a small round file, so that it fits right over your fitting. Then when you use it just push down hard to keep the grease from squeezing out.
The original OMC gun had a nylon fitting on the end, and with only a small hole. My old filed piece of pipe has been greasing my Rudes for 40 years without a problem. Leaves a little more grease on the outside, but you can wipe it off in a second.