Sounds more like human err than equipment failure. Usually when a zerk
fitting will not take grease it's because the grease in the fitting or just
beyond it has hardened and it takes more pressure to break it loose than the
pressure being exerted to hold the gun against the fitting or the gun is not
aligned correctly to the zerk.
On straight, not angled fittings, there is a tool made that clears out
hardened grease in a zerk. It's merely a tube with a rod inside to act as a
piston and the nose fits a zerk. You put some light oil into the cylinder,
put it on the zerk and then hit the top of the rod with a hammer. This will
open the zerk and passage ways.
Dick

--
Richard H. Neighbors
Building and repairing fine billiard cues for real pool players at
affordable prices.
Over 35 years exp. Located in Cincinnati OH
ph.# 513 233-7499
e-mail
web site http://www.dickiecues.com
"Jordan" wrote in message
...
Ivan Vegvary wrote:
I'm tired of not being able to force grease into chassis fittings with my
existing grease guns.

Suggest just try a good quality nozzle - the bit that fits onto grease
nipple. They all seem to be the same thread (?), and might be a better fit
to the nipples.