Ben, from a dull memory my hand pumped grease gun supposedly can create up to 2000lbs pressure which should be more than enough to encourage grease to flow..?
In order to generate pressure in the area to be greased, the grease gun requires to lock on to the nipple, thus nipple type plays a part as does the nozzle on the gun.
If the length of thread on the nipples is too long they may be up tight against the king pin or other obstruction thus blocking off the hole..?
I tend to apply grease every 300 miles or so. Replaced my kingpins and bushes at circa 33k miles.
