Reply To: Help! Need more power from my Gamo Urban
Hi Chris, I just learned how to adjust the hammer spring pre-load by turning a screw inside a slide-off plastic end cap behind the hammer spring. You access the screw by removing the gun from the stock (take out both screws labeled #32 on the diagram below). On the diagram, part number 17 is called the “cylinder end cap”. The Urban has a slightly different shaped piece, but that’s the one to remove – it just slides straight back. The cylinder that this end cap fits into on the diagram holds the allen head screw that you turn to adjust pre-tension on the hammer spring. CW for more tension (ie, more power) and CCW for less tension – but don’t start by turning it CW, start by turning it CCW all the way so you have a refence point. That screw has 15 turns of adjustment but comes from the factory somewhere near the higher power end. The allen wrench you need is 4mm.
So insert the allen wrench and turn that screw all the way CCW until it doesn’t turn anymore – that is fully retracted and the lowest power possible (at least by this adjustment). Now turn that screw 15 turns CW and you’ll be at the max power setting. If you go to higher power first, there is nothing to stop the screw from going off its threads and you don’t know where you are starting from.
At max power, my Urban gives me 28 fpe when firing H&N Predator Polymag Shorts (15.89gr) – so I guess it would give me about 30 fpe if I used something heavier like 18.19gr JSBs. Beyond this simple adjustment, I’d refer you to one of the many more experienced Urban AG owners on this forum and on gta. They are very willing to share advice and suggestions. Good luck!
(oops – just saw someone posted this same advice – maybe this diagram is helpful to you)