Help! Need more power from my Gamo Urban

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Hi Slash91,

By far the biggest gains in power would be from the transfer port size, valve volume, hammer spring tension and barrel length...probably other things too, but these are the main culprits in when looking for ways to increase power. I also recommend a regulator as it will produce consistency (regulator chamber volume, or plenum space also matters if you add this option). In your case the transfer port and the barrel port must match up to to at least 4.5-5.0mm in diameter, preferably closer to 5.0 mm for the biggest gains in power. Remember the pellet has to slide over the barrel port, so it can't be too big or the pellet will get damaged. The valve should not be restricted in any way, some bsa valves (not sure if yours does or not) have an insert that takes up valve chamber volume. This should be removed or volume chamber increased by machining more space into the valve. You can choose a heavier hammer if needed, but the stock hammers are usually enough to produce high power (30ftlbs+) in a .22 caliber with a little tweaking of the tension screw. Just doing these mods should put your JSB 18 grainers @ 900fps or more.

By doing these mods and adding a regulator you can make the gun shoot anywhere from 12ft/lb (or lower) all the way upto full power. Changing springs thickness, regulator pressure, and volume spaces gives a lot of control!

Nick
precisionpneumaticproducts.com
 
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I thought about starting my on thread but it seems like my question fits in here. Going to opposite direction, will lower power give any significant gains on shot count? I bought my urban used ski don’t know of the original owner changed anything but I get about 30 shots before the POI starts to change. I mostly target shoot and haven’t shot at anything larger than an English sparrow but want enough power to safelykill a raccoon if needed. No chronograph so I don’t know what speed I’m shooting right now.
 
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Hi Chris, I have an Urban and have done a lot of experimenting ...Have you tried to adjust the hammer spring tension? Also I would recommend installing a regulator, then you can adjust accordingly...There are limits to what you can do without adjusting plenum volume, changing hammer spring and resizing the transfer port... I have mine with a Alteros Regulator, but would probably do a Huma Next time around, if you set the regulator pressure higher and adjust the hammer spring all the way in, you can increase power but as I said with limits...I prefer my gun shooting around 820 fps with 14.35 JSB, more accurate and good out to 50 yards... Hope this helps
Click to expand...

No mods needed for that other than turning the hammer spring down. 
 
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