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Hw100 low power


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Thought my Hw100 was shooting low power the last time I used it so a lad came to chrono it with his fx chronograph and to my dismay it's only shooting 8.4 ft/lbs using jsb exact 7.87 grm. It's never ever lost any air so any ideas what's causing this the rifle is only 2 years old and was bought new. Disappointed is a understatement 😞

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If it's holding air ok but just low power there are two or three possibilities. A) It's been slowly loosing power over time and you've not really noticed the gradual decline due to the hammer spring taking a bit of a set. B) The regulator pressure has dropped. C) You are losing a quantity of air out of the breech when you fire.

The hammer spring can be adjusted - not too much of a problem but you will need to remove the anti-tamper, again not much of a problem.
The regulator can be adjusted - better with a reg pressure gauge but not necessary. Not too much trouble.
Breech O ring needs replacing. 

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It will be the grease they put on the hammer spring slowing it down. take the stock off, undo the two cap screws holding the trigger block on then remove the block, it's a unit don't fret, the hammer spring is above the trigger block, you can't miss it.

What you do then is use an artists brush and a tin of WD40 to clean the grease off, simple as that then it should be fine.

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