The reason is - despite the claims Gamo makes in all their ad's - it's not a true 2-stage trigger. This writeup explains why. Jim wrote it specifically for the Chinese copy of the Gamo - but it applies with equal accuracy to all.
If you want info about a true 2-stage trigger for your 440, click on the "GTX" button at the top of the forum page.
B18 trigger - by Jim P.
Trigger Adjustment
The B18 has a "two stage adjustable trigger." Well sort of. But it is not a "real" two stage trigger so be careful in your adjustment of the one screw! (I have a hole in the ceiling of my garage from learning this lesson and it could have been much worse - so read carefully before you start "adjusting" your adjustable trigger.)
First how does a trigger work. All mechanical triggers work by sliding two pieces of metal until one can slip past the other. The simplest example I can think of would be to put a pin in front of your piston. Then as you slowly withdraw the pin (two pieces of metal slide on one another) until it is finally out of the way and the piston slides forward. In order to make it easier and a little more precise there are usually one or two extra levers involved in a trigger. But the principal is still the same, two pieces of metal somewhere slide on each other until the piston is released.
A two stage trigger has two distinct stages - the trigger moves easily for a while and then there is a definite change to a slightly harder pull and the gun goes off.
A "real" two stage trigger moves the sliding pieces of metal with that first easy stage. It is an additional safety feature. There is a lot of overlap on the sliding metal pieces so if the rifle is bumped or dropped there is still a lot of metal to metal contact to prevent the piston from going forward without the trigger being pulled. All most all of this overlap is taken out with the first stage. Once the first stage is "taken up" (i.e. you get to the increase in pressure) the mechanism is balanced on a "knife edge" and just a little more pressure will shoot the gun. This is safe and effective trigger (but it is not a Qb-88 trigger!)
The B18 trigger is NOT! a "real" two stage trigger - it feels like one but it isn't! When you "take up" the first stage of the B18 trigger all you have done is move the trigger against a spring - nothing else. It then contacts the lever that will move the sliding metal pieces this is the "second" stage you feel. You then begin to slide these pieces and when one gets out of the others way the gun goes off. You want some travel in this second stage! If you set it on a "knife edge" (as I did) It will feel like a very good "two stage" trigger - but in fact it is unsafe! The slightest bump - even though your finger is no where near the trigger - will cause the gun to go off. And even if that doesn't happen after enough wear the edge will round off and the gun will go off after it is cocked (thus the hole in my ceiling.) I would make sure that I had at least 1/4" of trigger travel in the "second" stage.
So what you are adjusting by turning the single screw is the overlap of the two metal pieces that release your trigger. Turning the screw in (right hand screw) reduces this overlap and shortens the length of your "second" stage. Backing the screw out increases the overlap (and safety) and lengthens your second stage. This is the only adjustment on this "adjustable" trigger. I would say again at least 1/4" of trigger travel in the second stage is required as a minimum. If you adjust it to be like a match trigger - It is dangerous!
The trigger should be smooth. If it isn't - remember the "Two thousand pellet tune." it will work in. Or you might disassemble it (using Theoben's diagram and instructions) and polish and lubricate it to make it smooth. Again be careful and don't round off the sharp edge that keeps the trigger from releasing. The easiest thing to do is add a little oil and just shoot it - it will smooth out.
I don't think that anyone can make this a great trigger without making it dangerous. Just my opinion. You can learn to shoot well with this trigger however.
JK's Airgun Forums, moderators, and administrators are not responsible for any problems that may occur from reading or using content posted on this forum, as they are the exclusive responsibility of two parties: the person who posted it and the person who acted on said posted information.Use of our forums by people under 18 years old is allowed only with legal guardian(s) present.
