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Crusher trigger

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xyon View Drop Down
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    Posted: 18 May 2017 at 12:44am
I recently got a crosman crusher second hand. It's the bog standard crosman/gamo 25 piston 100mm stroke engine, but with a gas spring. The trigger is not great on these, so I decided to mod it to give a true second stage the same as a GRT or GTX trigger would. I drilled a hole through the trigger tapped it and installed a grub screw that presses on the sear to give the first stage lift. I also filled to void inside the trigger body with epoxy resin to better support the grub screw in position.


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Post Options Post Options   Thanks (0) Thanks(0)   Quote nunga Quote  Post ReplyReply Direct Link To This Post Posted: 18 May 2017 at 1:49am
how did that work out for you? shouldnt think it would improve the pull weight at all but at least you should know when it is going to fire
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Post Options Post Options   Thanks (0) Thanks(0)   Quote xyon Quote  Post ReplyReply Direct Link To This Post Posted: 18 May 2017 at 8:24am
Hi Nunga,
I wouldn't say it's an awesome trigger, but is much better.
As I'm sure you know, the pull of the faux first stage in the original is just a (rather stiff) spring, which I removed. The distance from the grub screw to the trigger pivot is about 1/2 the distance of the original lift point. So that would reduce the force by 50% but it's not that simple. The secondary sear's pivot location is working against us so the reduction in force is not quite 50%
Most of the trigger weight is the friction from the sear and trigger being forced together by the main spring. So that is where a polish of the sears helps + a bit of molly.
The weight of the second stage pull would be almost the same as the original minus the spring I removed. I adjusted the grub screw so the second stage travel is very short, so yeah, Tongue the main advantage is the predictable break point.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Pauly5 Quote  Post ReplyReply Direct Link To This Post Posted: 18 May 2017 at 9:22am
Nice work. Predictability is paramount. I have a Daisy 953 that has a stiff trigger, but with a polish is is smooth and reasonably predictable, which is an improvement.
I see you have a Zoraki too. Have you played with that trigger?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote xyon Quote  Post ReplyReply Direct Link To This Post Posted: 07 Aug 2017 at 10:55pm
To mod the trigger, install the grub screw in the position shown. The trigger will most likely be hollow in this area so fill with JB weld or epoxy. (clean all traces of oil/grease first) Drill and tap after it's cured. Use the vibratite (or PVA glue works!) to stop the screw from moving after you have adjusted it, but will allow future adjustment.

Remove the spring in the trigger, it is not needed. (keep the other spring(s) that act on the sears.)
Round off and polish the tip of the screw for smooth operation.
The closer the grub screw is to the pivot (without touching it) the more distinct the first and second stages will be.

There will probably be a small amount of play in in the trigger, which you can ignore, but if it bothers you there are 2 solutions. Install a second grub screw in the front part of the trigger, but this could affect the safety, so I preferred to add a small bushing around the pin (on the right of the pic). about 7mm diameter. The trick is to find the size which just takes up the play, any bigger and you will start to reduce the sear overlap.

Thanks to Steve in NC who's picture I have hacked.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Gabion Quote  Post ReplyReply Direct Link To This Post Posted: 07 Aug 2017 at 11:03pm
thanks for sharing - very helpful!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Gabion Quote  Post ReplyReply Direct Link To This Post Posted: 10 Aug 2017 at 10:43am
Hi xyon, can you please tell me where you got your grub screw from and what size you ended up using? Called on at a couple of places today and smallest they had were 3mmx5mm which am thinking will be a bit short. I assume you used a hex socket head?
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Post Options Post Options   Thanks (1) Thanks(1)   Quote xyon Quote  Post ReplyReply Direct Link To This Post Posted: 10 Aug 2017 at 3:09pm
I got the grubs screws from blacks fasteners M3 diameter 20mm long I think. (use a 2.5mm drill bit)
Yep they have a hex socket in the end, so you can screw the screw right up inside the trigger.

http://www.blacksfasteners.co.nz/Contact-Us/Blacks-Fasteners-Christchurch-Stores-Sydenham-Store-__I.10982


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