Author Topic: Airgun Trigger Overhaul  (Read 8833 times)

Offline Stefan Pynappels

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Airgun Trigger Overhaul
« on: July 07, 2009, 05:35:02 AM »
Hi Guys,

I'm looking for some help with a project I want to try. First some background....

I live in Northern Ireland, and the gun laws here are fairly draconian. To own an air rifle, I had to apply for a full Firearms Certificate which took about 8 months. I bought a Cometa 300N air rifle, which is a nice little rifle which works well and I really like it. However, it is slightly let down by its trigger assembly, which is a little rudimentary, so I would like to build a better trigger assembly from better materials. I've been told to sell it and get another rifle, but I like this one, it fits me well and I like a challenge, besides which I don't want to have to wait another 8-10 months to get another rifle added to my certificate. I am only interested in air rifles in any case, so I don't want more hassle with my certificate.

Anyway, this is what the parts look like disassembled, I want to attempt to make all these parts new.
(See pic attached)
The middle bit is actually made from thin sheets of steel which have been stamped out and rivetted together, I want to machine this from solid material so I can get a good polish on the contact faces. Is steel the best material to use, or should I consider other alternatives?

I think the trigger blade part will be the most difficult, so I'll leave that to last, but ideas would be welcome, as you can see in the photo, it has a bent piece which acts on the middle piece, but there is also a spring integrated, so this will need some thinking.

Any help wrt to materials to use etc would be gratefully received.

Stefan.

Offline rleete

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Re: Airgun Trigger Overhaul
« Reply #1 on: July 07, 2009, 07:16:22 AM »
Steel, without a doubt.  The sear (part where middle thing catches on left thing) will need to be hardened on both pieces.  You need to get the geometry of the sear correct, or it will affect the trigger pull and break point.
Creating scrap, one part at a time

Offline Stilldrillin

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Re: Airgun Trigger Overhaul
« Reply #2 on: July 07, 2009, 12:08:53 PM »
Have you tried polishing/ improving what you have already got.  :thumbup:

Most mechanical mechanisms can be improved, at least a little, & this will give you the feel of a better (or worse) assembly.....

I polished the action of my (then) Ruger revolver, straight out of the box..... And won the next bowling pin comp!  :ddb: :ddb:

David D
David.

Still drilling holes... Sometimes, in the right place!

Still modifying bits of metal... Occasionally, making an improvement!

Offline RipSlider

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Re: Airgun Trigger Overhaul
« Reply #3 on: July 07, 2009, 02:34:26 PM »
If the rifle is on an FAC1 then you will need to take it back to get re-examined if you alter the firing mechanism, or actually pretty much anything apart from adding a silencer or re-working the stock. Check with your local Fire Arms officer, but I know I can't do much at all on my (centre-bore) rifles without getting re-checked. Anything not on FAC ( shotguns and air rifles ) are OK though here in england.

<<That's right american gun fans - it may need  more paper work than you can shake a stick at to get a rifle in the UK, but silencers are totally legit - which is useful >>

If you want to upgrade the rifle from a practical point of view, you will almost certain get much more value and pleasure - and a lot more rabbits - out of taking the time to convert to a Theoben gas strut than you would re-working the trigger.

If the trigger is especially an issue, look to either swap it out as a first option ( a decent two stage trigger from a knackered old rifle a the local gun smiths won't be very much at all ) or if you absolutely MUST re-work what you have, initially get the geometry EXACTLY the same - to within fractions of a mm with the new pieces. You'll know it's right by the new one being just as annoying as the old one. Then SLOWLY re-work the new pieces. remove a fraction of a mm, then re-bed and get a good few shots down the barrel to see how it settles. Then break it down, modify slightly again, then re-bed again get some shots through it.

Having been down this route with a Mk I BSA Lightening, it truely and honestly is an utter pain. If your going to put the time in, re-work a second hand two stage trigger from a better, broken, rifle and jiggle that it.

It will be just as satisfying, just as technical and there will still be plenty to do, but you'll have a useful result at the end of it.


Steve

Offline Stefan Pynappels

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Re: Airgun Trigger Overhaul
« Reply #4 on: July 08, 2009, 03:08:40 AM »
Hi Guys,

Thanks for the replies, what I want to do is somewhere between Stilldrillin and RipSlider. The sear part is made from a sandwich of 3 2mm thick pieces stamped from sheet and rivetted together. The stamped edges are quite rough and polishing seems a little waste of time. I was hoping that machining this part from solid steel, to the exact same size and shape will allow me to polish it properly and give a smoother, more predictable release.

Everything from peashooters to .50 cal is FAC here in NI, so I do not want to alter the trigger unit, but remaking the part in an identical manner from solid steel would not make the trigger unit any different so should not require any paperwork. I had a friend who lost the ejector from his 9mm Flobert cartridged garden shotgun, and the police said he could get a new one made to the same size as the original without having to do any paperwork.

Offline Stefan Pynappels

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Re: Airgun Trigger Overhaul
« Reply #5 on: July 17, 2009, 05:50:24 PM »
Hi Guys,

Got some shop time with Tim (Spuddevans) today and got about halfway through making the part. Thanks for your help Tim, you rock.

Stefan

Offline Jonny

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Re: Airgun Trigger Overhaul
« Reply #6 on: August 17, 2009, 04:15:17 PM »
Whats the score now Stephan?

Can tell you all about triggers having designed and made quite a few one offs. Incidently thats a single stage jobby, no moving sears unless theres a load of creep.