Trig­gered!

Airgun World - - Contents -

Tim Fin­ley’s study on the im­por­tance of trig­gers – part one

Here’s a state­ment to kick off this new se­ries: just be­fore the shot is re­leased, the only in­ter­face that should move be­tween a gun and a hu­man is ar­guably the most im­por­tant one – the trig­ger fin­ger and the trig­ger blade. The type of trig­ger has an ef­fect, as well as what the shooter does with the fin­ger.

Let’s get our heads around the two main types of trig­gers found on air­guns; sin­gle-stage and two-stage trig­gers. As the name sug­gests, there is only one el­e­ment to the trig­ger op­er­a­tion with the sin­gle-stage trig­ger. When the sears break, ei­ther the pis­ton in a spring ri­fle is re­leased to com­press the air in the cylin­der, or as with a pre-charged pneu­matic airgun, the ham­mer is re­leased to strike a knock-open valve, and here is where I can con­fuse you. Many air­guns have sin­gle-stage trig­gers mas­querad­ing as true two-stage ones!

TRUE AND FALSE

A true two-stage trig­ger moves sears apart on the move­ment of the trig­ger blade, to lessen the dis­tance the sears have to move, to re­lease the shot, and some sin­gle-stage trig­gers have a ten­sion­ing spring on the trig­ger blade to make the shooter think it’s a two-stage trig­ger. All the first stage does is to al­low the shooter to ap­ply pres­sure to move the trig­ger blade to come to a stop on the sin­gle-stage phase of the trig­ger mech­a­nism, when fur­ther pres­sure ap­plied on the trig­ger will move the sears apart and fire the gun.

Many shoot­ers get con­fused over sin­gle- and two-stage trig­gers; both the real two-stage and the pseudo two-stage trig­gers should have a lighter first stage than sec­ond be­cause that al­lows you to know when you have reached the crit­i­cal point in the fir­ing cy­cle, when ap­pli­ca­tion of slightly more pres­sure will fire the gun.

WHAT’S THE DIF­FER­ENCE?

Re­ally bad trig­gers suf­fer from creep on the trig­ger sears, and the shooter can feel the me­tal-to-me­tal con­tact as the two sear sur­faces scrape over one an­other. Hon­ing or pol­ish­ing both sear sur­faces to a pol­ished mir­ror fin­ish does help a lot with this un­de­sir­able sit­u­a­tion, but a word of cau­tion here; never try to al­ter the orig­i­nal an­gle of the sears. It could de­stroy the trig­ger’s func­tion­al­ity and. even worse. make it un­safe.

For ex­am­ples of a sin­gle-stage trig­ger and a true two-stage trig­ger, I took apart two of my own air ri­fles. A Chi­nese-made B2 break­bar­relled, spring-pow­ered ri­fle gives us a look at a trig­ger on the bot­tom end of the sin­glestage trig­ger scale, whilst my Air Arms 400 se­ries, pre-charged pneu­matic has a su­perb two-stage trig­ger. So it should have be­cause it’s an HFT match ri­fle – and when tak­ing hard po­si­tional shots, a light pre­dictable trig­ger is a mas­sive help in such dif­fi­cult com­pe­ti­tions.

The B2 is a very ba­sic, break-bar­rel airgun, so it doesn’t need a match trig­ger and it hasn’t got one. To jus­tify each type of trig­ger look at the over­all cost of each gun and for what type of shoot­ing it is man­u­fac­tured.

“nicer to shoot, and I think much more ac­cu­rate with even a slightly bet­ter trig­ger”

COM­PAR­I­SON

I was a bit sur­prised when I took the B2 apart to find that the trig­ger sear was made up of three flat pieces of sheet me­tal, held be­tween the sides of the trig­ger blade sec­tion, which was also made from a piece of pressed sheet steel.

I know the B2 is the cheap­est of the cheap when it comes to air­guns, but the crude­ness of the trig­ger came as a sur­prise. It is not a mas­sively in­ac­cu­rate gun at the end of the day, but it would be so much nicer to shoot, and I think be much more ac­cu­rate, with even a slightly bet­ter trig­ger.

The AA400 trig­ger is a true two-stage mech­a­nism be­cause the first and sec­ond stages are pulling the sears apart, but the B2 trig­ger it has one sin­gle part and one spring, and the 400 has four mov­ing parts and two springs. Not to ham­mer the point, but look at how much they cost!

CLEVER DE­SIGN

The AA400 is a clever de­sign; it has an ad­di­tional small lever upon which the trig­ger blade sec­tion presses, with two ad­justable screws.

Once the ac­tion has been cocked and the top trig­ger sear is hooked onto the ham­mer, ap­pli­ca­tion of the first-stage trig­ger pres­sure uses the shorter domed screw on the trig­ger blade sec­tion to move the lever up, piv­ot­ing on pin B. This presses up­ward on the bot­tom of the lower sear sec­tion, mov­ing the sears apart a lit­tle. The trig­ger then comes to a stop and the sec­ond screw makes con­tact with the un­der­side of the small lever.

A very small amount of pres­sure then re­leases the sears and the ham­mer rushes for­ward un­der the spring ten­sion of the ham­mer spring, to strike the knock-open valve and re­lease com­pressed air be­hind the pel­let.

I’ll fin­ish off trig­gers next month, with ad­just­ing tips and more of the hu­man bit, with a few real-world tests thrown in. I

Only the sec­ond-stage screw has con­tact with the small lever; the top sear has dropped and the ham­mer is not held by the top sear.

The Air Arms 400 two-stage trig­ger has four pivot pins; A is the trig­ger blade; B is the ad­di­tional lever to start the sep­a­ra­tion of the sears; C is the bot­tom sear, and D is the top sear. It also has two springs; S1 is the weight on the first stage, and S2 pre-ten­sions the top sear onto the bot­tom sear.

There are now four con­tact points in­volved in keep­ing the ri­fle safe un­til the trig­ger is op­er­ated. The first-stage trig­ger screws onto the small lever, the small lever onto the bot­tom of the lower sear body; the two sear faces and the top sear body onto the ham­mer.

Two air ri­fles with very dif­fer­ent trig­gers.

Newspapers in English

Newspapers from UK

© PressReader. All rights reserved.