How to set Zero in a air rifle

[Mack The Knife]

if you know how to put it back properly, i shall have no problems

Sid, most of us know how a screw and screwdriver work. You have probably not done any DIY work to date but now that you have an airgun, I suggest you start learning. It is not rocket science and it is very gratifying to be able to do one's own gunsmithing.

Since Abhijeet wants to have a look at the trigger, I suggest you use this opportunity to let Abhijeet show you how to threadlock the stock screws. Take along some removeablethreadlock, acetone / surgical spirit / alcohol (to degrease the threads), some ear buds (to put the degreaser on) and the appropriate size screwdrivers. I would prefer you guys do the threadlocking business after you finish shooting, so as to let the threadlock set properly. Or at the very least give it 20 to 30 minutes to set.

Also, take along some oil such as 3-in-1 or Singer or even Vaseline. Put a bit on a clean lint free cloth and apply it to the underside of the action before it is placed back into the stock. Do NOT let the oil trickle into the compression chamber aka cylinder. Do NOT squirt oil into the trigger unit.

Abhijeet, it's probably nothing more than an IHP 35 trigger unit with the sear faces stoned, which may or may not have been case hardened. If it's the latter, the rifle is potentially dangerous as the knife edge on the sear will wear off quickly. If so, keep the trigger release pressure higher rather than lower (assuming it can be adjusted), because it is possible to release such a sear without much effort - an airgun going off when the barrel is slammed shut or the rifle is bumped against a hard surface being a common examples.

I'd use this opportunity to run through the gun safety rules as well.

[Pran]

>ith the sear faces stoned, which may or may not have been case hardened. If it's the latter, the rifle is potentially dangerous

Mack The Knife,
Have you ever tried case hardening with a oxy-acetylene torch? I've always wanted to stone down the sear on my 'hard triggered' air rifle but have not done so because I'm not sure how to harden the sear faces again.

Pran

[mundaire]

Abhijeet, it's probably nothing more than an IHP 35 trigger unit with the sear faces stoned, which may or may not have been case hardened.

Rusty,

From an external look at the Rifle and a couple of shots through it at Garg Armoury, I'd think there was more to it than just a stoned IHP 35 trigger unit. For instance there was a trigger adjustment screw in the trigger itself, just where it it begins to curve - this would be a perfectly useless device on an IHP 35 trigger, which directly engages onto the piston rod. It isn't that difficult to engineer a trigger unit that engages the piston rod "indirectly" through the use of levers, I'm just curious to check out the kind of solution this particular manufacturer has employed...

Cheers!
Abhijeet

[Mack The Knife]

Pran, I have never case hardened anything. Ask Grumpy or Mark.

Abhijeet, let us know what you think of the trigger unit.

The only Indian I know who can and has made match quality trigger units is Dr. Shirsat.

[Sid_kapur30]

Shall do so but once i get another rifle with a straight scope rail till den i'll not fiddle around with it

Cheers
Sid

[Grumpy]

Case hardening involves heating low carbon steel to somewhat above its normalising temperature ( something in excess of 760 degrees C ) with a carburising material and then quenching in a oil or water bath. The actual temperature depends upon the composition of the particular steel used. The process involves transferring carbon from the carburising material into the surface of the treated part which becomes high-carbon steel and extremely hard when quenched. It can be done with an oxy-acetylene torch ( acetylene is a carburising material ) but getting a part evenly heated ..... and to the correct temperature is difficult. If you don`t know what you`re doing you run the risk of annealing the part which will cause it to wear very rapidly. The other problem is that when case hardening the surface is only hardened to a shallow depth as the surface is brittle - the `core` needs to be rather more malleable to impart strength - but with a thin component it is possible to harden the whole item which will leave it brittle and liable to possibly fracture in use.
Yet another problem is that unless placed in a jig parts are likely to warp when heated - which will ruin them. It is possible to reheat, anneal and flatten the part and then case harden again but the component will stretch and thin during this process.......and pretty well inevitable be ruined.
I used to do some colour case hardening but for the hassle involved I`d rather pay someone else to do the work.
I wouldn`t bother to case harden an airgun trigger sear.
Stoning a case hardened part is bloody hard work and can remove the case hardening from the stoned surfaces if overdone by enthusiastic amateurs. This, obviously, means that the part will wear more rapidly.......especially if it has a bearing surface against another case hardened part.
Stoning any sear - case hardened or not - can decrease its effective life quite dramatically. When `tuning` the trigger assembly of a competition revolver it is quite usual to replace components annually. Usually the best idea is to very lightly stone the bearing surface of a sear in order to remove any irregularities and burrs. I used a fine diamond dust ( cylindrical ) file. This, combined with operational wear over time will improve the trigger feel and weight.

[dev]

Dear Mack The Knife San,

The trigger isn't the IHP stoned version but a different unit. I suspect that since the locking detent resembles the ball bearing style of the diana, the trigger may also have been 'inspired' from the same.

It has a pretty positive second stage and not a creepy pull thru eternity and then teeth gritting till the release experience.

So far it looks good but longer usage will be required to know how perfect it is.

Dev

[Pran]

Thanks Grumpy. Going by what you've said, I'll refrain from stoning and trying to case harden the sear. I may as well make a new sear from a MS plate and quench it once I'm satisfied with the pressure I need to exert to pull the trigger.

Pran

[Sid_kapur30]

hey am coming home (noida) where have forgotten my phone will call you guys and fix up a scene

Cheers
Sid

[Grumpy]

Pran, your suggestion is a very good one. If you retain the original trigger and use it as a pattern to make a replacement ( or two ) you`ve lost nothing - apart from time and effort - in making and attempting to harden a replacement.
Remember to use low carbon steel and to polish the replacement very finely before hardening. I prefer to use oil for quenching but you need a large quantity - preferably of a light oil - but engine oil will do. You can even use old ( used ) engine oil. You need a large quantity - even for a small part - as you need to reduce the heat VERY rapidly without significantly heating the quenching medium and so the part drops a good distance through the quench in order to cool most effectively. Using old motor oil will probably turn the sear a very pretty blue which, although very soft, is useful as it will show where you use the stone on it after hardening. You can find diamond files in markets or wherever they sell cheap Chinese tools. A 1 cm/1/2 inch diameter file is ideal if you can locate one.

[Mack The Knife]

The trigger isn't the IHP stoned version but a different unit. I suspect that since the locking detent resembles the ball bearing style of the diana, the trigger may also have been 'inspired' from the same.

Isn't this rifle a IHP 35 that was merely tarted up (very poorly, I might add) or is it something quite different altogether?

[dev]

The trigger isn't the IHP stoned version but a different unit. I suspect that since the locking detent resembles the ball bearing style of the diana, the trigger may also have been 'inspired' from the same.

Isn't this rifle a IHP 35 that was merely tarted up (very poorly, I might add) or is it something quite different altogether?

More or less the same but the rifle handles different as far as trigger goes.

Dev

[Pran]

Thanks again, Grumps. Will post pics once I start off.

I plan to do most of the stoning using a bench grinder.Will use a file once I'm closer to the desired shape.

Pran

[Emery]

Hi,

I dont know if there is thread on this topic.

I wanted to set zero on my Air rifle.
how to do that?

Please help.

Emery

[OverUnderPump]

Emery, whats the make of the rifle and the pellet type you are using ?

For example: With a .177 air-rifle at 30 feet / 10 mts, fire 3-4 groups (3 shots/group) on an AR-1 type/TQ-5 type target. Using this you can go about adjusting sights to zero. But then comes the other part,your rifle sights which wouldnt be evident unless you provide that info.

Cheerio

OUP