CUSTOMIZATION OF .22 AIR RIFLE

[dwipen]

I am new here but its nice to find like minded people.
I am in the process of buying an IHP-35 (.22) and modify.
I owe a model called Markxman-35(.22) which I purchased in Guwahati. The gun has good power but some lackings

(1) proper gun sight
If the gun sight has more height then more parallax error.
Solution: Keep the height of gun sight as low as possible.







(2)the barrel diameter in its rear end is exactly .22" (5.6mm)
Most of the pellets have slightly larger diameter at the ends (greater then 5.6mm) for air tight. But this also pose problems as it changes the shape of the pellet while closing a break barrel air gun and hence aerodynamic problem as the pellet is no longer symmetric about its axis.
Solution: Slight drilling (with caution) of the rear end of the barrel.






With all these modification now my gun is more accurate and it seems I never miss the target.
Next I will mount a scope for more greater accuracy. Soon I'll post my engineering and pics.
Please post your comment and suggestions as this is my first post.

Thank You.

Dwipen Baro

[hamiclar01]

Will it break your heart if I tell you that the pellets which group the best are the ones that fit the tightest?

Which probably explains why the air arms diablo (for example) in 4.52 in 0.177 or 5.52 in 0.22 is actually harder to come by?

[brihacharan]

Will it break your heart if I tell you that the pellets which group the best are the ones that fit the tightest?

Which probably explains why the air arms diablo (for example) in 4.52 in 0.177 or 5.52 in 0.22 is actually harder to come by?

Hi Guys,
> Yes its true - the pellets that fit the tightest are the ones that group better - no leaks, no energy lost.
> Infact a friend had his BAM40's spring broken because of an ill fitting pellet. The gun was tuned to super perform.
> What caused this was, the pellet was stuck angularly in the breech which simulated a 'blank fire' and the resulting resonance broke the spring!
Cheers
Brihacharan

[Big Daddy]

What Dwipen is talking about is the chamfering of the breech. Jeetesh helped me on that in my gun. What Dwipen would have done is not to affect the tightness of the pellet fit. The pellet would not have sat properly, mostly at a slight angle. When the pellet is loaded, the barrel shut and then opened you could see the skirting of the pellet is damaged, crumbled inwards. Care has to be taken during the chamfering process. Pellets still sit tight in my gun. I have not met Dwipen but from my experience this is what I assume. And about the BAM 40. Maaaan!!! That’s a real nice gun to shoot. The trigger is just great and the aim amazing.

BD

[dwipen]

Big Daddy's explanation is correct. Moreover as the barrel is 5.6mm very very slight drilling does not cause air to leak out, just the exposed portion of the pellet in the rear is reduced thereby making it less deformed as the break barrel air gun is closed..

-- Mon May 31, 2010 11:41 pm --

All imported air gun do the chamfering of the breech. One good example the barrel of Webley Xocet 0•177 calibre break barrel air rifle

[dwipen]

Can any IHP-35(.22) user tell me about "chamfering" of its barrel..

[brihacharan]

by dwipen » Tue Jun 01, 2010 10:13 am
> Can any IHP-35(.22) user tell me about "chamfering" of its barrel.

> Hi Dwipen,
> What do you mean by chamfering of the barrel? Or do I presume you are referring to 'Crowning' of the barrel?
> Chamfering means to bevel the edge or corner.
> Crowning is done when the barrel is cut at the end - the edges have to be smoothened by bevelling - this is necessary to maintain the accuracy of the gun and prevent lead fouling at the barrel's end.
Cheers
Brihacharan
PS: From the picture posted that shows the breech - are you referring to drilling to 'countersink' the breech aperture to ensure that pellets seat properly - in case the pellets you use are oversized and you need to push them with force?

[fantumfan2003]

No he means the breech end not crowning. Dwipen the ideal chamfer is rounded. You need to get a book on springers called The Airgun From Trigger To Target by G.V. Cardew

Trust me you will know a lot more once you are through reading it.

M.

[dwipen]

thanks fantumfan2003

[spslfa]

hello friends

what about the solution for the first problem; shortening of foresight? will it improve the accuracy?

good shoot

suresh

[dwipen]

Yes,spslfa, as it would reduce the parallex error.
My new modification for 2k




-- Thu Jun 03, 2010 10:14 pm --

A very simple rail... need finishing... and color...

[spslfa]

hello
does shortening of front sight work for IHP 35? also, how you made the rail to mount the scope? what you did exactly? did you gas weld it?

good shoot

suresh

[pkjeetesh]

good job Dwipen.....okay friends....breech end crowning is tricky..if it is not done correctly..you have a ruined rifle...'tight fitting pellets' do we mean - the head of the pellet goes in but the skirt doesnt' ....it sticks out ..prominently?...then when you close the breech, the pellet gets smashed?...and accuracy goes for a six!...THAT IS THE CASE most of the time....below is a picture of my IHP35 .177...the breech is crowned carefully by means of smearing 180grit wet lapping compound over a correctly selected metal ball welded onto a steel bit, the tool is then chucked to a standard drilling machine and the breech area is ground....ever so carefully, until the desired pellet seats properly and the skirt is square with the breech face....the pellet and the fit, by trial and error you will ensure will not begin to leave the barrel before the piston hits TDC....you should hear a solid ''thwack'' ...thats when you know youve' got it right...the Webley Xocet breech seal is damaged because of barrel bolt play...the seal is coming down on the top edge of the receiver when the breech is being closed...no numbers here but the breech seal should be 'just' proud of the barrel face..i used a silicon 'O' ring as you can see in the picture...to arrest side play...(red arrow)...steel washers were used...is everything making sense now....



reg

pkj

[Big Daddy]

Very much PK . Thats learning!!!And Fantumfan, thanks for the tip on the book. Going to hunt for it.

[dwipen]

hello
does shortening of front sight work for IHP 35? also, how you made the rail to mount the scope? what you did exactly? did you gas weld it?

good shoot

suresh

Yes (look for front sight in other guns in web). Just two properly aligned iron wire was gas welded.