Indians For Guns

Most of local made guns have high tolerances,and that causes twang/buzz from the very first shot.
I belive these twang or buzz have nothing to do with accuracy and velocity as it occur after pellet leave the barrel.
To eliminate that ,I have used flat and round serface of Pepsi/Coke 600 ml bottles.
I cut them in size as per the inner dia of piston and inserted till the last end.One need to check the gap between spring and inner dia of piston which should not be more tham 1 mm.
Generally desi guns can take at least two this kind of sleeves.
The end of the inner most sleeve has to be cut vertically for 4 mm side by side at 4mm intervals and then folded at 90° so that it can anchor with the base of piston.Once the final sleeve is inserted, a metal washer is to be put through the sear rod and then main spring is inserted with proper lube.
A top hat is better option than a washer.
Most of the Desi guns have spring guide OD from 12.5 mm to 13.00 mm.The main spring ID has to befitting with OD of spring guide with very little tolerance.
Having done the above ,I have very successfully reduced buzz of my high power gun but surely could not eliminate it completely.
Till the time the sleeves take the position, you might hear a light scraping sound but over time it will reduce to maximum extent.

Basu

[quote="Basu"
]Most of local made guns have high tolerances,and that causes twang/buzz from the very first shot.
I belive these twang or buzz have nothing to do with accuracy and velocity as it occur after pellet leave the barrel.
To eliminate that ,I have used flat and round serface of Pepsi/Coke 600 ml bottles.
I cut them in size as per the inner dia of piston and inserted till the last end.One need to check the gap between spring and inner dia of piston which should not be more tham 1 mm.
Generally desi guns can take at least two this kind of sleeves.
The end of the inner most sleeve has to be cut vertically for 4 mm side by side at 4mm intervals and then folded at 90° so that it can anchor with the base of piston.Once the final sleeve is inserted, a metal washer is to be put through the sear rod and then main spring is inserted with proper lube.
A top hat is better option than a washer.
Most of the Desi guns have spring guide OD from 12.5 mm to 13.00 mm.The main spring ID has to befitting with OD of spring guide with very little tolerance.
Having done the above ,I have very successfully reduced buzz of my high power gun but surely could not eliminate it completely.
Till the time the sleeves take the position, you might hear a light scraping sound but over time it will reduce to maximum extent.

Basu[/quote]

Hi Basu,
> What you have done is an "Old School" method - It works but its time to resort to a modern method
1. Dismantle your AR
2. Polish the internals of the receiver gently without increasing the ID
3. Polish the piston & if possible get it hard chromed & insert one or two high quality polymer thrust bearings in the front & rear of the piston
4. Fix the adaptor on to the piston & mount a Denil Washer (available from TTI) as this comes with a covered top & does not expose the adaptor's face / ensures proper compression
5. Get a spring kit that includes a top hat & rear guide from TTI
6. Give a diamond finish to the piston sear (U are an expert in this)
7. Apply moly grease to the external & internal of the piston & inside of receiver
8. Ensure that the breech seal is a perfect fit (Neoprene O rings are best)
9. Light oiling of the trigger mechanism is advisable.
10. Assemble your AR & dry cock it with the trigger pressed half a dozen times (this is to be done with utmost care) as otherwise it will cause auto-fire
> Now cock the AR & load a pellet & fire - you may get dieseling initially - but its OK.
> All done - No more vibration or twang - Your AR will be sweet to shoot
Happy Shooting
Briha

Ensure that the breech seal is a perfect fit (Neoprene O rings are best)

Sir,
please tell me the Neoprene O ring size for IHP 35(.22) breech seal, if you have.
(or) the availability at any web store.

Thanks
RamMani,
Karur(TN)

RamMani wrote:

Ensure that the breech seal is a perfect fit (Neoprene O rings are best)

Sir,
please tell me the Neoprene O ring size for IHP 35(.22) breech seal, if you have.
(or) the availability at any web store.
Thanks
RamMani,
Karur(TN)

Hello RamMani,
Pl. PM me your cell phone no. & postal address & I will courier you a couple of seals that are lying spare with me.
You can show the sample to any auto spares dealer or hardware shop & get them.
I'm sure the samples I send should fit your AR - if not get the correct size based on the sample.
Briha

Thanks Sir,

I will send my cell phone no. & postal address thro' PM.

Regards,
RamMani,
Karur(TN)

Just an update
........
Sunsilk 90 ml shampoo inverted tube is an nice alternate of Coke/Sprite pet bottle.
just cut it in two equal parts.
In case a little more thinner sleeve ......one can use AXE shaving cream tube for the same purpose.
In general one sleeve is a must and then based on remaining space , one can decide wheather to go for 2nd sleeve.

Basu

Hello Basu Da and Briha Ji,

Forgive me for venturing into reviving this old thread please! I feel I have a valid query though, and hence my attempt.

One of THE most critical factors to reducing the spring twang and vibration is to ensure a tight (in fact, VERY tight) fitting spring over the Rear Guide. Actually, some experts have repeatedly endorsed that the spring in its natural decompressed state should ideally need to get gently hammered into the guide. As an alternative, when they recommend applying Open Gear Lube /Black Tar for reducing twang, you would notice that they insist on applying it ONLY along the last two-three inches (Charlie DaTuna, Tom Gaylord, Jim Tyler and others)....because that is where most of the vibes originate.
In fact, if this gets taken care of, the spring with its tail pried tight tends to keep and behave straight...of course the front and rear thrust washers and the inside piston sleeves are a great support.

To do this, I trust the use of coke can sheets cut to wrap tight over the Rear Guide OD is a good shimming alternative. If need be, stick it with a thin coat of araldite. Cut grooves at the rear, fold 90 degrees out and make a washer (prefer polymer) sit over and jab the shim at the tail. Just ensure that you end up hammering (not heavily though) the spring onto the rear guide ...of course after you have dabbed Moly over it.

Will love to have your thoughts and reverts on this please.....and pls not miss to critique and trash it if in your experience it is rubbish or inconsequential a job. Will save many from trivial airgunsmithing info.

Warm regards,
Prashant

Its better to use the right spring with ID matching the guide OD. The above DIY works will be justifiable only if there is no other way to rectify the problem in hand.Or you can make a guide matching the piston rod and spring using lathe.

Snugfit guide may add to reduction of twang but if much room is kept between OD of spring and ID of Piston then twang may be palpable.
Sleeves are used to reduce that Gap to minimize the buzz/twang arising out of piston.

Basu