Synthetic washer seals the area more efficiantly than leather even if it is little drier. Secondly the co efficiant of the synthetic washer is much less than leather so that it drags less.
The efficiancy of spring powered airgun is dependant on following facts.
1- size & surface finish of compression area. Larger the area, more swept volume of air but spring size also has to be increased to utilise extra air available.
2- diameter, length, design, surface finish & placement of transfer port. Normally transfer ports in straight line to piston's axis give maximum performanance. That is why Diana 52 / 54 are more powerful even after having swept volume similar to many break barrel airguns.
3- Minimum or no lekage of air by means of more flexible sealing materials. But at the same time we have to take care of friction because the piston is compressing air while moving forward & at great speed. Any drag by means of scratches on cylinder walls, piston head, spring housing, spring guide or piston washer material with higher coefficiant of friction can reduce the performance of an airgun.
Another thing to keep in mind here is that as piston is moving forward it's front surface is expanding & sealing the air in front of it which is getting hotter due to rapid compression. Temperatures can reach upto 500 deg. centigrade for a milisecond but that is enough for changing any material's atomic structure & eventually the outcome will be different if the material used is not able to withstand these sudden changes.
4- Air sealing by pellet skirt. Pellets used should be of uniform size & should be little oversize to the bore. May be oversized to the bore by say about 0.02 to 0.05mm to achieve perfect seal. Pellets should not be seating flush with the bore by simply inserting but should have to make you work them push with thumb to be flush with the bore.
This is equally important because as you can see that pellet is fired by compressed air. To achieve maximum compression any hollow area has to be perfectly sealed from all the sides. While firing an airgun piston on it's forward travel is gathering available air in compression area for first 2/3rd of it's travel stroke & in the last 1/3rd stroke it is pushing the projectile from it's seat. Furthermore the air behind projectile pushes it out of barrel. You must have noticed here that air is being compressed only till pellet is in it's seat & thereafter air is trying to expand in additional area of barrel while travelling behind pellet. So no compression once pellet has left it's seat.
Therefore any single change in this chain of compression area, transfer port, spring, piston washer, lubrication, pellet size can have drastic effect on overall performance of an airgun. In general our Indian manufacturer have never thought about or applied any of the points mentioned above. They are simply interested in making maximum profit with minimum efforts.
You may improve upon your factory made airgun by improving upon above mentioned points. I have had improved airguns with as much as 300 ft/sec difference over a factory made IHPs & Hesbees Cannons in the past. Besides these there are many more aspects to consistant & smooth shooting accurate airgun. I will be sharing it here whenever possible.
pkjeetesh";p="64370 wrote:Manish..assuming that everything else remains the same in the new IHP and only a synthetic washer is used...why would it give increased FPS?
