Increasing the velocity of your air rifle - possible?

[Basu]

Dear All,
This is meant for some extra fun and not surely for target shooting.






Basu

[PRITAM PATEL]

could be classified as Fire Arms

I would neither do that.....nor recommend to any one for possible injury

People have achieved much more gain inf FPS using diff. ideas

Damn sure its not safe or legal

Regards

[Basu]

Is there any other way to increase velocity apart from what have been discussed on the forum so far ??
I have witnessed 11 fpe reaching to 23 fpe through the process of detonation which , to my mind ,can not be reached by any other method.
Having said that members are requested not to indulge in dieseling as it may cause injury and can damage the AR as well.


Basu

[Trajeev]

I remember the times when we used to put some Diesel in pellet tins(mostly imported ones) to lubricate & prevent oxidization of lead.Those pellets always gave us increased power for our live target practice. Those ARs are still in very good condition after more than thirty years of use.So I can safely assume that occasional dieseling does not damage the Air Rifles.

[Basu]

I am told , if too much chamber dieseling is done , that bulges the action.
Honestly, I did not notice any such adverse effect while breech dieseling is done.
Again , it is purely for fun......

Basu

[milind]

Dear Basu,
Thanks for sharing innovative video. I also love experimenting with ARs. This experiment surely shows that velocity is increasing but its not consistent. Its perfectly ok for plinking. I know you ar fan of SDB guns, can you post the result using Precihole. (I know you are having all the equipments). just posting data is also ok.

[Basu]

Dear Milind ,
The person in the video is not me.
He has Precihole springer in .22 that I know ,But probably he would not agree to do the experiment with that gun.
However , I will put a request to him.

Basu

[milind]

Thanks!

[GNV]

Once I tried putting primer compound in the transfer port of an air rifle hoping that the super heated temperatures generated when an airgun is fired would ignite the primer compound but it didn't work in my case.

[Master]

I think good old method of replacing with stronger spring may give reasonable increase in velocity. I was unhappy that my Precihole Pegasus 0.177 was not giving specified 16 Joule power output, even with nitro piston. So I tried replacing it with available spring. Some of my finding are given below:

1. Precihole Pegasus 0.177, Spring replaced with Nitropiston.
Gamo hunter 7.56 gr: 736 fps, 12.15 J.
G Smith high speed 9.9 gr: 606 fps, 10.97 J.

2. Precihole Pegasus 0.177, fitted with G. Smith Mod 27 spring and 5 mm preload in front of spring guide.
Gamo hunter 7.56 gr: 870 fps, 17.23 J.
G Smith high speed 9.9 gr: 680 fps, 13.79 J.
The pellets were hitting too high, though not too inaccurate. That's why I removed the preload.

3. Precihole Pegasus 0.177, fitted with G. Smith Mod 27 spring.
Gamo hunter 7.56 gr: 829 fps, 15.65 J.
Accuracy as good as AR with original spring.

[sam 47]

I have done the experiment with precihole Scorpius and I have found that putting singer oil, 1-2 after every 500 shots keeps the power at 11.4 fpe else drops to 9.5 fpe. There is very mild detonation on first shot, but then stabilizes. The velocity drops rapidly from 612 fps to around 585 fps in 3-5 shots and stabilizes there. I use a syringe to put the oil directly into the piston head. If you put 4 drops detonation occurs with strong fierce vibrations and disassembly is required. The force of detonation forces the piston back again, and if you are considerate enough to put a milliliter of oil in the chamber the gun will re-cock. Not only more power but also a semi automatic sans a way to feed pellets
Recocking exp done in model 23 air rifle.
Master, putting a longer and stronger mainspring doesn't always increase power, or velocity for that matter, only cocking effort. I myself and many others here have done the experiment. I asked Tom Gaylord for an explanation and he said that the air in the compression chamber remains same, it doesn't matter after a level, how fast it is compressed, the power and velocity output will remain same. I am surprised that you managed to increase the power of the precihole air rifle, experienced members always said that the power of a precihole cannot be increased or even if increased like 12.1-12.2 fpe.

[Basu]

Dear Master,
I read some where that ID of Gsmith 27 spring fits very tightly with OD of The spring guide ?
Is this true ?

Basu

@GNV - Once I tried to detonate with kerosene oil.But nothing happened..

[Master]

Basuda,
Based on your information only I tried g smith spring. It fits reasonably tightly, but not very tightly. I think it may vary a little from spring to spring. In my case, one end feels more tighter than the other.

Sam 47,
Precihole claims its AR to have 16 J energy. On Precihole Scorpius, which was 0.22, I used to get around 15 Joules. But on Pegasus 0.177 in stock condition, maximum I got was 9.82 ft. lb. (13.31 J) with 7.6 gr G Smith Amateur pellets. With G Smith 27 spring, the AR seems to be reaching its advertised power, though I will have to wait and see if this velocity sustains after 1000 shots. But this proves that it is possible to get this power in Precihole 0.177 if one can find right spring. Somebody can try suitable Titan XS spring and tell us the results.

For measuring the FPS correctly, I have dedicated my fortune in purchasing Cadwell precision ballistic chronograph. I have avoided detonation as far as possible by applying very thin coating of PH supermoly on piston, spring and seal only.

[Master]

I am quoting a paragraph from http://www.gatewaytoairguns.org/GTA/ind ... ic=94485.0
If I am violating any copyright, please inform me or remove the post.

According to rsterne
" I had somebody contact me this morning to ask how to build a .30 cal Springer.... I have never seen a complete analysis of springer designs, but my gut reaction was to tell him to make the swept volume proportional to the FPE level he wanted.... I just had a quick look at a few volumes for some common springers, and if you take the volume in cc's and divide by 3, you get the following numbers.... Individual guns may be a bit higher, but the numbers look pretty close to me....
Crosman Quest / Gamo CFX/Whisper - 49cc / 3 = 16.3 FPE
Weihrauch HW95 - 45 cc /3 = 15 FPE
Weirauch HW80 / Beeman R1 - 57 cc / 3 = 19 FPE
Diana 350 - 71 cc / 3 = 23.7 FPE
Hatsan 125 - 80 cc / 3 = 26.7 FPE
Webley Patriot - 81 cc / 3 = 27 FPE
Hatsan 135 - 87 cc / 3= 29 FPE "

If I am calculating it correctly, the swept volume for Precihole is V = pi*(1.4cm)(1.4cm)*9 cm = 55.38 cc. So by the above reasoning, with superior design and suitable spring, Precihole air rifles should be able to reach maximum of 55.38/3 = 18.46 FPE. So I think we can try stronger spring on precihole, as we are still far from the limit mentioned by Tom Gaylord.

[sam 47]

Master, it is most true that .177 precihole gives lower power , reason why I bought Artemis. I asked Tom about the swept volume also, you see the diameter of transfer port, its incline all has to do with power output, including piston weight, diameter of piston etc.
If i remember correctly, as precihole was testing prototypes, one of the members who was invited by Dr Sirsat said initial models produced 780 fps in .22, and was lowered to conform to the then law of deal wood test. Power depends on design of AR rather than swept volume.
Most manufacturers use the same transfer port for both their .22 &.177 models, but since precihole mentioned outright that their .22 action can't be fitted with a .177 barrel, you can measure the transfer port diameter and see how much difference there is.
But all that would have made sense if the stock rifle produced even 11.5 fpe. But 9.82 fpe is pitiful !!. Why dont you write to precihole for this ? So much for following 12 fpe limit.