I'm currently designing an air rifle and am looking for ways to increase projectile velocity without resorting to combustion, modifying the projectile, barrel length or changing max pressure within the container.

I've considered using a De Laval nozzle to increase the gas's velocity, but from what I've researched it would actually perform worse due to the decreased pressure on the projectile.

Thus, I've been looking for some sort of nozzle or other device with no moving parts to aid in increasing the gas's pressure, but haven't found any (poor wording when searching or does it not exist?). Is there such a thing?

Looking forward for answers.

  • 1
    $\begingroup$ I really like the thought of designing something without no moving parts, in simple terms - DEAD SIMPLE. But you removed all the parameters which can be varied like "resorting to combustion, modifying the projectile, barrel length or changing max pressure". And Nozzles are designed to increase gas velocities only. $\endgroup$
    – SRD
    Apr 10 '19 at 1:44
  • $\begingroup$ Probably downvoted as it is a question without any answer... $\endgroup$
    – Solar Mike
    Apr 10 '19 at 8:07
  • $\begingroup$ I'm not sure how air rifles normally operate, but if you used a big gas reservoir and kept the trigger valve open for the projectile's entire trip along the barrel, that might help -- unless it's already done. If you did do that, then you'd want to make sure that the flow from the reservoir to and through the barrel was as free as possible. $\endgroup$
    – TimWescott
    Apr 10 '19 at 15:21
  • $\begingroup$ If you're willing to expand your horizons a bit, you could also use a larger barrel along with a lightweight sabot. Then a larger volume of the same pressure gas could exert more force on the projectile/sabot system. It would be complicated and heavy, and you'd have to work hard to keep accuracy from suffering. $\endgroup$
    – TimWescott
    Apr 10 '19 at 15:24

One way is "dieseling" but is considered a criminal practice in many countries. The idea is to place a dose of petroleum gel into the pellet base prior to ejection.

I do not recommend modification of air rifles because the muzzle velocity is what determines lethality and legal classification of armament type.


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