Air Gun Home :: View topic - 850 HPA conversion, fill equipment and Velocity test results

4950cycle · Member

Is it just me or did anybody understand those #s rbva posted ? Question

cw · Banned

It's not you, and no.

cliffspot · Veteran Member

800fps in 22 on CO2 is not possible due to the pressure limits of the CO2 gas. Mine does a hair under 700 on a hot day. But the limits are the inherit parameters of CO2 as a propellant. If there was a bigger port system it would let in liquid CO2 and that would do no good. Roald correct me if I am wrong! I am running bulk too. How many shots you getting off a 9oz fill? I shot about 20-30 I think, put it away and lost count! LOL

H · New Member

What happens to the pellet after 330m/s or supersonic?

AirGunEric · Site Admin

A pellet is not designed to go over the sound 'barrier'- it is a "diabolo" with a skirt- not a fairly uniform/solid projectile like a ball or bullet.

All projectiles of any shape/size get kicked around a bit going from sub-sonic to sonic, then buffeted again coming down from sonic to sub-sonic. If a projectile can hit it's target before dropping back through the sound "barrier" while slowing down, great- but if not it gets hit with two significant upsets- upsets that most bullets can handle reasonably well, but skirted pellets cannot (they cannot deal very well with one destabilization going over the speed of sound, let alone two).

cliffspot · Veteran Member

1400psi is the output pressure, 3000psi is the tank pressure. So a full tank of air is 3000psi and the output from the reg is 1410psi. When the tank drops to 1400psi the output drops to 1380psi...got it? And to get 88fpe from CO2, you gotta shoot your gun with the CO2 tank over the BBQ! LOLO!

broommaster2000 · Moderator

How about 700 FPS in .22, that should be reachable, right?

I'd like to pass that 200 Meter per second. It just would add a little more to the whole darn thing.

cliffspot · Veteran Member

After Roald did the mods on my 850, it just makes about 700fps. Actually chronyed at 690fps with the 14.3 gr pellet. I think it should hit 700 on a hot day. That's about the limit with CO2.

H · New Member

AirGunEric · Site Admin

Not familiar with the term "boat"- "boat tail"- yes- the rounded rear of some bullets which is done to aid in reducing vacuum behind the bullet which slows it down.

Super-sonic airguns basically need a projectile shaped like a conventional bullet- not a pellet/Diabolo shape. Even a lead ball would tend to be less affected by subsonic/supersonic crossings than would a Diabolo pellet.

And yes, the less "waist" on the projectile, the better.

H · New Member

I did not think boat sounded correct but boat tail sounds far more familiar.I guess that all the more powerfull air guns [330m/s + ] would use this type of pellet?

AirGunEric · Site Admin

Pellets of this sort are generally a very "specialized" variety- you can't go to PyramydAir or the like and buy them off the shelf typically. So- what happens? People buy these 1200fps (400-ish m/ps) guns and use off-the-shelf pellets of the Diabolo variety and wonder why their accuracy is terrible.

cliffspot · Veteran Member

Chronyed my 850 yesterday at Sunshine Airguns. Beeman FTS pellets are going @ 700fps, 78 degrees AC in the shop (approx). RWS Superpoints were @ 695 fps. This is with the modded factory comp attached, should add 20 fps without it. Loving this gun more every time I shoot it! Thanks Roald! Took it to a gun shop near my house on Friday, they specialize in Tac guns (AR's, Glocks, snipers, etc..). The owner loved it! Gonna convert them to airpower soon!