.22 rim fire vs .22 air gun

[soundchaser]

Please excuse me if my question seems uninformed... that's because I am!

Why does a .22 rim fire, (say a short) deliver so much more ft/lbs of energy than a high velocity .22 pellet propelled by air. The overall fps is close as is the grain of the projectile, yet the impact is 4 times as much.

EXAMPLE: 29 grain bullet @ 1045 fps with 70 ft. lbs VS 28 grain domed air pellet @ 800fps with 18ft. lbs.

 

[IMagius]

Those 200 fps will make a difference - that's over 20% difference in velocity, and major contributing factor to terminal ballistics. Also, I imagine the BC is very different for those two bullets as well.

I've never done the math on it, but on initial looks, I'd say perhaps one of your numbers is in error. Either that or (as is more likely) I expect the ft'lbs of energy "graph" is not a straight line as muzzle velocity increases.

fuond this after a quick search ... h t t p : / / w w w . cruffler.com/BallisticCalculators/BallisticCalculator.shtml

Checked a few online ME calculators ... and a 28gr projectile @ 800 fps is actually closer to 39ft/lbs of energy - a 29 gr at the same speed is 42ft lbs
and at 1050, the 28 is 68 ft/lbs and the 29 is 71 ft/lbs
Just 1 grain does make a measurable difference. And a 20% drop in velocity equated to an almost 50% drop in energy.

 

[Pneumaniatic]

Most airgun pellets are not real heavy. Figure mid weight pellets are about 14-16 grains. Heavy pellets ~20 grains ish. There are heavier ones like the Eun Jin but not very common. Most PCP's cannot propel these as fast as powder .22's, so not as much FPE, and you don't want to push them past the sound barrier anyways.

 

[cam1936]

Ke=(1/2)mv^2

velocity is getting squared. Meaning if you have 2 pellets of the same weight that 200 fps makes a big difference.

 

[ea187]

your numbers are a bit worng but the shape and BC of the projectile make a difference.

 

[Kryogen]

the .22 pellet is not anywhere near 28 grains. The 22 rimfire bullet is way heavier. Thats why.

Its more like 12-18 grains.

There are some heavier pellets, but velocity will decrease, so energy will decrease.

.22 rimfire are usually 40 grains.

 

[unicorn gravedigger]

Most air rifle 22 ammo is in the mid teens as far as grains go, some tip the scales at 20+gr, I think your off on your 22 air rifle ammo, if I'm wrong then name the brand.

 

[sirtaco27]

Yes! We are talking about air rifles and now I don't have to start a new thread. I've interested in air rifles for a while ever since a shot a air rifle in .50 (it was quackenbush I think) and the rabbit I shot went down hard. What would be a good starter?

 

[Kryogen]

Yes! We are talking about air rifles and now I don't have to start a new thread. I've interested in air rifles for a while ever since a shot a air rifle in .50 (it was quackenbush I think) and the rabbit I shot went down hard. What would be a good starter?

you should start a new thread in the air rifles forum

 

[SoBored]

the .22 pellet is not anywhere near 28 grains. The 22 rimfire bullet is way heavier. Thats why.

Its more like 12-18 grains.

There are some heavier pellets, but velocity will decrease, so energy will decrease.

.22 rimfire are usually 40 grains.

That's what I was going to say, a lot of pellets for 22 are around 14-15 grain I find, unless you start buying the specialty ones like JSB heavies which are still only around 18 grains.

 

[Grizzlypeg]

14-18 grain 22 cal airgun pellet at 950 fps vs 36-40 grain 22 rimfire at 1400 fps. Huge energy difference.