Pellet Ballistics?

[Ponz]

Air Venturi Avenger .22 caliber at 22 yards

Please explain:

I zero the JSB Jumbo Heavies 18.13gr
Don't change a thing on the rifle
Then switch to JSB Diabolo Hades 15.89gr
No wind

Got that?

The point of impact doesn't go up or down. It goes about an inch to the right.
This makes absolutely no sense to me.

Thanks in advance,
Ponz

 

[LDP]

It doesnt matter if its airguns or firearms. If you change the projectile poi can change in any direction.

 

[Bam86]

It’s got something to do with barrel harmonics. Different velocity, different bite in the rifling, I can’t really explain it, but have seen it a few times. Had it happen with my 17hm2. Sighted one dead on with CCI, Hornsby same weight bullet shot 2 inches left and an inch low at 50 yards. Nice little group. Went back to cci, and it was dead on.

 

[starlingassn]

sounds normal to me.

you never know where 2 different weight pellets will hit.

 

[Ezana4CE]

@Ponz What are the velocities on the two different pellet weights? Have you collected any shot string data?

 

[badger5th]

It just happens... Anything from me is a WAG speculation. Maybe difference in velocity is causing a different drag profile? (WAG). Regards

 

[Mg616]

Pellet voodoo will do that. I had an FX STX barrel that loved the JSB diabolo, but sprayed the same weight Hades all over the target. Tuned it for a while and got it closer but never in the same league as the diabolo. Burned some incense, walked the dog, put in the Hades clone H&N hunter extreme and they were grouping right with the diabolos.

 

[badger5th]

Proper obturation of the pellet skirt is dependent on air pressure and alloy hardness. Some skirts have different profiles which can also have an effect on how much of the pellet is engaged in the rifling. The pellet head diameter also plays into it. Same exact thing happens with muzzleloading CW rifles. Very similar Minie ball designs can shoot very differently out of the same gun. Pure witchcraft...

 

[scottg0814]

With my .25 Maverick Sniper, I noticed that with the JSB Exact King 25.39gn zero'd and then I switch to the FX 24gn, my POI moves an inch or two to the right within 30yds. I was curious about this also but from what I'm reading here, with any change in projectile POI is up for grabs.

 

[Deleted 45061]

Different shapes, sizes, weights.... yeah I would suspect you will not be single hold grouping it. But hey we all must have something to live for, eh?

At least try to match pellet style and weigh up to make it really fun.

Cheers

 

[TheCarFather]

Air guns are very sensitive to ammo changes. I always assumed the 22 caliber jsb heavy 18.13's were exactly the same as the FX 18.1's, but my Cayden has a noticeable change in POI between them. Zero'd for the FX pellets, when switching to the JSB's the POI shifts about 1" to the left at 30yds. I've repeated the test multiple times with the same results.

 

[Ponz]

Pellet voodoo will do that. I had an FX STX barrel that loved the JSB diabolo, but sprayed the same weight Hades all over the target. Tuned it for a while and got it closer but never in the same league as the diabolo. Burned some incense, walked the dog, put in the Hades clone H&N hunter extreme and they were grouping right with the diabolos

 

[Ponz]

Thanks everybody.

Ponz

 

[Healthservices]

I would attribute a lot to spin, weight, and pellet design. Lighter pellet will spin easier. The amount of contact with the rifling will affect how well it spins. The speed the pellet goes will affect the gyroscopic affect

Allen

 

[KitCarson16]

One pellet regardless of the rifle always surprises me. That is the H and N Barracuda 21.14 grain. You would think because it is heavy it would drop. Never does and in fact it will always shoot high . Something about that pellet changes the harmonics of the barrel.

Kit

 

[badger5th]

Chief pellet designer at JSB and us discussing this on this thread...

 

[bigHUN]

Simple to try.
Take one pellet size and shoot it let say 900. Change the speed to lower 850 fps, it will go to R, change it again higher to 950 the POI changes again to L.
Change the pellet to other Brand/size and repeat, the result will be the same.
Add a tail wind, becomes a whole mess.