.22 vs .25 in a different way (same weight)

Accuracy and energy retention are a function of weight and not size - right? When are you going to shoot them and let us know?

my money is on the .25 because the pellet will be shorter. The twist rate is what comes into play here. Its not the weight of the projectile......but rather the length in relation to its width that really determines the optimal twist rate. Unless the .22 barrel has a fast twist rate ideal for a pellet that long.......which probably none do......the .25 will be more accurate with that weight pellet. That heavy pellet would be good for close shots on bigger game.....like a racoon or something. But no way that 33gr .22 is going to hang with the 33gr .25 unless the gun is designed to actually shoot that heavy pellet. Oddly enough.......if the .22 was twisted fast enough to stabilize that long pellet... it woukd have a better ballistic coefficient. I could be wrong tho.......my knowledge and above opinion is founded in years of powder burners. Still new to air rifles.

nt

This is gonna best interesting. I think with them being launched at equal speed the .22 would definitely get better penetration. In theory they should be as accurate. I'm sure we will find out as more people get them in there hands. I ordered some just to play with and have on hand.

I would think the long .22 might exhibit a stability issue except for one thing... I have never known JSB to make a bad design yet in anything I have tried.

Thurmond

I had the opposite idea, the longer skirt on the .22 might give a better (more forward) weight distribution and better weather-vane stability. Would need to see a cross section view to know for sure, though. And, my estimates are based on using a smooth twist barrel, i.e. slow actual pellet rotation rate.

The winner would be exact king .25 The best accuracy in cal. 22 is jumbo exact or heavy

I'm at work so I don't have access to chairgun but if you can open chairgun it should tell you the Balistic coefficient of the two pellets. Which ever one is higher will be the most accurate.

I have a .22 shooting JSB Monster 25gr pellets at 920fps. I also have a .25 shooting 25gr JSB kings at 920fps. Both guns are absolute tack drivers and BC's are relatively the same everytime I run them. Even though it is a toss up, I have always felt the .22 has a slight edge.

I would think that the BC will determine how flat the trajectory is, the higher BC the more energy it will retain and drop less at longer range. As far as accuracy, if both pellets are equally accurate out of the muzzle, the one that will fly for a longer time in the air will be less accurate because of the wind has more time to act on it, and also the spin rate decreases more which may affect the flight stability.

I don't see the 25g .22 in Chairgun, but I'm guessing the larger diameter of the .25 would create more friction and slow it down faster than the .22. Up close no big deal, but at 75 yards I bet the .22 (given same weight and initial speed) would be moving faster hence more energy delivered. 

nt

Interesting topic. The question is best for long range what? Hunting? Target shooting? For hunting, I'd pick the .25 simply because I think given the same distance, the .22 would have a smaller expansion.

I wish Harry would read this, and comment.

The BC is the controlling factor in retained FPS. While spin rate is important, it pays to remember that pellets are both spin and drag stabilized. The spin rate of any projectile doesn't slow down very much over its flight time, but can nonetheless effect the stability of the projectile. Poor stability can cause the projectile to wobble (and/or nutate) which reduces accuracy and the effective BC.

As a side light... a decade or so ago, Sierra did some measurements on the varmint bullets to see what the reduction in spin rates were. In the case of a 22-250, the initial spin rate was 240,000 RPM. At 100 yards, the spin rate was still over 230,000 RPM.

The smaller caliber for a given weight will normally have a better ballistic coefficient; it has a larger sectional density. 

That said, for wind drift purposes, you are probably better off shooting the pellets between 800 to 850 ft/s than closer to or above 900 ft/s. It is the lower velocity range here that the wind drift is minimized.

However, if your particular rifle seems to settle down with its natural dispersion at some other velocity, then that may be better even though you have to account more for wind.