Is there an optimal caliber for pellet accuracy?

I think I have shot every brand/caliber/shaped pellet from .177 to .357. From my personal experience, the most consistently accurate pellet for both short and long distance would be the 34gr JSB MK2 with its BC of close to 0.052 at around 900fps. Its hard to define "optimal" here, as it depends on the rifle, speed, power and purpose(paper target or hunting) you are shooting. But in terms of optimal efficiency, you can go by BC - the ballistic coefficient. The JSB 22 cal Beasts at 34gr could give the 25 cal Mk2 a run for their money though.



The higher the BC, the flatter the trajectory, the better it bucks the wind, the more optimal it cuts thru the air.
 
.177 will shoot 'straighter' than the others - sort of like comparing .17HMR to .22LR 
While they're very accurate and will travel far, due to their lighter weight, they're more effected by their surroundings.. 
Air/wind, humidity/temp, etc. With .22, they have more of an arc, but, hold their own in the wind better, 
as do the other heavier calibers, but, with more weight, more air / pressure / power is needed to send em' flying..

As mentioned above - BC is a great thing to find out and know when comparing different types of ammo.

🙂👍 

Sam -

PS: I shot .177 for years and years: Multi-Pumps and Springers. 
With PCP, .22 cal is my go-to, and .25 if/when I just want a bit more knock down / destruction power..

The .22 cal are amazingly accurate also. As are the .25s
Efficiency wise - when power/weight factors in, I'd assume that .22 is still the way to go.

I don't shoot anything larger cal than .25, so I won't speak for anything big-bore.. 
Only for what I use, and as of right now, I've only used the .22 and .25 up to 75 yards at my old range.
 
There is a cross over between all calibers. Not just pellets. The fun of is figuring out what works best. I have two 22-250 rifles one shoots heavy 69 bullets one shoots 50 grain bullets. The 50 shoots flat and fast but when you get out past 300 yards you begin to see the physics of a heavier bullet. Frankly I don’t know how the BC compares . If you plan to shoot at 500 yards better use the 69 

i have a 22 and a 25 pellet rifle and they are very close depending on pellet selection. Even at extended distance. I’d pick the one that is the most accurate . From reading the forum the 22 seems to be the preferred. Check what Bob O does with is FX in 22 shooting slugs. Match that and be happy 
 
That is Very Interesting! And I can see where the x-over could come into play!
I can also see where different rounds would act differently as speed, energy, weight, etc. is all going to effect their stability.. 
For me - I only shoot 10/22s, but like to compare different bullet types also.. Lots of different powder loads and grains to choose from, 
so it's actually sort of a pain.. haha

Pellet wise.. I can't wait to start messing around more with my .25 cal. It is a dual cal setup: Both .22 and .25
Out of the box, configured as a .22, it shot HOT. Power was definitely dialed up for the .25 configuration.. 
That said, it just took a bit of trial and error to find that it loved Heavy .22 cal. pellets best.
IMO, if that's the case, and say the best shooting was a 21.14 gr in .22, maybe the .25 gr in .25 should shoot 'close'.. [similar weights]

Obviously more deciding factors involved.. Still, it should be fun finding out.

🙂 

Sam -
 
.177 by far up to 50 yards, maybe 75, but wind becomes a greater concern. It will outshoot a .22 anytime, although the .22s are getting better.. At a 100? Many make all kinds of claims here. I think I would go with a .25. The prime factor, however, is the shooter. You have to do your job. It takes a lot of concentration, breath control, trigger control, and all the other things that the guy behind the buttplate has to do.
 
At 30yards My . 177 guns do tighter groups than either my .20 or 22 guns, but the pellet is smaller so no prizes there. Place a pea at 50 yards and I get just as many hits with all my guns regardless size.

At 100 yards the heavy fatter pellets are better, not only because of the effects of wind but any small imperfections in the .177 pellet will have a greater effect on the stability compared to the same size imperfection on a larger pellet.

Bb
 
As you can see there are different opinions. I don’t think anyone is wrong it’s a matter of finding an accurate gun and the best pellet/ slug you can find for it. And then being able to SHOOT. I shot a lot of years in silhouette competition and I know on any day the best shooter with an average gun would out shoot an average shooter with the best gun every time . That being said I always studied what the good shots did and used figuring the worst Carpenter needed the best tools. 

Study the forum and see what the “good guys”are using and make your decision. The difference in 22 or 25 isn’t going to make or break your day.

You also may want to talk to the air gun tuners they work on them and their opinion may be worth more to you then us pee ons 
 
Depends on the distance and conditions. In good conditions (little to no wind) a .177 will out shoot a .22 out to 50 yards. My best 50 group is with a .177 and is almost half as big as my best .22 50 yard group. When you see folks shooting competition bench rest, you see .177 caliber. That's for a reason. 

Of course, longer distances and more wind would favor the .22 or higher to some degree. 

So, really depends on what type of target shooting one is doing.

Chas
 
Maybe so,"they" want smaller holes;.177 is best ...been winning the Olympics forever....177 is refined,the rifles are refined and the shooters are defined...myself I like bigger holes,butt I am unrefined....and bigger holes are harder to score,just my thoughts...bigger holes need more power to push the pellet.....177 the best up to a point,point being anything can be made to shot accurate.