Ok. Which theory wins?

Both pellets at the same speed and same wind, and same distance, I'd say heavier pellet is less affected by that wind. Only out to a certain distance till the heavier projectile slows down before the lighter one. Once that happens, I don't know? But then again, out of the same air gun, wouldn't a lighter projectile always move faster?

Lighter pellets, more affected by the wind, assuming both pellets are the same profile, why? A heavier pellet (all other things equal to include same air rifle with the same settings) has a better Ballistic Coefficient. With very short range shots (25 meters or less) the difference might not stand out. But if you are shooting 50 to 150 meters, the difference is night and day. Keep in mind you can mock this up in Chairgun Pro. I have found the theoretical numbers it comes up with aren't too bad of a match for what I measure at the range. 

One other piece of the pie, pellets are more accurate when they are fired at a specific range of velocities. So if the heavy pellet does not reach that velocity, it may prove less accurate. i.e. not all guns shoot the JSB exact king 33.95 grains as well at the lighter 25.39 grain pellets.

" ...Only out to a certain distance till the heavier projectile slows down before the lighter one. Once that happens, I don't know? But then again, out of the same air gun, wouldn't a lighter projectile always move faster?"

If I'm not mistaken, at a certain distance, the heavier pellet would overtake the lighter pellet in both speed and range/distance (also carrying greater energy down range), due its ability to overcome the wind resistance better than the lighter pellet.

See: ballistic coefficient.

Heavier projectiles generally have greater "ballistic coefficient" than lighter projectiles.

" ...Only out to a certain distance till the heavier projectile slows down before the lighter one. Once that happens, I don't know? But then again, out of the same air gun, wouldn't a lighter projectile always move faster?"

If I'm not mistaken, at a certain distance, the heavier pellet would overtake the lighter pellet in both speed and range/distance (also carrying greater energy down range), due its ability to overcome the wind resistance better than the lighter pellet.

Click to expand...

This is a very interesting question that I dont have the answer to. Looking forward to reading replies of those who know more.

"A .25 PCP may be an effective rifle for use on squirrels at 50 yards if the skill of the shooter and the accuracy of the rifle are sufficient.That is not the case of a .177 rifle that shoots lightweight pellets that lose velocity rapidly."

https://www.crosman.com/airgun-ballistics

Ummm?

Previous posts may address this in part:

https://www.airgunnation.com/topic/ballistic-coefficient-change-with-range-velocity-the-original-study-feb-2010/

https://www.airgunnation.com/topic/longer-range-shooting-thinking-aloud-and-putting-into-practice/

https://www.airgunnation.com/topic/responses-to-azs-ballistic-coefficient-questions/

https://www.airgunnation.com/topic/22-vs-25-in-a-different-way-same-weight/

This is one that has us all scratching our heads on theory, ballistics, ballistic coefficient, more drag, less drag, heavier vs lighter, and the list goes on.

I try to use one scientific method.... just shoot the pellet, out of given gun. I'm a math moron, I admit it. Need a calculator for everything, math and calculations and me don't mix. So I don't!!!!

I've tried pellets of every shape, size, design, speed, weight, high BC, low BC, generally, all in .177 at 12 ft lbs. This translates as a 8.4 grain JSB at 800 fps.

Some pellets shoot better or worse with only a 30 FPS change in speed, no rhyme or reason. Others don't matter. Faster some work, slower, some don't. In my eyes, in the long run, it's all just hit or miss, just keep testing.

In 2016, I used H&N Sniper Mediums (8.5 grains) very effectively, coming in second overall and second to Greg Sauve, former World Champion. The initial run of those pellets were awesome in the wind. Batches of that same pellet produced afterwards did not perform the same.

In the end, all we can do is continue to test, test, and search for the perfect pellet, which, like the unicorn, doesn't exist.

Tom Holland 

Good question, don’t really know, BUT: there was recently a post by? Tom or Matt, don’t recall, about lighter projectiles being exposed less amount of time to environmental factors (wind) because they fly faster, everything else being equal. Therefore being more accurate? Will look up if I can. 

Interesting question, so I pulled up ChairGun and ran a couple numbers.

Assumptions:

25 cal, 850 FPS, 10 mph wind at 90 degrees to shooter

25.4 JSB Kings - 12.3 inch drift

Reduced FPS to 750, drift increased to 12.9 inches

Changing nothing but the weight (Left BC the same) and changed the pellet weight to 33.95 grain and returned speed to 830 FPS, the drift is back at 12.3 inches.

Leaving weight at 33.95, and reducing the FPS to 750, the drift increased to 12.9 inches.

I guess that means mathematically, the difference is in the time the pellet is exposed to environmental factors.

So, knowing that nothing actually stays consistent in this sport, only experience will tell you whether the math really works.

Here's one thought though, since no two pellet designs have exactly the same BC, Higher BC usually wins. All remaining the same, the 254. grain has a BC of .0360, so changing the weight of the pellet to 33.95 and comparing to the King Heavies at the same weight, but BC of .0556, the BC is the big difference.

The King with a BC of .0360 drifts 12.3 inches regardless of weight at 830 fps. The King Heavy MK1 with a BC of .0556 drifts 7.8 inches at the same speed, and wind.

The pellets are quite a different shape with the MK1's needing to pack more lead into a small space. BC makes a much bigger difference than weight.

Heavy objects retain momentum or velocity better or longer than light objects do.

It takes less energy to move a light object than a heavy one. ( wind is energy)

Above statements tried and true carve it in stone. BUT !!!! increase the velocity

and all kinds of weird things can happen to the point the impossible can become possible.

With enough velocity ( we are talking about a lot of it ) you could drive a marshmallow through

a brick wall. As objects whether a pellet, bullet or old shoe gain velocity they tend to act like they

are heavier. That is why a lighter pellet going faster than a heavier one can be less effected by wind

than the heavy one with its lower speed or velocity. The time equation simply calls velocity time.

Just a different way of looking at the same thing.. Roll a beach ball slowly by a fan, then faster, the faster

it goes the less influence the fan will have on it because of higher velocity or shorter time of influence. however you

want to look at it. If the velocity's of different weight pellets are the same once again the original ( stone carved ) statement will be true. 

I think the range would come into play too. From what I’ve seen guys that shoot cf long distance, say 1000 yards shoot long, heavy for the caliber bullets. These bullets have high bc’s and retain their velocity/energy better than lighter bullets at the ranges they shoot. Thus they do better in the wind too.

I would think pellets would be the same at longer ranges. I may be wrong though as pellets are at an aerodynamic disadvantage to bullets of this type.

1BadDart Sorry been out of town, Range or distance makes the forces at work and any

design advantage or disadvantage more evident. And yes pellets are the same as bullets

they simply have drag designed into them so this and that shows up quicker and more pronounced.

That's why there is so much interest in slugs with a BC more like a bullet less like a pellet a much

better choice for longer distances or heavy winds.

Love the name, yes it is clearly 1 Bad Dart !!! LoL

I shoot .25cal pellets with my impact the lighter 25grs at 910fps and the heavys 34grs at 850 the heavys shoot better in the wind.

Sonny You apparently don't have enough difference in the velocity's for the lighter to over come

the weight advantage of the other. If you have a 177 where the weight difference in pellets is smaller

it would be easier to make it happen. But even then the wind must be of the right speed, to much

and the advantage would switch back to heavy, too little wind and you wont have enough energy working

against the different weights to produce the desired results. Keep playing around experimenting and sooner

or later you will see what we are talking about.

Laws of physics apply. Momentum was mentioned earlier. However we are changing variables (more then one). Actually a goodly number of variables. Given all things equal the heavier pellet will resist the wind better but if you add in a different muzzle velocity and a different shape and ballistic coefficient it becomes pretty complicated. Quick answer "YES" but you better test. A heavier bullet that doesn't shoot well isn't going to benefit you. Having shot a bunch of rifles at long range I think you are always better off finding an accurate load and going with that even out to 300 or 400 yards. Now if you are shooting out beyond that then it's an entirely different situation. My suspicion is pellets the same. Out to 50 yards shot the pellet that groups the best. If you are shooting 75 to 100 I'd go with the heavier pellets and test them for accuracy.



If it's just wind you are concerned about then you just have to test to find a heavier pellet that shoots accurately in YOUR GUN . Shooting groups in the wind. That's a challenge because the wind is almost never consistent.

Have you completely confused by now? All I can say is with 40 years experience I'm still looking for the perfect bullet.

Basically heavier pellets have longer flight time. But the ratio that which the wind affects it during the longer flight time is less than the added momentum gained from increased weight.

With rifles, I think there are certain priorities decided for projectiles to meet.

1. Has enough terminal force and velocity for terminal damage

2. Bullet arc favours the distance (lighter bullets have smaller arc but it grows faster the further it travels)

3. Flight time is minimized. This is really only important because the target might move (after the shot) or is already in move.



I like the dart analogy.

You have a goal, you need to accurately hit the board and reliably puncture it to make the hit valid.

For this purpose you can easily make assumptions and tests how and what the dart should be like. Pointy, dragged and semi heavy. Same principles apply to ballistics.