Pellet Weight vs BC VS Speed Wind Drift ?

[Shooting Targets]

So maybe you guys can clear something up. I am confused about Pellet Drift from wind vs the weight of the pellet Vs the BC of the pellet ?

Does the BC of the pellet take into consideration the Weight during windy days ? Meaning, you have a .177, .25 and .30 cal pellet traveling 50 yards with a 15mph wind right to left. 

My experience has been the 177 drifts most, the .25 drifts about 1/4 as much as .177 and the .30 cal seems to drift not as much as any of the other cals.. Now I heard the BC from a .25 heavy is better than the BC from the .30 cal. Would the wind drift be less on the JSB Monster Heavy .25 vs a standard 44 or 50 grain .30 cal ?

I am trying to take everything into consideration in air gunning long distance. From what I have been reading people say the .25 is the way to go for bench rest, but does this mean under less windy conditions or with a shooter than can Wind Dope extremely well ? Taking into consideration what about the .357 pellet ?

Any input would be great ?

Jay

 

[Guest]

While you can take all you've read into account your barrel and pellet speed is what determines how much drift occurs in the wind. What I'm saying is don't trust the computer. Go out there and shoot in the wind. A pellet/slug that is dead on at your given range on a calm day may be unpredictable in the wind, while then next best, or even third best round on a calm day may be predictable in the same wind. As I said before don't trust whole heatedly what you're told and go out and test for yourself.

Also and this is not be harsh or rude or in any other way hurtful but if you can't tell the difference perhaps you need to improve your skills or find a better rifle for you. again I'm not saying this to be mean or hurtful or even troll but I can tell you from experience what I thought I knew about shooting four years ago isn't close to what I know now as I've shot other peoples guns and in matches. Knowing that I was nearly ignorant when I took AG's seriously till now I know that my knowledge is even less now and will continue to learn and change my outlook moving forward.

 

[Michigander]

Maybe I can help. The classical formula for wind drift compares projectile travel time from muzzle to target in air to that in a vacuum. The factors affecting wind drift are BC and velocity. At airgun velocities, higher BC and higher velocity produce lower wind drift. Pellet mass does not independently influence wind drift because BC already takes into account the effect of pellet mass.

​However, BC is not a function of pellet alone, but of pellet and rifle combined. This is because both rifle and muzzle velocity affect pellet stability. The theoretical BC of a given pellet will only be achieved when it is fully stabilized. Unstable pellets will have reduced BC, and to make matters worse, when stability is not achieved BC is usually highly variable, leading to variable wind drift and poor accuracy in windy conditions. This is why, as John states, it is necessary to experiment with each rifle/pellet combination to determine which performs best in windy conditions. I have had the same experience he relates, where a pellet that gave phenomenal accuracy in still conditions, just would not do well in any kind of wind.

​As for directly detecting pellet instability, we have all seen slow motion videos of wobbling or spiraling pellets heading downrange, and that would be one way to go about it. Another method I have found useful is to measure pellet velocity at 50 yards using a chronograph. Velocity variation at 50 yards that is much larger than velocity variation at the muzzle can indicate poor pellet stability.

Chuck

 

[Shooting Targets]

Guys much thanks for the responses.

 

[fpgt72]

"Michigander"Maybe I can help. The classical formula for wind drift compares projectile travel time from muzzle to target in air to that in a vacuum. The factors affecting wind drift are BC and velocity. At airgun velocities, higher BC and higher velocity produce lower wind drift. Pellet mass does not independently influence wind drift because BC already takes into account the effect of pellet mass.

​However, BC is not a function of pellet alone, but of pellet and rifle combined. This is because both rifle and muzzle velocity affect pellet stability. The theoretical BC of a given pellet will only be achieved when it is fully stabilized. Unstable pellets will have reduced BC, and to make matters worse, when stability is not achieved BC is usually highly variable, leading to variable wind drift and poor accuracy in windy conditions. This is why, as John states, it is necessary to experiment with each rifle/pellet combination to determine which performs best in windy conditions. I have had the same experience he relates, where a pellet that gave phenomenal accuracy in still conditions, just would not do well in any kind of wind.

​As for directly detecting pellet instability, we have all seen slow motion videos of wobbling or spiraling pellets heading downrange, and that would be one way to go about it. Another method I have found useful is to measure pellet velocity at 50 yards using a chronograph. Velocity variation at 50 yards that is much larger than velocity variation at the muzzle can indicate poor pellet stability.

Chuck

This is how I killed my first chronograph. The differences between pellet speed is really something that you need to look at, and IMHO gets too little coverage. The formula used to calculate FPE using numbers a foot from the end of a barrel is useless unless you are shooting a critter a foot from the end of the barrel.

Different pellets slow down at different rates over different distances. And the alloy pellets really loose speed quickly.