Is faster always better in the wind? New slug info page3

@hoople, thanks much! This is a very interesting and eye opening topic, and flies against the face of logic. But physics is physics, no two ways around that. 

Funny story that relates to this topic. At RMAC, I was walking around and looking at the Pro Class shooters and what ammo they were shooting, with which gun and at what speed. One of the top shooters was talking to another about how he was having such a hard time with the wind, and that he'd never shoot .22 RD Monsters again at one of these 100 yard competitions. Now that I know what I do, and that science backs it up, it turns out it wasn't the ammo that was his problem. The BC of the .22 RD Monster 25.4 grain pellets is better than the BC of the .30 JSB Exact 44.75 grain pellets! He was just having a very hard time reading (and timing) the wind, and blamed it on the pellets. FYI, everyone had a hard time with the wind, and it was howling in Utah at RMAC for a few of the relays. Some guys read it better than others, and some guys also got luckier than others with guessing when the wind would or wouldn't shift...

Thanks @edosan. Remember, we are not talking accuracy or precision here, just wind influence as related to pellet speed and BC. Perhaps your guns are more accurate at the higher speeds (1000 FPS?), and that outweighs any performance benefits of 950 FPS and less with regards to wind deflection. My assumption is/was that most guns (other than ST barrels) are pretty much just as accurate at 850 as at 950, so in that instance anywhere in that band is fine. I know for a fact that my old .30 Bobcat Mk2 shooting JSB Exact 44.8 grain pellets at 880 FPS is just as accurate as any gun I have shot or have seen at EBR or RMAC... Now if I could only shoot as good as you, or Alvaro, or Claudio... Its interesting just how often our "instincts" are totally wrong...

The MATH:

The math behind the physics, for all you nerds and geeks like me that like to see "proof" of this... What this basically proves mathematically is that the "lag time", who major influence is a pellet's BC is the significant influence on the amount of wind drift.

Its called Didion's Equation, shown at the bottom.

Didion's Approximation is called the "Delay Lag Theory" as explained in the Hard Air Magazine article quotes above. Given only the Drag coefficient and pellet dimensions, Deflection cannot directly be calculated. However, if the actual Flight time can be measured or calculated, then to calculate the Wind deflection is quite simple. 

The term (t-sy/v0) is the difference between Flight time in Vacuum and actual Flight time, or the "Lag" time.

Didion's Equation derivation link

Gravity is an ATTRACTIVE force, not REPULSIVE... The EARTH pulls you towards it. The easy explanation is that it is one of the four types of forces, including the Strong Nuclear force, the Weak Nuclear force and the Electromagnetic force. That's probably what you learned in High School. One of the intermediate explanations is that gravity is described by the general theory of relativity (proposed by Albert Einstein) which describes gravity not as a force, but as a consequence of the curvature of space-time caused by the uneven distribution of mass. That's about as far as I go. There are more modern explanations based on particle physics, quantum mechanics, and quantum field theory, but that's over my head...

@crusher, good point. I think that shooters are still having a hard time wrapping their brains around the scientific fact that the time the pellet spends in the wind has nothing to do with how much the wind affects the pellet, and is almost solely dependent on the BC of the pellet at that speed... 

It is so counterintuitive that even after reading the logically presented and scientifically proven explanations, a lot of shooters don't buy it... But like I said, physics are physics. Just because everyone once said the world is flat doesn't mean that it is...

You have Strelok Pro, so try this. The algorithms in Strelok are based on calculations similar to the above. Take one of your set ups, like your .30 RAW. Look at the main screen, and add a wind speed, say 10 MPH at 90 degrees and 100 yard distance. Leave your JSB Exact 44.8 gr. pellet speed where it is (860 FPS?), and BC at probably around .042. Hit calculate, and see how much horizontal (wind) drift there is in inches and mil. Now go ahead and input 1000 FPS for the speed, and change nothing else. Hit calculate. Surprise! Its no better, in fact, its probably worse...

Thanks Jimmy. Don’t forget the .22 cal RD Monster, whose BC is also higher than the .30 cal 44.8 grain pellet. It’s BC is about the same as the .25 Heavy. I think it’s interesting and pretty cool all these shooters jacking up their Impacts to higher and higher power... but it has no real world benefit on the bench. And that’s not in my opinion, it’s fact.

I’m a potential convert to slugs for shooting over 100 yards. The wind performance is potentially so much better that it’s hard to ignore, as long as accuracy holds up. I have a sampler pack of various weights in .22 from D-Rig (Varmint Knocker) that I’m going to be testing in my .22 EDgun R3 Long later this Summer...

Here is a though ... let's say the twist / barrel spin is to the right , so the pellet will spin / rotate to the right @ high speed, more spin + wind in the same direction = more drift, but if the wind goes to the opposite side we should see actually less drift... so the more the pellet rotates, will drift more if the wind goes in the same direction, but less on the opposite? do I make any sense? jajaja

Just thinking out loud here

Click to expand...

I think you're probably correct in your statement above. However, if you plug in the numbers at 100 yards to Strelok or Chairgun, the difference comes out to .1 mil or less, which is insignificant to any actual drift caused by wind.

I've thought about this, and the reason I posted, and the views I wanted to get across are these points:

1. If you're "pumping up" your gun because its fun to tinker and experiment, or you want to shoot slugs faster, or shoot larger heavier slugs at a good speed, then more power to you! (pun intended ). But if you're doing it because you feel that faster will make your Benchrest gun better at 100 yards, you're doing it to make yourself feel better, and not for any rational technical reason. In fact, going up to and over 1000 FPS shows detrimental wind performance compared to 900 FPS.

2. If you're looking to get into 100 yard Benchrest, and don't have $2500 for an Impact or Daystate, you can still be competitive as long as your gun can shoot higher BC pellets over 850 FPS, to about a max of 950 FPS and can shoot close to MOA in calm conditions at 100 yards. A good used EDgun R3 Long in .22 or .25, a Kalibrgun Cricket in .25, a Taipan Veteran Long in .22 or .25, or even a used .25 Bobcat/Royale or .30 Bobcat/Boss would be competitive and cost you around $1,000. Any of these guns when tuned properly, with practiced shooting skills can shoot MOA at 100 yards. You also don't need a telescope on your gun, 20X is more than enough...

3. If you're new to this game, don't be intimidated by all the $3,000 guns with $4,000 scopes. Good tuning, proper pellet selection, and practice practice practice count far more than having fancy and expensive equipment. I'm not saying go buy a Gauntlet and a UTG scope. But any of the guns above in section 2. with a decent $300 scope can be competitive. How do I know this? If not for making a critical mistake that had nothing to do with shooting skill, (I only shot 4 pellets in one target instead of 5) I would have won the Saguaro Classic this year with a $1200 .30 FX Bobcat and $300 Hawke scope against many $5000+ rigs...

4. Did I say practice? Don't practice all the time in calm conditions and then expect to do well in blustery windy conditions. The only way to get good at shooting in the wind is to... shoot in the wind. Lots! And while you're at it, give yourself the biggest advantage by shooting a high BC pellet at between 850 and 950 FPS. Caliber doesn't matter. .30, .25, .22, as long as the pellet is a high BC pellet, you're good to go...

True story: I encountered a shooter at one of my recent 100 yard BR tournaments that did really well, finished in the top 3. And yes, he obviously has some money since he has a custom .30 RAW, and a Nightforce ATAC-R scope. But the funny thing, he kept telling everyone, over and over again, how he'd only been shooting for the past eight months. But its what he didn't say that was important. He was a member of the shooting club, and he had shot at the same range, everyday, numerous hours per day, for the past 8 months with that gun. His "measly eight months" experience was far more than most shooters with actual jobs get in five years... Oh, and one more thing. Skill and experience can make up for a lot. The winner of that tournament also shot a RAW with a very good scope. But he shot .22 caliber, and used JSB Exact 15.9 grain pellets, a low BC pellet - at 100 yards - in the wind! Things that make you go hmmm...