How much does wind affect pellets in flight?

[ogre6br]

I was shooting from inside the cab and didn't realize how much wind was blowing across the paddocks-- it was a good 8-12MPH cross wind- gusting to 20 MPH.

With a 30 grain Kodiak doing 840 FPS with a full fill- how much would the wind have affected the pellet out to say 50 meters??

Putting aside the fact I'm a shit shot- how much would the wind have effected the field shots??

A bit of back ground so you know the situation.

I was out spotlighting last night and I was trying to use my .25 cal Rapid MK11 for shots normally taken with the 22lr.

I had only been able to sight it in for 20m before this trip and the was a little rough as I didn't have a bench to sight in with- just standing supported post.

I didn't think the little bit of right in the POI at 20m would make that much of difference to it's overall sight in.

How wrong I was.

I missed a shit load of shots yesterday in the early afternoon before we went spotlighting.

I checked the zero at 40m and found I was way off in my sight in at that range 3/4 high and right-- see pic

I adjusted the sight in and got it hitting as close to POI as I could with the Bench I cobbled together at the farm.
This gave me a bit more confidence in hitting things.

That confidence was misplaced. I missed a shit load more rabbits during the course of the night
Closest range was 30m longest was 75+
I wasn't expecting to make hits at the 65+m ranges- but I missed almost all of the shots in the 35-50m range.

any idea why??

later
p

[Yrrah]

[quote="ogre6br"]I was shooting from inside the cab and didn't realize how much wind was blowing across the paddocks-- it was a good 8-12MPH cross wind- gusting to 20 MPH.

With a 30 grain Kodiak doing 840 FPS with a full fill- how much would the wind have affected the pellet out to say 50 meters??

OK here you go, but this is for the worst case which is wind from 9:00 or 3:00 o'clock AND blowing at the nominated strengths over the whole distance which seldom happens unless you are out on the plains/ open ground with no shelter.

Note this is tailored for .25 Kodiaks at 840 fps ( Others can be very different ). Edit: inches deflection ( Vertical Y axis ) for winds in MPH ( Look to the end of each deflection line for wind speed in red ). . Edit: Range in yards along the bottom ( X Axis ).



Other directions of wind have less effect eg from 4:30 o'clock factor about half. Head and tail winds do cause the pellet to go a touch low or high respectively but not much. Head wind from 2 0'clock think left and a touch low so aim right and a touch high etc.

It is a strong wind that makes me aim off by seven inches at 100 yards. Mostly, because of what I wrote above you will not find wind deflecting your pellet as much as that chart indicates.

Now in case others are reading this, your pellets may get deflected differently. This is because I know that Patrick's 31 grain .25 Kodiak has one of the highest BCs out there at something like 0.036. that is what I have input to Chairgun for the chart. Many of the .22 pellets don't have near that BC some are less than half. JSB Exacts are up there at 0.032 or so if shot below about 900 fps and .22 Kodiaks do pretty much as well as their .25 brothers at about 0.034 providing they are not pushed to above Mach 0.75 or 0.80.

By the way, it is not actual time of flight that determines wind deflection for any given range but it is time of flight less the time of flight in a vacuum. In other words it is the Delay time that is critical. I might return to that with some actual air rifle data from my rifles some time........ The best way to figure wind deflection is to spend lots of time on targets actually shooting in the wind. You might be surprised at how interesting it is
Kind regards, Harry.

[Yrrah]

I was shooting from inside the cab and didn't realize how much wind was blowing across the paddocks-- it was a good 8-12MPH cross wind- gusting to 20 MPH.

I was out spotlighting last night and I was trying to use my .25 cal Rapid MK11 for shots normally taken with the 22lr.

............... I missed a shit load more rabbits during the course of the night
Closest range was 30m longest was 75+
I wasn't expecting to make hits at the 65+m ranges- but I missed almost all of the shots in the 35-50m range.

any idea why??

later
p

Well here are some approximate figures for your outfit. I will presume you had a range finder.
You were sighted in a half inch low at 40 m.
Here are your approx drop figures from that 40 m zero... 30 m / 0.66" high. 40 m / 00.00. 50 m / 1.50" low. 60 m / 3.8" low. 65 m / 5.20" low. 70 m / 7.1" low. 75 m / 9.0" low ... all give or take a tad. ... into the wind add up to an inch more at the longer ranges.

Furthermore, if you were following the flight of your pellets in the light of the spotlight, they generally appear to be going to hit higher than what they do. This is because, unless you have made a study of that little silver streak, you tend to lose it a bit when it reaches the apex of its flight and so think it is going high when in fact it has dropped away appreciably late in flight. That feedback can be the source of errors.

I won't guess as to why you missed so many but hope there is something of interest in my response ...... Kind regards, Harry.

[ogre6br]

best I could tell I was on at 40M- maybe a caliber off up or down- but not much more than that.
The BR was cobbled up and as stable as I could make it? So it was the best I could get it to.

using 15 mph I was getting as a minimum 3.0 inches of drift- thats enough for a miss when aiming for the eyeball on rabbits.

I did see the streak in the light and couldn't understand why I was missing short with them being so high- you expl makes good sense.

No was not using a range finder just my mark 1 eyeball and rather slow brain for rang estimation- don't have the $$ to afford a laser range finder.

Thanks again for you detailed response- it makes a lot of sense.

With you saying It was 9.0 low at 75m I wasn't allowing enough in my sighting over for the longer shots.


Is a high power PCP air rifle capable of taking the place of a 22LR in sub 100m spotlighting??


I'd love to spend a heap of time shooting this one in the wind- maybe if I can get independent access to this property I'll be able to set up a bench and do some decnt range tsting.

thanks
later
P

[Yrrah]

..."Is a high power PCP air rifle capable of taking the place of a 22LR in sub 100m spotlighting?? ... "

In still conditions and with a solid rest my rifles, Excalibre, and both BSA Hornets are certainly capable of it but not without a range finder and my elevation knob chart tape. However when I was spotlighting many years ago for freezers anything over 50 metres was a long shot in the sense that 50 pair and even more of rabbits could be shot at lesser distances and in open grazing country in a night. Has something changed?

I have just fixed up my spotlight again so maybe I'll come back sometime to give a real report there. My spotlight is the original small Lightforce 140?? . I would like to have a mini torch that would be effective to 50 metres and be battery efficient. What is the state of the art there now? Will any of the LED lights show up a bunny at a genuine 50 metres?

Kind regards, Harry.

[native hunter]

Inthinks nya need how 2 learn too shooyt.!!!

[ogre6br]

Wolf eyes make some really good lights

I have a 9A with a 220 lumens head in it and i can use that out to 65M no problems
with a spare charged set of batteries in your pocket you have many hours of spotlighting time


http://wolfeyes.com.au/" onclick="window.open(this.href);return false;

just call glenn it's easier to talk to him than to navigate their new website--

Later
P

[Lewis Reinhold]

Wolf eyes make some really good lights

I have a 9A with a 220 lumens head in it and i can use that out to 65M no problems
with a spare charged set of batteries in your pocket you have many hours of spotlighting time


http://wolfeyes.com.au/" onclick="window.open(this.href);return false;

just call glenn it's easier to talk to him than to navigate their new website--

Later
P

Hi P,
They look like nice torches.I need a new bright white light for the workshop plus some new ones for the kids and around the house.I might give them a ring.
Lewis

[chris thomas]

Hi Pat,

No air rifle will ever take the place of a Rimfire for rabbit shooting unless it's some thing pushing 100 + FP.

Sight that Rapid in at 42 m with Kodiaks or 40 with Silver bears. Rabbits to 50 m with most 25 to 50 FP air rifles are no problems as you don't have much windage or elevation to wory about. Over 50m things get harder as that big 31 grain pellet only starting of at 840 FPS is starting to drop like a brick. Velocity with .20,22 or .25 of 900 to 950 FPS makes hits out to 65m with a 40m zero rather easy.

With my Rapid i'm zeroed at 42 m with Kodiaks . Starting at 860 FPS i need to come up 1 MOA to 50m and 3 to 70m/

Use your scope as a range finder . Set up a target at 50m around the size of a rabbit adjust power on scope so target fits into thinner section of duplex your setting might be around 6 x to 8 X . Then when hunting if it fits in it's a hold on or slight back line hold if not it's over 50m and you might use the section of recticle where thin meets the thicker post. You will quickly find aiming marks using you recticle. Can't remember but i think i use the point of the recticle where the thin meets the point of the thick for around 60m and bottom of point for around 70m. This method works well with my rapid .25 and have taken over 400 Rabbits sptlighting with it. But shots over 70m are hard work and night does make it harder working out distances.

Another method i use with the air guns is to use a crappy spotlight with a 30 Watt Globe that throws a wide messy light. I have set it up this way so it's only good to about 50m or so .This way if i can't clearly see my target through my scope i know it's out of usefull air rifle range. No point using my 100 watt power beam that makes a rabbit at 150m look like to sitting on the end of my barrel if i'm only using air rifle's.


Pat I know the Rapids are very powerful air rifle's but are pathetic compared to rimfire even with sub sonics
long shots on rabbits are just hard work with air rifle's stick to sub 50m and have a ball.

Regards Chris