"Wind” is whatever factors cause 200 yard groups to be greater than twice 100 yard groups, and includes wind drift and mirage. ("Wind” becomes exponentially more important as range increases; thus this speaks to ranges of ~300 yards or less.) Calculations of the effect of “Wind” on group size show that with no “Wind", 5/100 (5 shot 100 yard), group size would decrease 4%, 10/100 5%, 5/200 13% and 10/200 16%. “Wind” is not a great contributor to inaccuracy. “Goal to Go!” by Warren Page, 1957 Gun Digest pg 83 “”¦In the finest accuracy shooting ever done by a large entry, that at Johnstown last Labor Day, in the hundred-yard 10-round matches, 28 of 148 riflemen averaged less than half a minute of angle. But for the fifty-shot series at twice this yardage, only two of 146, Sam Clark and myself, could stay under the half-minute mark. At 200 even the top ten shots averaged almost 30 per cent bigger groups, relatively, than they had at the shorter range, and among the less inspired trigger-squeezers the fall-off was far greater”¦.Reason? Sighting problems, wind and mirage, which are essentially human rather than equipment problems. Of this inter-related pair, wind drift is far less a bogeyman to the accuracy bug than target displacement by mirage. I can remember only a few shoots (and they were conducted in minor gales) where the sights were free of mirage waves, yet bullet paths were bent and the groups enlarged by wind alone”¦. As a source of accuracy error, most of us cranks consider mirage four or five times as wind in normal quantities and velocities." Page's article reinforces my faith in the calculations and the following conclusions: Some of the effort to measure (wind flags etc.) and compensate for wind drift might be more productively spent on other terms of the accuracy equation. (I cannot emphasize enough that compensation for wind drift is feedback-free; the shooter receives NO information about the efficacy of compensation.) Some/much of the effort to design bullets with less wind drift = higher ballistic coefficient = longer, heavier, smoother, pointier are not productive. Pope style multi-groove base band flat point bullets? Cast bullet design for shorter range applications is sometimes aimed, with tunnel vision, at beating the wind-and the wind is not much of an adversary.
"Wind"
- 4.6K Views
- Last Post 28 February 2014
Joe, Excellent and thought provoking post. You have shown again that interesting things can be learned about cast bullet shooting by using numbers. Your rational approach of assessing the probable effect of wind and mirage by comparing group sizes fired in competition at 100 and 200 yards and from that estimating the probable effect at 100 is clever and I have never read of anybody else doing it.
I think a lot of competitive shooters will agree with you that mirage is usually a bigger problem than wind.
You make a good case that the wind problem probably isn't as bad as most of us think and we should worry less about it. One thing that probably inflates the effect of wind in our minds is that we often blame wide shots, even vertical ones, on the wind -- perhaps because we would rather blame nature than ourselves. Human nature at work?
However, I think you may overstate a bit the insignificance of wind. As someone who has tried CBA competition with bullets with truly terrible ballistic coefficients (225415 and other blunt short 22 bullets) I believe I have seen clearly the SIGNIFICANT disadvantage of such bullets, especially at 200 yards.
Designing and shooting a 22 bullet with “higher ballistic coefficient = longer, heavier, smoother, pointier” significantly improved my 200 yard scores. Of course some of that could be in my head from assuming those bullets would drift a lot less. However, I think it is unlikely that Pope style flat point bullets are going to make a comeback.
John
Attached Files
The above is not to suggest that the wind drift calculations performed by the many ballistics programs available are incorrect. These programs, the simpler ones, assume a constant wind velocity-a vector quantity including both speed and direction. Wind velocity may vary over the range, wind flags testify to this. Then wind drift is the product of the sum of these velocities, and it may very well be that that sum is commonly less than is estimated. There's an intersection of probabilities, weather and ballistics here that may explain the lack of connection between group size and “Wind” compensation.
Attached Files
"Thermal Inversion” is one of those dream words that pop up occasionally and will get the heart of an old marksman like me popping at the range and trying to beat some old long lost friend. I shot my lifetime best during a thermal inversion with complete calm wind. Those are eerie days with a rifle!
Gary
Attached Files
Saturday was 40 degrees and windy at 20-25 mph. I took my 6ppc with 80 gr Eagan bullet loaded to about 2300 fps. Alfred E. Newman went with me for his first time to shoot. I'm no top notch shooter, but I informed Al that the wind would blow the bullets around and he should watch the wind flags and wait for a “condition.” He only replied, “What, me worry?"
Al shot, not paying much attention to anything and he said he held on the center of the bullseye every time. His groups: 2.025, 1.315, 1.840 and 2.250, for an agg of 1.857.
I tried to wait for conditions, and shot when I thought it was about the same. I, too, held in one place on the target. My groups: 0.700, 0.600, 0.960 and 1.120, for an agg of 0.845.
This made me wonder about the wind effect and how it shows up in the statistics. It would seem to me that people who shoot in the CBA National Match would not be first time shooters and that they would know a little about reading wind flags. They are aware of the conditions and try their best to compensate for them. Their groups should be smaller that an inexperienced shooter.
Attached Files
Joe,
I don't have a horse in this race. I watch the wind flags only for “sameness” of conditions. Only if I am running out of time will I go to the sighter target and take a shot and correct the sights for 1/2 of the difference I would expect to see from my center of 10 shot group average. Seems to work for me, but don't know why.
Ric
Attached Files
heh .. when i started shooting 22 rimfire i decided to learn about wind, so i aimed at the bull and observed what the wind flags tried to tell me. got lots of condolences from my shooter buddies for my low scores.
mostly i learned that round nose 40 gr. 224 bullets obey their own secret rules. when my cf br buddies let me shoot their 6 ppc s, the better predictability was impressive.
just some thoughts
ken
Attached Files
Saturday was 40 degrees and windy at 20-25 mph. I took my 6ppc with 80 gr Eagan bullet loaded to about 2300 fps. Alfred E. Newman went with me for his first time to shoot. I'm no top notch shooter, but I informed Al that the wind would blow the bullets around and he should watch the wind flags and wait for a “condition.” He only replied, “What, me worry?"
Al shot, not paying much attention to anything and he said he held on the center of the bullseye every time. His groups: 2.025, 1.315, 1.840 and 2.250, for an agg of 1.857.
I tried to wait for conditions, and shot when I thought it was about the same. I, too, held in one place on the target. My groups: 0.700, 0.600, 0.960 and 1.120, for an agg of 0.845.
This made me wonder about the wind effect and how it shows up in the statistics. It would seem to me that people who shoot in the CBA National Match would not be first time shooters and that they would know a little about reading wind flags. They are aware of the conditions and try their best to compensate for them. Their groups should be smaller that an inexperienced shooter.Here's an attempt to translate the arithmetic into English, a process that I'm notoriously bad at.Wind moves bullet around on the target, we call this wind drift.Shooters attempt to compensate for this wind drift. The compensation methods vary with match rules.Wind drift can be and is estimated very precisely-see the Hornady and/or Federal on-line calculators.Wind drift is not as great as is rumor has it, because wind is not constant over any range AND it does not operate at 90 degrees to the line of flight.CBA NM shooters compensate for the wind pretty well.After compensation, the effect of wind is even less.The BEST shooters do NOT compensate for the wind better than the LESS BEST shooters. The numbers show this. This suggests that compensating for the wind is simple and easily learned-at CBA accuracy levels.If we're going to expend effort/time/$ on shooting more accurately, there are more productive improvement areas than trying to get better at wind doping. Skill and Equipment make more difference.
Attached Files
"Skill and Equipment make more difference."
Yup.
Attached Files
Doping the wind and moving the sights will get you more experience, waiting for the condition (one that does not change much) will get you higher scores. The highest scoring shooters shoot as many rounds in the “condition” as possible and that is their secret to success.
Dave
Attached Files
Doping the wind and moving the sights will get you more experience, waiting for the condition (one that does not change much) will get you higher scores. The highest scoring shooters shoot as many rounds in the “condition” as possible and that is their secret to success.
Dave It seems obvious that the shooters who shoot smaller groups are better wind-dopers than those who shoot larger groups. However, I can find absolutely NO relationship between wind-doping ability and group size. I suspect that wind-doping is relatively easy and quickly learned to a certain level. Once the shooter is over that initial wind-doping hurdle, variations in wind-doping ability are masked by other skills, equipment, and cast bullet inaccuracy.Whatever the cause, the effect, small groups = good wind doping, isn't there. Or I can't find it.
Attached Files
Again, we are looking at apples vs oranges vs pomegranates. The number of factors could be put into an Analysis of Variance program and we would probably see what are the most significant differences in group size. If I gave a great shooter my rifle and loads, and I took his or hers, I believe that they would still have the smaller group. We all shoot in a match in similar conditions. Why do high masters usually get to shoot first? Better conditions. I was firing a pellet rifle today in a pretty stiff breeze. If you want a wind effect, try an eight grain pellet at 650 fps in a 15 mph breeze (which also buffets the shooter) offhand. My group was 50% larger than a non windy day. Elmer Kieth said it best: ” I like big, fast bullets". That combination will always do better in wind than big and slow or light and fast.
Dave
Attached Files
Again, we are looking at apples vs oranges vs pomegranates. The number of factors could be put into an Analysis of Variance program and we would probably see what are the most significant differences in group size. If I gave a great shooter my rifle and loads, and I took his or hers, I believe that they would still have the smaller group. We all shoot in a match in similar conditions. Why do high masters usually get to shoot first? Better conditions. I was firing a pellet rifle today in a pretty stiff breeze. If you want a wind effect, try an eight grain pellet at 650 fps in a 15 mph breeze (which also buffets the shooter) offhand. My group was 50% larger than a non windy day. Elmer Kieth said it best: ” I like big, fast bullets". That combination will always do better in wind than big and slow or light and fast.
DaveDave, I've read it 5 times and still don't know what you're talking about. How about short declarative sentences? Tell us what you think, in terms we can understand.
Attached Files
Sorry. We talk all day about how accurate we can be. However nobody does any proper statistics to see if what they think is the source of accuracy is really what it is. ANOVA would look at the shooter, day, rifle, ammo etc. and tell you what was the significant difference.
Just because one group is smaller or larger than another group, are they really significantly different? Yes the match was won with the smaller group or higher score but were they really different? Anybody can put five shots into one hole at 50 yards at least once. Can they do it twice, five times, 100 times, how about at 100 yards, 200 yards? To me the best shooters will be the best regardless of the conditions or equipment. I would like to see what the group size was on a windy day vs. a calm day across all shooters. My guess is that the better shooters would still have the smaller groups, although maybe not as small as on a calm day. Possibly still rambling but let me know.
Dave
Attached Files
” Possibly still rambling but let me know. “
hi dave;
in ARA rimfire bench shooting, we shot 3 targets of 25 shots each .. i think that is a valid sample, an average 20 shooters at a regional match. because those little round 22 bullets have very small b.c. they blow ( ok, drift ) a lot in the wind.
groups shot in greater windy conditions are larger than groups shot in lesser windy conditions.
at least half the shooters at a ARA match are great trigger pullers ... but only about 20 % are great wind dopers ..those 20% contain the winners.
ken
Attached Files
"groups shot in greater windy conditions are larger than groups shot in lesser windy conditions.” “at least half the shooters at a ARA match are great trigger pullers ... but only about 20 % are great wind dopers ..those 20% contain the winners” Ken: You are not rambling. I agree completely. You can do all the number crunching that you want, but in the real world, the above has been consistently evident in the military CBA matches and during the years that I shot long range BPC rifle gong, silhouette and NRA midrange. I think your percentages may even be pretty close as well. With the group that I shoot the military matches with, there are a number of shooters with like ability and equipment that are perfectly capable of winning all the roses at any match. But, the top dogs are more likely than not, the pilgrims that can read the conditions at any given time and compensate correctly. This is also really evident with the BPCR. Especially at long range ,400-1000 yds because all the errors are greatly magnified. A 550 grn cast bullet at about 1200-1300 FPS really does get pushed around some.
Attached Files
Categories
- All Categories
- General Polls
- Contact Us w/ Forum Issues
- Welcome to The Cast Bullet Association Forum
- General
- Bullet Casting
-
Guns and Shooting
- AR Platform
- TC Contenders & Other Single Shot Handguns
- Shotguns
- Informal Matches & Other Shooting Events
- Gunsmithing Tips
- Gun Cleaning & Maintenance
- Optics
- Benchrest Cast Bullet Shooting
- Military Bench Rest Cast Bullet Shooting
- Silhouette Shooting
- Postal Match Cast Bullet Shooting
- Factory Guns
- Black Powder Cartridge
- Hand Guns
- Lever Guns
- Single Shot Rifles
- Bolt Action Rifles
- Military Surplus Rifles
- Plinkers Hollow
- Muzzleloaders
- Hunting
- Reloading
- Buy, Sell or Trade
- Other Information & Reference
Search
This Weeks High Earners
-
SoreHorseman 2
-
cavelamb 2
-
OU812
2
-
scaglio 2
-
JIsabelle218 2
-
Feral 2
-
ahhbach 2
-
castbulletassoc9 2
-
cylindrically challenged 2
-
Aphyle 2
