winddrift with 54 cal

[sonny]

I went shooting this past sunday trying to get a good hunting load an sight adjustment.cold an windy would be an understatement!.....I shot a decient group with .530rb an 77.5 grains of 3f goex an 020 thou oxyoke wonder patch. My group was 1/4 low an 1" to right with a 15 to 20 mph cross wind left to right.I was afraid to drift my front sight to right to adjust my point of aim because if the constant wind stopped next time i go out, my point of impact would be too far left. I asked a guy there if he thought that the crossing wind would affect the bullet at 50 yds.He said no,too close for anything to affect it.........how much would bullet be affected with my 42" 54 cal barrel an load?.thanks

[SCLoyalist]

According to the Lyman Black Powder Handbook,  you should be getting somewhere around 1600 fps of muzzle velocity with that load.   If the crosswind was 10 to 20 mph, then your roundball would be drifted anywhere between 2.45" (for 10mph crosswind) and 4.89" (for 20mph crosswind) at 50 yards.

[sonny]

geez.........that seem's like a lot!........i thought maybe 1/4 or 1/2" put 2" or better......wow...........sonny

[SCLoyalist]

It seemed like a lot to me, too, but the book's numbers are all consistent for different ball diameters, and muzzle velocities.  

Keep in mind that those numbers are the wind drift for a 10 to 20 mph crosswind.  If the wind were blowing at less than a 90 degree right angle, some of that wind force is downrange, not crossrange.   For example, a 20 mph wind blowing into your face but  off to the side 45 degrees would resolve into about a 14 mph crosswind and a 14mph headwind.

If you don't have a wind gauge or wind measuring instrument, wind estimation is more an art than a science.  It may be the wind wasn't blowing exactly from the side, or maybe the wind velocity was lower than it felt.  Here's a link to a Weather Service site for visual cues on estimating wind:
http://www.wrh.noaa.gov/pqr/info/wind.php

Going back to your original numbers, a left to right wind, and hitting 1" right of point of aim at 50 yards, either your rifle would shoot a couple of inches to the left on a still day, or your estimation of crosswind speed was too high.  You were right, I think, not to drift your front sight to compensate for one-time wind conditions.

SCL

[northmn]

Roundballs are very affected by the wind.  When I shot in the Western Mn plains there was one range that faced North and always had a gale for a cross wind.  To get hits at 100 yards with my 58 I would have to aim at the edge of a 24 inch paper bullseye at times.  I used to often put out my 100 yard targets first at matches to shoot in the morning before the wind came up.  It takes a while to be satisfied with sighting in the fixed sights on a muzzle loader, and I would wait until a more reeasonable opportunity presented itself before final filing and drifitng.  I used to be amused at the folks shooting the factory ML's like the TC's, Lymans and CVA's with adjustable sights. They were always chasing their sights around adjusting them on various days.  Those of us with fixed sights did not have that problem.  Sun on shiny silver front sights can also give you fits.  Thats why I like a brass bead.

DP

[Don Getz]

Sonny......you are concerned about 1/4" vertical and 1" horizontal movement?  I'm willing to bet that you get greater than
that spread within your group............Don

[Daryl]

Yeah - I thought the 'spread' was a bit tight, too, to be of any concern.  With a .50, that measurement was 1/2 ball high, and 1 1/2 balls right at the cetnre of one ball or 1 ball high and 2 balls right of the outsdie on one ball.  Sonny- how many shots were in that group & what size was the group on centres. 

[sonny]

nope Don..........with my getz barrel 42" 54 cal it shoots them into a nice quarter group........I did not try to drift my new sight over to get dead on cause when the wind die's down it might be too far left........do you think my results are unusual???........sonny

[sonny]

daryl............with new sights an clean barrel it shot the first ball about 3" right of center an 1/4" low.....I drifted sights  over an shot the next 4 into a quarter size group that made me put it away for fear that an evil demon would push the shot far far away an ruin my holiday!!!!! ha ha ha .....too @!*% cold an way too windy to keep on,actually!......I just wanted to get gun an new sight somplace in middle to hunt with this season.I shoot near a lake an you never saw such constant wind on a rifle range!never.....sonny

[Stonewall Creek]

i have shot my .54 cal bench gun alot with a 165 gr- 180gr of powder wind is something you have to learn shooting with wind flags 50yd we shoot a small 6 bull and a wind flag blowing 1/4 up the whole distance can blow you over a 1in , if they are straight out it can move you 2in and more also angle of the wind can move you even more so you did the right thing not moving your sight i have a rule of thumb on hunting guns i set them in no wind and low light because these conditions can drive you crazy.

[Daryl]

At a muzzle velocity of 1,600 to 1,700fps and a mere 10mph crosswind, the .54 ball will drift almost exactly 2". Note that a wind from the left will usually make the shot go low, while a wind from the right will raise the ball somewhat - or is that basakwards, just as tail winds will rise the ball's impact and wind from the front will make the ball drop even more, but wind from the front right quarter will maintain level but give left drift - I think.

[Walks with Fire]

Wind can be laminated as well or blowing in one direction on the top and the other way on the bottom if shooting up/down hill. It can swirl or blow in both directions on the horizonal plane as well. Push it one way then back the other. Push it down into a headwind and raise it on a tail wind. Wind can really test a sight in session! Wait for a calm day and get it dialed in. Stick with your load and learn to read that wind after that. The more you shoot in the wind the better you will get at reading it. A 10 mile per hour steady crosswind will drift a .54 ball with that load about 9" @ 100 yards believe it or not; it's up to you. A .54 ball has a bc of .075.

A ten mile crosswind is not alot either and people new to the ball game will keep chasing their tail at the longer ranges and start second guessing their load or adjusting their sights when one shot goes left and then the next goes a little low and right. It's the wind that keeps changing. Test it again on a calm day and it will still be zeroed.

[Dphariss]

I shot a gallon milk jug full of water at 93 yards the other day in a 20MPH or so wind close enough to 90 degree to give full effect. Held a full milk jug or a little more up wind and got a good hit first shot. Pretty good guess. Wind scattered and mixed the busted jugs so I could not tell which one I shot, if we even found it in the sagebrush. Yeah it was blowing good by the time we left.
Shooting 60 yard rest matches in the wind at Cody has proved useful it seems.
I have seen drifts in feet at "normal" hunting ranges out here where the wind blows a lot.

Dan

[Bean]

Interesting thread.  I hadn't looked up the BC yet for round balls.  A .075 would result in about a 6 multiplier to the average modern ammunition for drift.

[Walks with Fire]

Hornady ammo has an online free ballistics calculator to get an idea of what your loads will do. Use the hangun selection for short range. Might give you an idea what to expect. I know when I first started shooting targets at the range with a 50 I thought that there was no way the wind made that much difference; I was one of those guy's chasing the tail at one point. I check my zero on calm days and play the wind now; it opens up a whole new dimention to ball shooting.

[Daryl]

About 4 years ago, I downloaded a ballistics program - free, called Point Blank.  Cross referencing it with the Sierra program showed almost identical figures.  Since Sierra's program is about spot-on, so is the free Point Blank - for bullet drops, etc.  you need to know the bullet's BC and velocity, as with any program.  I don't know if it's still available, but a google search should provide that answer.