AmericanLongRifles Forums
General discussion => Black Powder Shooting => Topic started by: Daryl on July 30, 2008, 09:10:44 PM
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I set the parameters in the point blank computer program for: The load used was my .40 cal accuracy load of 65gr. 3F with a .400" ball.
sight height== 3/4" above bore axis
elevation==== 2,000ASL
zero======= 50 yards
BC======== .070
ball weight===96gr.
velocity===== 2,150fps
zero======= 50 yards
Results:
: 25 yards was .07" low
: 75 yards was .70" low
: 100 yards was 2.45" low
Wind deflection 10mph at 90 degrees - 50 yards-- 1.68"
----------------------------------------------- - 100 yards- 7.49"
: At an initial velocity of 1,800fps same other parameters
: 25 yards was .06" low
: 75 yards was 1.2" low
: 100 yards was 3.87" low
Wind deflection 10 mph 90 degrees - 50 yards 2.12"
---------------------------------------------- 100 yards 9.02"
: Wind deflection difference at 50 yards is only .44" difference, but that makes a difference in a chunk or bench match.
: Wind deflection difference at 100 yards begins to have more meaning at 1.53" in regards scoring on offhand targets and the heavier loads must be considered.
; In larger bores, there is almost the same drift as BC of the balls raises little with bore size increase as far as most match-type rifles are "oncerned, ie: .36 through .54.
: I do wish I hadn't lent out my Lyman BP handbook to get correct BC's to test one against the other.
; Would someone mail me the BC's for .36 through .62's??? Pleeease? ;D
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It appears that you failed to allow for Coriollis Effect and Martian tides. :P
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Wind deflection is so much of a guessing game with the ol r ball :o
Guess at wind speed, guess at wind angles which vary right to left etc. The bench boys use the wind flags and run 30 minute relays (or longer) and they wait and wait and wait somemore til those flags drop or at least all lean the same way. Being a thick head I try to outguess all those variables and usually lose the guessing game; but at least I keep the barrel warm! ::)
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Pretty much me, too, Roger - flags are necessary for precision, of course, but I lack the patience to wait. I usually sned one down onto the sighter target, then fire away just as the wind changes back - caught that way many times.
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Daryl: from Lyman Black Powder Handbook, first edition: .319 is .045. .350 is .049. .375 is .053. .440 is .062. .445 is .063. .451 is .064. .495 is .070. .535 is .075. .562 is .079. .735 (in exterior ballistics table, but shown as .715 in loading data) is .104.
From the second edition: .310 is .043. .350 is .049. .440 is .062. .490 is .068. .495 is .070. .535 is .075. .570 is .080. .715 is .097.
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It appears that you failed to allow for Coriollis Effect and Martian tides. :P
One of the funiest outdoor stories I ever read was by the late Ed Zern, explaining why he missed a game bird on the wing because he didn't account properly for the Coriollis "force". Of course it would be opposite in the southern hemisphere...reminds me of his recipe for elephant, it starts: "take one elephant, dice it..."
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Thanks Herb- Dan P also sent me the numbers.
: The ballistics I noted in my first post, are then the downrange ballistics you would get from a .495" ball in a .50, of course, not a .40. the .40 will have very slightly more drop, wind drift, etc, but not as much more. The true BC of a .395" or .400" ball will be something on the order of .057 ish.
: Well, I should have held my tongue - guessing is such folly - depending on what you'd call 'much more' etc .
: 1,800fps - .400 ball - 25 yds. + .09".......50 yds. "0".......100yds. - 4.42" Wind @ 25yds. .64"..... 50 yds. 2.66".......100 yds. 11.15"
: 2,150fps - .400 ball - 25 yds. - .05"........50 yds. "0".......100yds. -2.90" Wind @ 25yds. .46"..... 50 yds. 2.12".......100 yds. 09.59"
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JEEZ!!!!!!!!!!! Just go shoot the durn thing, it's a lot more fun!!!!!!!
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I remember reading Jack O'Connor who explained why his wife often out shot him. She did not think avout things like wind drift and drop, did not over compensate and therefore hit the target. Also no ego. If she hit it was "can't that little lady shoot!" And if she missed it was "who would expect that little lady to make a shot that difficult" .
The wind drift is of real interest as I ahve seen round ball, even out of big bore go all over the place in a wind. Matthew state that for shooting 1000 yard targets ML differences is of little consequence (BP cartridge) its the wind you cannot allow for consistantly. Made sense to me. A drift of 7.45" at 10 mph or one of 9.02" is also of little consequence as that has to be allowed for or you are off target. Gusty winds eat you for lunch. I remember one range where I shot a 58 and had to hold about 18 inches at 100 yards to get into the bull. Forget about centering the thing.
DP
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Additionally, it depends where the wind is. A wind up close to the shooter will have a more pronounced effect on POI then the same magnitude of wind further down range.
Sometimes I shoots and thinks and sometimes I just shoots. ;D
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I remember reading Jack O'Connor who explained why his wife often out shot him. She did not think avout things like wind drift and drop, did not over compensate and therefore hit the target. Also no ego. If she hit it was "can't that little lady shoot!" And if she missed it was "who would expect that little lady to make a shot that difficult" .
The wind drift is of real interest as I ahve seen round ball, even out of big bore go all over the place in a wind. Matthew state that for shooting 1000 yard targets ML differences is of little consequence (BP cartridge) its the wind you cannot allow for consistantly. Made sense to me. A drift of 7.45" at 10 mph or one of 9.02" is also of little consequence as that has to be allowed for or you are off target. Gusty winds eat you for lunch. I remember one range where I shot a 58 and had to hold about 18 inches at 100 yards to get into the bull. Forget about centering the thing.
DP
I found that at 200 yards any breeze caused the RB to do strange things. This a .535". Like a 22 at longer ranges they will sometimes go up/down rather than drift downwind or even UP wind slightly. Heavy (2.5-3.5 calibers long) bullets are a lot more predicable.
Dan
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I shoot gophers at long rang with .17 cal. rifles - some are rimfires. I've seen the wind in action and put out flags if I remember them. I know for a fact it is easier to dope out 7" of wind rather than 9". Those 2 inches don't sound like much but do make a difference in the number of :o, especially on something only an inch to 1 1/2" wide. Yes, we use scopes, but they don't adjust for wind by themselves.
Locally at our range, the wind changes direction constantly. It's a real badger to figure out.
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I saw a tape on military sniper training. they would look at riffles on a nearby pond for instance. If the riffles were white capped they were trained not to shoot as a hit would be too hard to calculate and the risk taken for nothing. This is with modern high power rifles. A round ball would be even tougher. I should have spell checked my earlier comments, but basically muzzle velocity is something sights can consistently compensate for, wind, especially gusty wind you cannot. At a few target matches one can set up a sighter target. With flags one can get into target. Out in the field where one does not have a consistant angle, etch longer range hits can be almost hopeless with round ball.
DP