Nicole, as I originally suspected, we're really entering the world of semantics. You visualize the sight alignment and the sight picture as angular error, and parallel error. I visualize them as a vector generated by a short radius(sight alignment), coming off a vector generated by a long radius(arm wobble). I'd call the vector(direction) the bullet travels, the vector sum(cumulative error).
Your description is, of course, easier for a new shooter to visualize.
Paul
Only have 6-7 yards shooting distance in my basement
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You're not firing down a tube. You're firing down a cone with the pointed end beginning at your shoulder.Nicole Hamilton wrote:It's like firing down a tube and moving both ends up/down, left/right, always the same amount. As long as you don't change the angle of the tube, a 1/4" change on the target takes a 1/4" change in your hand.
This why sight alignment (front + rear) is SO much more important than sight picture (sight alignment + bull).
Stan
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Nicole Hamilton
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Albert B
reduced shooting distance and scaled down targets
What I miss in the discussion is the fact that by reducubg the distance you have to compensate for the diameter of the pellet/bullet as well.
Draw a circle (the ring diameter at full range and one at the shorter range. Then draw a line tangent from zero meter/yard tangent to the full range target. The line should touch the reduced target tangent also. This line represents the 'inner' part of the pellet/bullet. Now draw a circle representing the pellet just touching the full size target. Then draw a line from the center of the pellet back to zero meter/yard point. This line represents the centerline of the pellet. You will notice that the distance between the center of the pellet and the edge of the reduced target is less then the distance between center pellet and full size target. Therefore you must not only the target diameter but on top of that also compensate for the diameter of the pellet/bullet.
Reduced target with positive scoring:
Na
RDr = ---- x (RDn + DKn) - DKg
Ra
RDr = reduced ringdiameter RDn = normal ringdiameter
DKg = diameter used pellet/bullet*
Na = normale distance Ra = reduced distance
DKn = normal diameter pellet/bullet
* at reduced target and distance
Participants, start your calculators.....
Albert B
(The Netherlands)
Draw a circle (the ring diameter at full range and one at the shorter range. Then draw a line tangent from zero meter/yard tangent to the full range target. The line should touch the reduced target tangent also. This line represents the 'inner' part of the pellet/bullet. Now draw a circle representing the pellet just touching the full size target. Then draw a line from the center of the pellet back to zero meter/yard point. This line represents the centerline of the pellet. You will notice that the distance between the center of the pellet and the edge of the reduced target is less then the distance between center pellet and full size target. Therefore you must not only the target diameter but on top of that also compensate for the diameter of the pellet/bullet.
Reduced target with positive scoring:
Na
RDr = ---- x (RDn + DKn) - DKg
Ra
RDr = reduced ringdiameter RDn = normal ringdiameter
DKg = diameter used pellet/bullet*
Na = normale distance Ra = reduced distance
DKn = normal diameter pellet/bullet
* at reduced target and distance
Participants, start your calculators.....
Albert B
(The Netherlands)
AlbertB,
I am laughing almost too much to type. Nice dig on the equation and good comic relief. Obviously there isn't some quantum anomaly that resizes pellets to sustain a proportional diameter from zero meters to infinity. It could be the next million dollar widget, though.
The key to using scale targets effectively is to maintain the black to ten ring relationship. If done correctly the scaled target will allow for effective practice. A scaled target, minus quantum pellets, won't necessarily be a good indicator of a match score at 10 meters.
A scaled target reinforces good sight alignment, grip, stance, position, breath control, trigger squeeze, and follow through. Using scaled targets, if not an ideal solution, is much better than not shooting at all. Not shooting is the only unacceptable answer I can think of.
Good shooting,
Phil
I am laughing almost too much to type. Nice dig on the equation and good comic relief. Obviously there isn't some quantum anomaly that resizes pellets to sustain a proportional diameter from zero meters to infinity. It could be the next million dollar widget, though.
The key to using scale targets effectively is to maintain the black to ten ring relationship. If done correctly the scaled target will allow for effective practice. A scaled target, minus quantum pellets, won't necessarily be a good indicator of a match score at 10 meters.
A scaled target reinforces good sight alignment, grip, stance, position, breath control, trigger squeeze, and follow through. Using scaled targets, if not an ideal solution, is much better than not shooting at all. Not shooting is the only unacceptable answer I can think of.
Good shooting,
Phil
The key to using scale target is to maintain the same picture of the black for human eye and make sure that ten or any other shot value at 10 meters will be the same at reduced distance.Dragon 2 wrote: The key to using scale targets effectively is to maintain the black to ten ring relationship.
Albert is right - reduced target rings do depend on bullet/pellet diameter - black does not.
Here we go again!
All reduced targets are proportional to the distance at which they're used. Since all the targets are proportional, if you lined up concentricaly, starting with the closest, a B-11, B-35, B-19, and B-17 target, at their proper distances, and projected a laser beam from the shooter, to the outer edge of the 9ring on the 50M. B-17 target, the beam would intersect the same line on all the targets.
Since all scoring is from the inner edge of the projectile, a bullet that just touches the 9 ring on the B-17 target, would like the laser beam, score the same 9 on all targets. That is why the proportional differences (to the target size) in bullet diameter, for scoring purposes on the different targets, is irrelevant except perhaps, for difficulties with accurate finals-type scoring based upon bullet position within a ring. I don't know if the vernier-type plastic overlays are made for reduced targets.
Paul
All reduced targets are proportional to the distance at which they're used. Since all the targets are proportional, if you lined up concentricaly, starting with the closest, a B-11, B-35, B-19, and B-17 target, at their proper distances, and projected a laser beam from the shooter, to the outer edge of the 9ring on the 50M. B-17 target, the beam would intersect the same line on all the targets.
Since all scoring is from the inner edge of the projectile, a bullet that just touches the 9 ring on the B-17 target, would like the laser beam, score the same 9 on all targets. That is why the proportional differences (to the target size) in bullet diameter, for scoring purposes on the different targets, is irrelevant except perhaps, for difficulties with accurate finals-type scoring based upon bullet position within a ring. I don't know if the vernier-type plastic overlays are made for reduced targets.
Paul
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Nicole Hamilton
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Sorry, Paul, you're wrong, and you don't need to take my word for it. All you need do is compare, e.g., a B-19, used for FP at 50 yards, with a B-35, used for FP at 25 yards. Here are sizes of the rings:
B-19
10 ring ... 1.78 in
9 ring ... 3.58 in
8 ring ... 5.38 in
7 ring ... 7.18 in (edge of the black)
B-35
10 ring ... 0.78 in
9 ring ... 1.68 in
8 ring ... 2.58 in
7 ring ... 3.48 in (edge of the black)
Notice that 2*0.78 = 1.56, which is less, by exactly .22 in, than the 1.78 in diameter of the 10 ring on the B-19. Notice that same difference exists for all the rings.
B-19
10 ring ... 1.78 in
9 ring ... 3.58 in
8 ring ... 5.38 in
7 ring ... 7.18 in (edge of the black)
B-35
10 ring ... 0.78 in
9 ring ... 1.68 in
8 ring ... 2.58 in
7 ring ... 3.48 in (edge of the black)
Notice that 2*0.78 = 1.56, which is less, by exactly .22 in, than the 1.78 in diameter of the 10 ring on the B-19. Notice that same difference exists for all the rings.
Lets assume that pellets have a fixed diameter of, say, 4.5mm. Further assume that an international rules commitee has established a standard scoring device, based on the previously assumed fixed pellet diameter, designated to be 10 meters from a firing line. Scaling a target for less than the estbalished range would effectively increase the relative size of the pellet.
If scores are based on the inner most point of impact then a "relatively" larger pellet will strike closer to the center of the target then it would at 10m for any given shot. Carrying the principle further (and father), the same pellet would strike at a greater distance from the center due to the relatively smaller diameter of the pellet past 10m. This would be true even if the pellets trajectory were laser straight.
For example. A pellet that would just touch the ten ring at ten meters would clearly cut the ten ring at five meters and clearly be a nine at 15 meters. Assuming away ballistic trajectory. The center point of each pellet hole would be proportionally equal distance from the center of three concentrically placed targets at 5, 10 and 15 meters.
If you want to score at reduced ranges you must adjust the diameters of rings to compensate for the "relatively", but not physically larger pellets. That is what Albert was saying, Shin is agreeing with, and I was making light of.
Shin also agreed that keeping the black a proportional size "to the human eye" is necessary. That means that the black on a scaled target, compensating for "relatively" larger pellet size, would extend to more scoring rings than on a 10 m target but would remain proportionally equal and linear with the 10m target.
Scoring rings on a scaled and compensated target will no longer maintain the linear relationship with a 10m target. A purely scaled target will maintain the linear relationship but will not score accurately (relative to the score a 10m target would post).
Scaling your own targets is easy. Scaling and compensating your own targets is harder, but you only have to do it once to make a useful master for unlimited copies.
Good Shooting,
Phil
If scores are based on the inner most point of impact then a "relatively" larger pellet will strike closer to the center of the target then it would at 10m for any given shot. Carrying the principle further (and father), the same pellet would strike at a greater distance from the center due to the relatively smaller diameter of the pellet past 10m. This would be true even if the pellets trajectory were laser straight.
For example. A pellet that would just touch the ten ring at ten meters would clearly cut the ten ring at five meters and clearly be a nine at 15 meters. Assuming away ballistic trajectory. The center point of each pellet hole would be proportionally equal distance from the center of three concentrically placed targets at 5, 10 and 15 meters.
If you want to score at reduced ranges you must adjust the diameters of rings to compensate for the "relatively", but not physically larger pellets. That is what Albert was saying, Shin is agreeing with, and I was making light of.
Shin also agreed that keeping the black a proportional size "to the human eye" is necessary. That means that the black on a scaled target, compensating for "relatively" larger pellet size, would extend to more scoring rings than on a 10 m target but would remain proportionally equal and linear with the 10m target.
Scoring rings on a scaled and compensated target will no longer maintain the linear relationship with a 10m target. A purely scaled target will maintain the linear relationship but will not score accurately (relative to the score a 10m target would post).
Scaling your own targets is easy. Scaling and compensating your own targets is harder, but you only have to do it once to make a useful master for unlimited copies.
Good Shooting,
Phil
Nicole, You're right! I was just going to post that fact after looking up the target dimensions in my rule book, when I saw your post! NONE of the targets are proportionate!
To simplify the math, I checked the english targets and compared the 50ft. to the 50yd, The difference between the ten rings is the worst.:
50yd. ten ring: 1.78".....50ft.: .45"
" one ring: 17.98"...." "...5.85"
a 3-1 ratio should have given the 50ft B-11 rings a size of: 5.93" and 5.99" respectively, instead of .45" and 5.85".
Why did they do this?
A humbled Paul
To simplify the math, I checked the english targets and compared the 50ft. to the 50yd, The difference between the ten rings is the worst.:
50yd. ten ring: 1.78".....50ft.: .45"
" one ring: 17.98"...." "...5.85"
a 3-1 ratio should have given the 50ft B-11 rings a size of: 5.93" and 5.99" respectively, instead of .45" and 5.85".
Why did they do this?
A humbled Paul
Last edited by pgfaini on Tue May 08, 2007 7:51 pm, edited 1 time in total.
Getting back to the relative pellet size argument (made academic with the discovery that the targets aren't proportional), We're not concerned with the relative diameters (in relation to the targets), of the pellets. The inner edge of the pellets would move in the same laser straight line as their centers, and if the targets WERE proportional, would touch the same ring edges on all targets. As I mentioned in my other post, only the type of scoring used in finals would be affected, due to the percentage of the width of the scoring ring the pellet would take up.
Paul
Paul
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Nicole Hamilton
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The way it works is that you have to scale the distance between the center of the black and the center of a shot that would just touch any given ring.
Take the example of scaling the 10-ring from a B-35 to a B-19: The diameter of the 10-ring on the B-35 is 0.78 in, which means the radius from the center of the bull to the center of a shot that would just touch that ring is:
radius to center of shot just touching 10 ring =
0.5 * (diameter of 10-ring) + 0.5 * (diameter of the shot) =
0.5 * (0.78 in) + 0.5 * (.22 in) = 0.5 in
Double that and you get the radius from the center of the bull to the center of a shot that would just touch the 10-ring on a B-35. Subtract the radius of a .22 shot and you get the radius of the 10-ring itself. So the diameter of the 10-ring on a B-35 is:
diameter of 10 ring on B-35 =
(scaling from B-19 to B35) * (2 * (radius to center of shot touching 10 ring) - 0.5 * (diameter of the shot)) =
2 * (2 * 0.5 in - 0.5 * (.22 in)) = 1.78 in
Take the example of scaling the 10-ring from a B-35 to a B-19: The diameter of the 10-ring on the B-35 is 0.78 in, which means the radius from the center of the bull to the center of a shot that would just touch that ring is:
radius to center of shot just touching 10 ring =
0.5 * (diameter of 10-ring) + 0.5 * (diameter of the shot) =
0.5 * (0.78 in) + 0.5 * (.22 in) = 0.5 in
Double that and you get the radius from the center of the bull to the center of a shot that would just touch the 10-ring on a B-35. Subtract the radius of a .22 shot and you get the radius of the 10-ring itself. So the diameter of the 10-ring on a B-35 is:
diameter of 10 ring on B-35 =
(scaling from B-19 to B35) * (2 * (radius to center of shot touching 10 ring) - 0.5 * (diameter of the shot)) =
2 * (2 * 0.5 in - 0.5 * (.22 in)) = 1.78 in
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Nicole Hamilton
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Re: reduced shooting distance and scaled down targets
Btw, Albert's formula was "almost" correct. It wasn't readable mostly only because he omitted the "code" tags around it to prevent reformatting. Here's how I believe he intended it to display:
The one mistake is that the (Na/Ra) factor is inverted. Here's the correct formula:
Code: Select all
Na
RDr = ---- x (RDn + DKn) - DKg
Ra
RDr = reduced ring diameter
RDn = normal ring diameter
DKg = diameter used pellet/bullet*
Na = normal distance
Ra = reduced distance
DKn = normal diameter pellet/bullet
* at reduced target and distance
Code: Select all
Ra
RDr = ---- x (RDn + DKn) - DKg
Na
Of course it works. The two shots are diverging at the same angle all the way from the gun to the original target. The two shots would still span the same relative scoring values on both targets, if they were sized proportionaly,(which we now find they aren't). What does mis-aligning them prove? The diagram has no quantitative value, you could draw it so that the rear target was missed by fifty feet. What would that prove? I thought we were discussing whether there were scoring errors caused by the variations in bullet diameter relative to target size. That was my laser analagy regarding the line of flight of the bullet's inner edge, disproving that as the bullet's relative size(diameter) increased, it would score higher, on proportionaly sized targets.AAlex wrote:It is proving that when the rear sight is not aligned exactly to the target due to wobble, your cone analogy does not work.
This is a popular topic of conversation among Schuetzen shooters, where we commonly shoot calibers from .25 up to .45, and while the larger diameter bullet has an advantage in scoring, the heavier recoil of the larger calibers, more than makes up for it. We also have a special .40 and over match because of this(recoil).
ISSF scoring of center fire matches takes caliber (.32 vs. .38) into account, by calculating a fixed distance(based on .32 cal.) from the center of the shot(s), and I got no benefit with my .38spl. revolver over the .32S&W pistols on the Sius-Ascor targets at the Wolf Creek PTO's.
Paul
That was not part of the discussion until someone had the ingenuity to proclaim the targets scale proportionally, even though it was mentioned indirectly that it wasn't so in the first few posts:I thought we were discussing whether there were scoring errors caused by the variations in bullet diameter relative to target size
This target is scaled incorrectly - at 5m diameter of the inner ten ring should be 0.25mm, and 10 ring should be 3.5mm.
Then the thread switched to the discussion of whether and why the wobble matters more on shorter distances, although the only "rebuttal" was some people bashing the straw man of their own definition of "parallel error".Shooting at lower distances, even with the target black and scoring rings appropriately scaled down, accounting for the projectile diameter, etc.