GTA
Target Shooting Matches, Discussion & Events => Target Shooting Discussion Gate => Topic started by: Random Plinker on August 13, 2011, 12:02:49 AM
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This post attaches files (must be logged in as a member to see them) named “AirPistol5M...pdf” that contain air pistol targets reduced in size to score essentially the same when shot from a firing line 5 meters from the target face as the regulation ISSF Olympic 10 meter air pistol target when shot from a firing line 10 meters from the target face. Files with 55 in the file name contain targets additionally scaled to score essentially the same with 22 caliber (i.e., 5.5 mm) pellets at 5 meters as the ISSF air pistol target shot with 177 caliber (i.e., 4.5 mm) pellets at 10 meters. "SmallTrap" files are designed for the 5 1/2" square Gamo cone pellet trap, or small traps holding same size targets. Don't forget to "flip" the "smalltrap" half sheets around before shooting the top two bulls, or you'll redecorate your drywall!
These pdf files print to both 8.5x11 "Letter" or A4 sized paper (except "SmallTrap" versions are meant for just 8.5x11), provided the targets are printed centered and print options to scale to the printable area are unchecked or not selected.
If you are looking for ISSF compliant 177 caliber 10 meter air pistol targets, or same adjusted for 22 caliber, go here:
http://www.gatewaytoairguns.org/GTA/index.php/topic,26854.msg244323.html#msg244323 (http://www.gatewaytoairguns.org/GTA/index.php/topic,26854.msg244323.html#msg244323)
The diameters of the target rings, designated DR, are scaled by changing the Scoring Distance (SD) associated with each scoring ring in proportion with the change in Length (L) from the firing position to the target face. SD is the length of the longest line between the centers of two pellet holes with diameter DP that both still score a target ring value; however the calculation of SD depends on how a target ring is scored.
For purposes of this post, most target rings are "outside scoring". As stated in ISSF rules, except for the 10 meter air rifle Inner 10 ring (i.e., a score of X), pellet holes are scored according to the highest value of the target scoring zone or ring that is touched by the pellet hole. If any part of an outside scoring ring (demarcation line between the scoring zones) is touched by the pellet, the shot is scored the higher value of the two scoring zones. Targets scored this way can be labeled "inside scoring," but this is in reference to use of an inward scoring gauge, i.e. the inward edge of the gauge touches or breaks the outside line of the target ring. Very confusing, but there you have it.
An inside scoring target ring can also be defined. Again, the terminology in this post refers to how the ring is scored, not the type of scoring gauge used on the target. With inside scoring, the shot is scored according to the outside edge of the highest value scoring ring the pellet hole remains within.
Finally, a removal scoring target ring can be defined. With removal scoring, the shot is scored according to the highest value scoring ring completely removed by the pellet hole. For example, the Inner 10 ring on the ISSF 10 meter air rifle target is a removal scoring ring, which happens to have the same diameter as the outside scoring 10 ring on this target.
SD for a reference target ring (i.e., SDr) is calculated from the pellet and ring diameters of the reference target (i.e., DPr and DRr) using the SD equation applicable to the type of scoring ring (outside scoring ring SD=DR+DP; inside scoring ring SD=DR-DP; and removal scoring ring SD=DP-DR). SDr for an outside scoring reference target ring is:
SDr = DRr+DPr
Scaled SD for the new target (i.e., SDn) is always equal to SDr multiplied by the ratio of the new length (i.e., Ln) to the reference target length (i.e., Lr) from the target face to the firing position.
SDn = Ln/Lr * SDr
Finally, the scaled new target ring diameter (i.e., DRn) is calculated from the new pellet diameter (i.e., DPn) and the SD equation applicable to the type of scoring ring selected for the new target ring. If we decide to make the new scaled target ring outside scoring, its diameter is:
DRn = SDn - DPn
But, if we decide to make the new scaled target ring removal scoring, its diameter is:
DRn = DPn - SDn
Decisions, decisions. In an ideal world, all target rings would be outside scoring. Unfortunately, when the new Length (Ln) is shorter than the reference Length (Lr) from the firing position to the target face, new outside scoring target ring diameter(s) scaled from the smallest reference target ring diameter(s) may become smaller than twice the target ring line thickness, or worse, negative. The border line thickness of a circle object can be reduced to zero in drawing software, but negative is definitely not good. A removal scoring target ring may be the next best option in this case, because an outside scoring ring and a removal scoring ring are essentially equal in difficulty to score with an undersized pellet hole such as that made by a domed or pointed pellet, whereas converting an outside scoring ring on a reference target to an inside scoring ring on a new scaled target may change the scoring characteristics of the reference target for other than perfect wad cutter pellet holes, or judicious use of a scoring gauge. However, removal scoring rings become rather problematic if they scale larger than a pellet hole diameter on the new scaled target! Finally, two scoring rings too close in diameter can become indistinguishable on a printed target, so inside scoring rings have their place too on scaled targets. Were it not for the fact that outside scoring is "normal", inside scoring rings have the advantage of scaling to any distance without disappearing - shooting cannot get better than a pellet sized hole in a pellet sized target ring no matter the distance!
At least the black bullseye diameter on a target is for optical sighting only. The diameter of the black bull can be scaled by the ratio of Ln to Lr, without regard for scoring distance, scoring ring type or pellet diameter to provide the same visual picture. Most of the attached scaled targets use this simple approach, which results in the black bull at 5 meters being slightly larger than the 7 scoring ring. Unfortunately, making the black bull appear optically the same ignores pellet trajectory. Sights adjusted for a 6 o'clock hold on the black bull of this scaled target at 5 meters will tend to place pellets a little high on the real target at 10 meters. For a pistol with 11/16" sight height shooting 0.011 ballistic coefficient pellets at 500 fps muzzle velocity, with the muzzle extended about 0.5M over the firing line, a black bull near the diameter of the 8 ring on the scaled 5 meter target would be needed for a 6 o'clock hold to put the pellet in the center of both the scaled target at 5 meters and the reference 10 meter air pistol target. Trying to account for different combinations of pellet velocity, ballistic coefficient, sight height, sight picture, arm length, etc. would get ridiculous in a hurry. The important point is that without a small sight, sight picture, or pellet trajectory based black bull diameter adjustment, a good shot may notice shooting a couple pellet diameters or so low/high at 5 meters vs 10 meters (or vice-versa). The rest of us may never notice.
Most drawing software centers a line on the edge of drawing objects, such as circles. As stated in ISSF rules, however, target ring diameters are measured from outside edge to outside edge of the target ring lines. Therefore, the circle diameter specified in such drawing software must be the desired scoring ring diameter minus the scoring ring line thickness, otherwise the target scoring ring diameters will be too large by the scoring ring line thickness specified for the border of the drawn circle objects.
If caliber adjustment and properly accounting for line thickness seem like splitting hairs, consider that the 177 caliber 10 meter air pistol 10 ring scaled to 5 meters is 3.5mm in diameter for 177 caliber, but only 2.5mm in diameter for 22 caliber. A 22 shooter using 177 caliber scaled 5 meter targets gains an unfair 40% advantage on 10 scores if a target adjusted for 22 caliber pellet holes is not used. Ignore line thickness of 0.2mm on the 2.5 mm ring and it becomes 8% easier than it should be to score a 10. Use non standard extra thick target ring lines without accounting for how the drawing software works, and the advantage grows again.
The concept of new and reference shooting distance is more straightforward for rifle than pistol. With a rifle, the barrel and rifle stock lie on an imaginary line pointed at the target that originates from the shooter's shoulder, located approximately at the firing line. If a pistol shooter makes no shooting errors at the hand, the pistol barrel also lies on the same imaginary line originating from the shooter's shoulder. However if a pistol shooter makes a shooting error at the hand, the imaginary line from the barrel to the target now originates approximately 0.5 meters closer to the target face at the shooter's hand stretched over the firing line.
If one assumes all pistol shooting errors occur at the hand (clearly not always the case), this can be accounted for by setting both Ln and Lr equal to approximately 0.5 meters less than the new and reference firing line distance when calculating the scaled pistol target ring diameter. Alternately, one can simply stand 0.25 meters (10 inches) behind the 5 meter firing line to be assured one is not gaining a scoring advantage over the reference 10 meter pistol target due to an assumption that all pistol shooting errors are at the hand. This is the case because (5.25 meters - 0.5 meters)/(10 meters - 0.5 meters) = 0.50, which is the same ratio as Ln/Lr for scaling from 10 meters to 5 meters if this potential pistol specific scaling affect is ignored.
The attached targets scaled for 5 meters ignore the above potential pistol specific scaling issue. So if you believe it, stand somewhere between 0 and 0.25 meters (10 inches) behind the 5 meter firing line, depending on what percentage of your shooting errors you believe originate at your hand. I decided this approach was better than posting targets that account for this postulated affect, because the ring sizes of such targets would disagree with those of other pistol targets scaled using the same method as used for rifle targets.
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Edits:
Added description of scaling issue specific to pistol, and how to account for it if one is so inclined.
Redefined X on 5.5mm caliber scaled 5 meter versions to require complete removal of the X ring to score X; realized removal scoring would be better than inside scoring after thinking on this some more.
Relocated 10 meter targets to their own post.
Added some more refined thoughts on black bull size, and some experimental small bull targets
Added borders to center two bulls on the 12 bull targets to mark them for sight-in/practice only
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If you can push out to 6 meters that would be better. The closer to 10m you can get the better. Even corrected for pellet size, from what I've read, you still don't get a good match to your scores shooting at 10 meters. This is probably for other reasons, but it is better than nothing. So a reduced range target is best used for practice where you do not have 10 meters, and any practice is better than no practice.
BTW I have the spreadsheet to calculate a reduced range target, with pellet diameter compensation. It was from the now defunct "high noon" postal matches. While their equation is slightly different, the resulting numbers are the same.
One hint about the targets, if you use the sub-6 hold, the multi-bull target does not work well. The target below the target you are aiming at will get into the sight picture. I need more vertical space between targets to use the sub-6 hold.
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Appreciate the advice on pushing out to 6 meters. Something to shoot for as I get better. It would also bring the X back on the 22 targets, instead of having to eyeball how centered the hit is by comparing to the sample picture I put on the targets. Thanks for confirming the formula too.
For now, I feel like I'm pushing my luck past 5 meters (missing my small trap) due to jerking the trigger once and a while, with the multiple bull targets anyway. Fear drove me to squeeze the multiple bull targets together toward the center too! I'll look out for neighboring bulls creating sight picture interference with a 6 o'clock hold next time I use one. Might need to make some adjustments if the white ring space is not enough between them.
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I could only run the comp for 4.5mm as the high noon formula is only for .177 since they only shoot comp matches with .177.
The formula they used is:
reduced-distance / standard-distance * standard-ring-size * (reduced-distance / standard-distance - 1)
so for 5 meters and the 5 ring it would be
5 / 10 * 91.5 ( 5 / 10 - 1 )
I think I figured out why they might have set 6m as a min distance. At 5m the spreadsheet specs the 10 ring at 3.5mm, which is smaller than the diameter of a pellet. At 6m the 10 ring is 5.1mm.
I know what you mean about missing the target, I shot the outside bull on a multibull target at 5m and I hit the trap. A fragment of the pellet bounced back and hit me in the face only a couple inches from my eye. I was glad that I wear shooting glasses. Now I make sure that I have plenty of space around the bull to catch the "flyers." And no more shooting next to the edge of the trap.
Shoot the target and evaluate what your eyes sees. If you shoot with a 6 oclock sight picture, it won't be as bad as shooting with a sub-6 sight picture like I do. I find too many bulls in my vision distracts me from the bull I'm trying to shoot at. So I cut up my multi bull targets and shoot at only one bull at a time.
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reviving the dead (as i just found this post)...thank you RP for the 5M targets! ;D
basement wall suffered as i made the mistake of sighting in my AG's at 10M :o
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reviving the dead (as i just found this post)...thank you RP for the 5M targets! ;D
basement wall suffered as i made the mistake of sighting in my AG's at 10M :o
That's what spackle and wood putty was made for!!!
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Random Plinker,
It would be cool if we could use these targets in the competitions as shooting in my garage at 10 meters means I have to shoot corner to corner. It is a bit crowded, but still doable at 10 meters, but 5 meters would be much easier. Thoughts?
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I would guess the 5M targets might be twice as sensitive to small differences resulting from variation in shooter arm length, minor firing line measurement variations, etc. It may also be a little easier to ignore focusing on the front sight at 5M than 10M since the target and sights are closer to each other, but mostly if I forget that at any distance, I'm right there with ginoe fixing holes in my wall! The scoring distance concept otherwise seems sound. I do tend to shoot mostly in the same wide range of scores on both the scaled 5M and "real" 10M target.
That said, the few scaled matches I'm aware of were run separate from the regulation 10 meter matches. My thoughts are that such a match should probably be its own match if it were done. ac12 and others may have some past experience in this area one way or another. Mine is quite frankly rather limited. Like you, I thought the concept was cool and ran with it.
Another thought might be to swap out the target used for the current open 5 yard/meter pistol match from the GamoX5 target to any of the 5 bull caliber appropriate scaled 5M targets I posted. The targets would be less forgiving than the Gamo, so scores would drop and spread out more, but it might also increase interest in this match by making it more of a natural companion to the 10 Meter Target Pistol match. The downside though would be the risk in changing this match at all, as it is currently popular as is.
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Stu
If you can put out at least to 6 meters, that would be better.
Things get complicated when you compensate for pellet size and you go inside 6 meters.
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I don't understand the advantage of keeping the 10 ring larger than a pellet diameter, since pellet holes are scored according to the highest value of the target ring that is touched by the pellet hole (i.e., the outside of the ring, not the inside).
Things do get complicated though when the scaled ring size for an outside scoring ring goes negative, i.e., it is not possible to create a ring small enough to match the scaled scoring distance if scoring is by the pellet hole touching the outside of the ring. This happens to the "X" ring for the scaled 5M 22 caliber targets. The complication is that the only way to handle this is to define an inside scoring ring diameter for this case. Since scoring is to the inside of the ring instead of the outside, pellet diameter is added instead of subtracted from the scaled scoring distance to calculate the diameter of the "inside" scoring ring. The "inside scoring" X ring in the scaled 5M 22 caliber target is then 10.25 mm. Fortunately, the diameter of the outer edge of the normal outside scoring 9 ring on the 5M 22 target is 10.50 mm, and the line thickness is 0.2 mm; therefore the diameter to the center of the 9 ring line is 10.30 mm. Technically, a tolerance of zero is allowed by ISSF rules for the diameter of the X ring. Practically, the diameter error in the X scoring guidance on this target of 0.05mm, or one quarter of the line thickness, is negligible. I figured "Inside Middle of 9 Ring Line" would be easier to visually score than "Inside 3/8 of 9 Ring Line Thickness" for scoring an "X" on the 5M 22 target.
The 5M 22 targets have one more feature. I placed the black bull on the 10M 22 targets at the 7 ring (just like on the standard target), but on the 10M 22 target this ring is 1 mm less in diameter than that on the standard target for 177 pellets to adjust for the larger holes made by 22 pellets. So I scaled the non-scoring black bull (non-scoring because it is for sighting purposes only, so no pellet diameter accounting is made for scaling this ring) for the 5M 22 targets starting from a diameter reduced by 1 mm on the 10M 22 target. This feature has no impact on scoring, and keeps the 10M and 5M 22 target bulls optically consistent.
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...keeps the 10M and 5M 22 target bulls optically consistent...
the reason why i like these scaled targets, at 5M they appear to be at 10M
if i could find scaled targets to simulate 300yards (at say 10M), I could practice using my M417 (prone, seated, standing positions) i learned in the civilians marksman class i took with the M16
-edit- if i calculate correctly, target is about the size of a dime
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Optically scaling the target is the easy part.
6 meter actual vs 10 meter regulation, is regulation ring diameter * 6/10
And this is also how you determine the diameter of the BLACK bull.
But when you adjust for pellet size, the scoring ring diameters will change, but the black bull must remain the same size.
Similarly reducing a 300yd target to shoot at 10m.
300yd = 274meters
10m actual / 274 meters regulation = 0.0365 ring adjustment factor
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The correct adjustment factor to reduce scoring rings on a 300 yard (274M) target to 10M is not simply 10M/274M=0.0365.
One must also account for the unique diameter of each scoring ring and the diameter of the projectile (0.223 I presume for an M16), in addition to the ratio of the old and new target distance.
The reason for this is that you cannot shrink the size of the hole the bullet makes, so you need to shrink the rings more than by just the distance ratio to keep the scores the same for the same shooting ability. The smaller the ring (i.e., the closer the size of the ring is to the size of the bullet hole that you cannot also shrink), the smaller the adjustment factor needs to be to account for not being able to shrink the bullet.
If this still doesn't make sense, try out the formula in my initial post in a spreadsheet ring by ring. That may help.
If you divide out the scoring ring diameters listed on my 5M and 10M air pistol targets, you'll see the adjustment factor is not simply 5M/10M, or 0.5. The factor is, and needs to be, different for every ring. For example the ratios for the 177 caliber target range from 0.050 and 0.304 for the X and 10 ring, to 0.486 for the 1 ring. So you see, the 5M target will not and should not appear exactly 1/2 the size of the 10M target. Granted the 1 ring at a ratio of 0.486 is pretty close, but not the 10 ring at a ratio of 0.304.
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@RP
Sorry, I realized I wasn't being very clear.
There are 2 things to consider when making a reduced range target.
#1 The scoring rings, which should be adjusted for both distance and projectile size as you indicate.
#2 The black bull that you aim at, that is scaled down by only by distance, since you are only visually aiming at it. This results in the size of the black bull not matching the scoring rings, but being in between scoring rings. Just as you made them in your reduced range target.
You are correct, I ran the spreadsheet for the 10m reduced range targets.
The AP target used an inner ring scoring, and for distances less than 5m they were still good.
It was the AR target that used an outside scoring ring for just the reason you mentioned. If you used inner ring scoring, at less than 9 meters, the calculated diameter of the 10 ring went negative. But with outer ring scoring you could get under 5m.
So I don't really know why the High Noon postal selected 6m as the min distance for reduced range targets.
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Here is a link to a scaled down 10 meter air pistol targets from 9 to 5 meters . You will notice a off set in the black , this is so you don't have to adjust your sights when shooting at closer distances if your sight is set for 10 meter . It explains this on the first page . you just pick the off set that puts your pellet in the center according to your sight setup . add http:// w w w to this link when you copy and paste . .luftvapen.info/Downloads/maltavlor/air_pistol_target_resize.pdf