If one is reducing a 25m target (used with 22 caliber) to 10m (used with 4.5mm), what is the proper reduction? 4.5mm is proportionately too large for a simple reduction. If you assume the hole made by a 22 bullet measures 5.56mm, then the reduction for 10m becomes 2.224mm. So, doesn't the reduced 10m target have to take this oversize factor into account?
On a related note, I always assumed target manufacturers took into account the effect of using, for example, a 22 at 50m and using that same 22 on a reduced target for shorter distances. But, I'm not sure they actually do.
Ideas anyone?
Stan
Reducing targets correctly?
Moderators: pilkguns, m1963, David Levene, Spencer, Richard H
Forum rules
If you wish to make a donation to this forum's operation , it would be greatly appreciated.
https://www.paypal.com/paypalme/targettalk?yours=true
If you wish to make a donation to this forum's operation , it would be greatly appreciated.
https://www.paypal.com/paypalme/targettalk?yours=true
Reduced target
To maintain uniformity of scores, I think it would require adjusting the scoring rings to suit the projectile diameter, but to maintain uniformity of sight picture, the bull (the black circle) should be reduced in direct proportion. The latter means that the diameter of the black would not likely correspond to the diameter of a scoring ring, ie the edge of the black would lie between rings.
-
David Levene
- Posts: 5617
- Joined: Mon Mar 01, 2004 12:49 pm
- Location: Ruislip, UK
Stan, you are obviously correct in suggesting that you cannot just pro-rata the ring sizes based on the distance. you actually need to do the calculation based on the centre of the hole that would touch the scoring ring.
If we take the 7 ring as an example, you would add a scoring diameter (5.6mm in the case of .22) to the 25m ring diameter (200mm for the 7 ring), pro-rata the total (divide by 2.5 for a reduction to 10m), and then deduct a scoring diameter for the projectile you will be using (4.5mm). This gives us a 7 ring diameter of 77.74mm.
If you wanted to simulate a centre fire match (scoring diameter of 9.65mm) then the 7 ring diameter would be 79.36mm.
There is an additional complication in that the size of the black aiming mark is not dependant on scoring hole diameter and should just be reduced pro-rata to the distance. Once again we have a starting diameter of 200mm at 25m which would give an 80mm black at 10m. Whether this is different enough to the reduced 7 ring diameter to worry about is a matter of personal opinion; I somehow doubt it.
If we take the 7 ring as an example, you would add a scoring diameter (5.6mm in the case of .22) to the 25m ring diameter (200mm for the 7 ring), pro-rata the total (divide by 2.5 for a reduction to 10m), and then deduct a scoring diameter for the projectile you will be using (4.5mm). This gives us a 7 ring diameter of 77.74mm.
If you wanted to simulate a centre fire match (scoring diameter of 9.65mm) then the 7 ring diameter would be 79.36mm.
There is an additional complication in that the size of the black aiming mark is not dependant on scoring hole diameter and should just be reduced pro-rata to the distance. Once again we have a starting diameter of 200mm at 25m which would give an 80mm black at 10m. Whether this is different enough to the reduced 7 ring diameter to worry about is a matter of personal opinion; I somehow doubt it.
The HighNoon postal has a link to an Excel spreadsheet that does this calculation for a reduced target. But this only for ring reduction, which as was stated is affected by projectile diameter.
The thing is most people use the Pellant target program, and it can't make a black bull different than one of the rings. The only way, is a funky workaround, which Ive done, where you give up a ring to use to make the intermediate ring.
For example, a black between the 7 and 8 ring.
You would select the 7 ring, and give it the diameter of the black.
Then from there on you have to use 1 ring lower. IOW the 6 ring is now the 7 ring, and so on.
The ring numbers outside the black are now off because the program does not allow you to enter your own numbers.
Gary
The thing is most people use the Pellant target program, and it can't make a black bull different than one of the rings. The only way, is a funky workaround, which Ive done, where you give up a ring to use to make the intermediate ring.
For example, a black between the 7 and 8 ring.
You would select the 7 ring, and give it the diameter of the black.
Then from there on you have to use 1 ring lower. IOW the 6 ring is now the 7 ring, and so on.
The ring numbers outside the black are now off because the program does not allow you to enter your own numbers.
Gary