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FX "50 yard" 1/2" accuracy claim.

I was taught to measure the widest outside edges of a group and subtract one projectile width to get true C.T.C accuracy results. A dime will cover three .22's in a straight line touching each other (not tears) and the C.T.C group will be .44" Am I wrong?

To get a somewhat accurate result using your method, "one projectile width" would need to be defined as 'the measured apparent width of one projectile hole in the target medium'. This would need to be measured. Depending upon the pellet used, pointed, round head, flat head etc., and the target medium, the hole may be as small as .17"or even less for a nominally .22 pellet

Pellet holes are never the full diameter of a shot pellet. So, measuring across to outside edges of widest shots becomes a lesser measurement than reality - from which a subtraction of an actual pellet width will result in a lesser measurement for the group than reality.

Depending upon the nature of the group and spread of its holes, a fair alternative is to measure, using the widest holes, from the apparent outside edge of the one to the apparent inside edge of the other which takes account of the actual size of the holes.

Another, in the field, is to simply measure from the apparent centre of one widest hole to the apparent centre of the other widest hole in the group. This relies on the fact that our eyes very accurately can pick the centre of a circle/hole. 

Beyond that, if the instructions are well followed, programmes such as the "On Target" app are excellent for the purpose.

Kind regards, Harry.


 
I have shot sub 1/2in groups with 3 FX rifles also at 60 yards. Bobcat,Impact and boss. Definitely accurate rifles.
1551314878_10684491815c772fbe9e22a6.25703542_12321.jpg
This is my best group to date 5 shots 58 yards Fx Impact .25 JSB heavy's
 
I was taught to measure the widest outside edges of a group and subtract one projectile width to get true C.T.C accuracy results. A dime will cover three .22's in a straight line touching each other (not tears) and the C.T.C group will be .44" Am I wrong?

To get a somewhat accurate result using your method, "one projectile width" would need to be defined as 'the measured apparent width of one projectile hole in the target medium'. This would need to be measured. Depending upon the pellet used, pointed, round head, flat head etc., and the target medium, the hole may be as small as .17"or even less for a nominally .22 pellet

Pellet holes are never the full diameter of a shot pellet. So, measuring across to outside edges of widest shots becomes a lesser measurement than reality - from which a subtraction of an actual pellet width will result in a lesser measurement for the group than reality.

Depending upon the nature of the group and spread of its holes, a fair alternative is to measure, using the widest holes, from the apparent outside edge of the one to the apparent inside edge of the other which takes account of the actual size of the holes.

Another, in the field, is to simply measure from the apparent centre of one widest hole to the apparent centre of the other widest hole in the group. This relies on the fact that our eyes very accurately can pick the centre of a circle/hole. 

Beyond that, if the instructions are well followed, programmes such as the "On Target" app are excellent for the purpose.

Kind regards, Harry.


Exactly Harry!

But most people do it the other way (subtract the caliber) and usually report their best targets not an average of 5 groups of 5 shots each (as an example).