No.4 T shooting at 400 yards.

[Strangely Brown]

I found this mark-up online of a standard 303 zero target, with added check dims, and was wondering if there's a mathematical formula for calculating the ranges from the zero point or existing 300 and 600 yards points so as to be able to mark up one for a zero check at 900 yards?
Attachment 110145

Once you have found an elevation that works out to 900x for your rifle and ammunition at Bisley (34 1/2 MoA?) is to then go to the zero range after you have shot at 900x and zero on a 303 SR"b" zero target with your 900x yard elevation.
You could also use a 7.62mm zero card and put a white target patch over half the round bull to make it into a tin hat aiming point.
Once established you have the correct rise in inches for future zeroing sessions.

Also ask in the range office if they still have the old style SR"b" zero cards, these went up to 1000x yards but I suspect they might have all gone now.

Regarding shooting on the NRA TR round bull; the trick here is to use the normal elevation that you would on a tin hat target, (or whatever your elevation calculator says) and simply add half of the target aiming point in MoA to what your elevation should be and aim at the base of the black aiming point.
Doing this at 900x you just add 2 1/2 MoA to your normal elevation of 34 1/2 = 37 MoA.
Ironically I was shooting with the ATSC on Wednesday at 900x with my No.4 SR"b" and did just that.

Information

Warning: This is a relatively older thread This discussion is older than 360 days. Some information contained in it may no longer be current.

[GeeRam]

Regarding shooting on the NRA TR round bull; the trick here is to use the normal elevation that you would on a tin hat target, (or whatever your elevation calculator says) and simply add half of the target aiming point in MoA to what your elevation should be and aim at the base of the black aiming point.
Doing this at 900x you just add 2 1/2 MoA to your normal elevation of 34 1/2 = 37 MoA.
Ironically I was shooting with the ATSC on Wednesday at 900x with my No.4 SR"b" and did just that.

Well I shot 900 yrds at Bisley with the 4(T) this morning, but heat haze at the temps climbed into the high 20's was an issue for the guys shooting 7.62 HB target No.4's with PH5C aperture sights......whereas it wasn't so much an issue for me with the 4(T), and 37 clicks from stop got me just hitting the bank in front of the target, so needed to wind it up about 4-5 more clicks depending on the wind gusts which were from behind and slight across the right...
Anyway the old girl did wonderfully and I bagged a respectable 40.2, which for an old battle rifle at 900 yrds wasn't too shabby I thought.......(and outscored all the 7.62 HB No.4 target rifles guys with their bondage jackets and straps as well, which was amusing )

Probably won't come first the next time though as we've 3 new younger members with just acquired modern black plastic sniper 7.62 thingies with 24x scopes etc., but it was the first time they've shot them and they hadn't quite got them zero'd perfectly or had the wrong rings or some other techy thing, that they were all had programmed into their Iphones from apps from the scope makers