I'm shooting the HCP rifle match in May Its a team match requiring a bolt gunner and a carbine shooter. Without getting into the carbine I've fully assumed I'd shoot my 6SLR. Its pushing a 115 Dtac at about 3020fps. I'm running it at about 50K PSI; well below its max. For most matches all the target ranges are provided so more velocity for a given bullet really only gives a wind advantage. For this match however the targets are UKD. Shooting the same bullet faster may help when the tgt range is not correct. So I needed to perform some 3rd grade math to determine if running the SLR at 3150 was going to be an advantage over 3020. 130fps difference. Here's what a little ballistic analysis told me.
Assuming my median distance for the longer range targets is 600yds, the target size can be predicted at 2 MOA for these guys, in this part of the country. Therefore my target size is 12" or .6 mrads. This means if I aim center I have .3 mrads below and above my POA to still hit the tgt; .6 total. I ran the numbers on my AB 5700 for .3 above and below my 600yd data and determined what ranges equaled the .3mrad mistake.
If my data for 600 is 2.66 mrad then I can still hit the target, mathematically, at 2.33 and 2.93. A .6mrad difference; the tgt height in mils. So backwards engineering the yardage to those data's, I can determine how much yardage error I can have and still hit the target.
For a 115 Dtac going 3020 2.66 mrads is 559 yd data. 2.96 mrads is 642 data. So I can hit the tgt from a mistaken distance of 559 to 642 yds. Therefore my danger space is 83yds. Anywhere inside that 83yds I should mathematically still hit the tgt.
So going 3150 (assumed node) my 600 yr data is 2.38 mrads. .3 mrads on either side of that is 2.08 and 2.68 yds. My yardage data for those holds are 553 and 645 respectively. Therefore my danger space at that velocity is 92 yards.
So I gain 9 yards of error by pushing the cartridge 130fps faster. IMO not worth developing another load in the higher node for this particular match. I'll run what I got.
In the next post, I'll explain wind danger space in mph and determine the worth of 130fps. It will obviously be less so but we'll do the math anyway for diligence.
Assuming my median distance for the longer range targets is 600yds, the target size can be predicted at 2 MOA for these guys, in this part of the country. Therefore my target size is 12" or .6 mrads. This means if I aim center I have .3 mrads below and above my POA to still hit the tgt; .6 total. I ran the numbers on my AB 5700 for .3 above and below my 600yd data and determined what ranges equaled the .3mrad mistake.
If my data for 600 is 2.66 mrad then I can still hit the target, mathematically, at 2.33 and 2.93. A .6mrad difference; the tgt height in mils. So backwards engineering the yardage to those data's, I can determine how much yardage error I can have and still hit the target.
For a 115 Dtac going 3020 2.66 mrads is 559 yd data. 2.96 mrads is 642 data. So I can hit the tgt from a mistaken distance of 559 to 642 yds. Therefore my danger space is 83yds. Anywhere inside that 83yds I should mathematically still hit the tgt.
So going 3150 (assumed node) my 600 yr data is 2.38 mrads. .3 mrads on either side of that is 2.08 and 2.68 yds. My yardage data for those holds are 553 and 645 respectively. Therefore my danger space at that velocity is 92 yards.
So I gain 9 yards of error by pushing the cartridge 130fps faster. IMO not worth developing another load in the higher node for this particular match. I'll run what I got.
In the next post, I'll explain wind danger space in mph and determine the worth of 130fps. It will obviously be less so but we'll do the math anyway for diligence.
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