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Old April 8, 2013, 03:26 PM   #12
Join Date: March 4, 2005
Location: Ohio
Posts: 13,654

Your welcome to whatever help we can offer.

Check which 168 grain bullet they calibrated to. Most likely it's the Sierra MatchKing. The TTSX should come very close to a match for BC. If you use a trajectory calculator that accepts G7 ballistic coefficients instead of just the standard G1 coefficients, you get around having to mess with the number changing at different velocities for most boattails. The G7 BC's for the 168 SMK and TTSX are 0.218 and 0.222, on average, as measured by Bryan Litz on identical setups. There are free online calculators at the JBM ballistics site that will work with G7 BC's.

If you switch to a higher energy, slower burning powder than Varget, even with the missing powder space, you should, theoretically, be able to go a bit faster when you hit the same barrel time that your sweet spot is located at. Either Alliant Reloader 17 or Alliant ARComp powders appear capable of adding at least 50 fps at the same barrel time if not a bit more. You'll get more muzzle blast, too, but your ballistics will be closer to the sight knob. Use Winchester cases for maximum capacity (though I saw recently that some Hornady cases may also be in the same capacity range as Winchester; just haven't seen for myself yet).

If you can't change velocity, it appears to me, starting with a 100 yard zero, that you will have to use the sight knob come ups plus add an additional:

0.3 moa @ 200 yards
0.8 moa @ 300 yards
1.1 moa @ 400 yards
1.7 moa @ 500 yards
2.3 moa @ 600 yards
3.0 moa @ 700 yards
3.8 moa @ 800 yards
4.8 moa @ 900 yards
5.8 moa @1000 yards
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