SFP scope mapping?

[Vamike9]

I am somewhat new to long range precision but want to know if a SFP scope would really hurt my performance in tactical comps? I realize that it depends on many factors like scope mapping, ballistic calculators, and other things. Yet, my main question is, with all the tools we as long range shooters employ, would a SFP scope really matter? For years snipers have used SFP scopes to great effect, right? Aren't most long shots taken with the magnification on high, where a SFP scopes subtentions are correct anyways? Also doesn't Applied Ballistics calculator take SFP scopes subtentions into account? How do I map my scope properly? Sorry for all the questions but I hope this discussion will be helpful to many others as well.

 

[7magcreedmoor]

The answer to "does it matter" is both yes and no. Using a SFP scope for wind holds and distance holdovers can work just as well as FFP, as long as the operator doesn't lose track of where the mag is set. Mapping your scope is something you must do with great attention to detail, watching how the adjustment works from either end of the range. Internal play in the parts (and there has to be a little play or you couldn't turn any of the adjustments, but too much can be a problem) must be quantified. Like using a side parallax knob, you need to turn the mag ring the same direction each time, i.e. always go from lower to higher, or always go from higher to lower, so that you land at the same spot. Test firing to see if point of impact shifts after recoil when adjusting from one direction is a must do item. Example: you change mag from lowest setting up to some medium setting and shoot, getting a nice tight group. Then you go to the max and come back down to that setting again, and shoot a sloppy group. Now you know which direction to make all your mag adjustments to ensure good performance. Measuring your reticle against a very carefully constructed calibrating target to find exactly what mag setting doubles the subs, what setting triples them and so on is homework you need to do. Some folks go with FFP to eliminate those opportunities to screw up when shooting, but that doesn't mean you can't use SFP very effectively.

 

[Vamike9]

Thanks for taking the time to explain this information. My NightForce seems to be calibrated to very exact standards, half power mark is exactly half and full power is exact as well. I know this is not true with all scope manufacturers. I usually use a carpenter's level and a ruler when checking calibration on ffp and sfp scopes; yet, where are the most affordable targets that accomplish this with less time?

 

[Capt RB]

Best/cheapest target would be a roll of butcher paper cut to length needed. Take a 4' ruler or sheet rock square and a framing square. Mark out the increments you wish to use. Another option is the hours vision cat targets. A bit spendy but they are good