Start simple and build on what you learn.The best scope for bracketing in Hunter Division is one of the UTG 3-12x44 swat scopes with the wire reticle. Either compact or full length. But you can use any scope with constant stadia markings.Set your scope at the magnification that you intend to use. You'll need to be able to exactly repeat that setting if you ever move it. If it's a 12x scope (preferred), just max it out to the stop. Pick a target feature that you might encounter. Cinder blocks are used often enough that it is a good one to learn. It is also sufficient in size to get a good estimate on a far target. A Cinder block is 7.625 inches wide. That's the horizontal distance that you usually see when a target is clamped to it. If you don't have a block, make a paper target that is that wide.Start at 55 yards. Place the target at 1 yard increments and read how many dots go across the block. Not so easy as it sounds, but when you get good, you can read to the nearest .1 dot space. You'll learn to scan your eyes back and forth while avoiding the natural tendency to also shift the scope back and forth. Make a chart with the distance vs dot span.With the above method, you can get good dope without knowing your scope calibration. Scopes are rarely exactly 12x, but it does not matter with the above method. If you can read to the nearest .1 dot, you will be able to bracket an exact size, straight-on, standard size cinder block within a yard.If you are good with spreadsheets, you'll find them very useful for expanding your bracketing skills and dope.It can be as simple as that, or it can get as complicated as you want to make it. You won't always see a suitable cinder block, so you'll eventually want to learn other features. And you can always fall back on focus range finding.
...Would doing it empirically at shorter ranges and "calculating" it to the longer ranges be a fool's errand?
Thanks Scott. I have my wheel marked for better or worse for focus-ranging, so I may be able to get some bracketing data at say 10 yards for the CMU at 7.625 and math it up to 55-40.
Quote from: TwiceHorn on June 03, 2017, 08:11:45 PMThanks Scott. I have my wheel marked for better or worse for focus-ranging, so I may be able to get some bracketing data at say 10 yards for the CMU at 7.625 and math it up to 55-40.At 10 yards, you will run out of mil-dots (>20 dots). So you will need to bracket in mutiple stages.Then "math it up" to your 15 yards and see if it matches the actual dot count (16.9 dots) at 15 yards. If you are lucky, it will match exactly. But, it might be off a little. If so, when you "math it up" the 55-40yds, you'll be even farther off. That's where accounting for your scope calibration comes into play.
...I see that on the mildots, yes. Funny how myopic you get doing this (I don't "see" anything bigger than about 3/8 in my scope under 20 yards). Would a fudge factor coefficient, say measured at 16.5 at 15 yards, of measured/calculated 16.5/16.9, be "linear"? Or would that propagate some error I'm not thinking of?
Quote from: TwiceHorn on June 03, 2017, 10:11:20 PM...I see that on the mildots, yes. Funny how myopic you get doing this (I don't "see" anything bigger than about 3/8 in my scope under 20 yards). Would a fudge factor coefficient, say measured at 16.5 at 15 yards, of measured/calculated 16.5/16.9, be "linear"? Or would that propagate some error I'm not thinking of?There can a base calibration error that is linear. But that would have shown up at 10 yards first. i.e. - the scope may really be a 11.7x scope, hence the 16.5.If +/- 2yrd precision at 50 yards is good enough, it might not matter. If you want +/- 1 yd, you should account for all errors.There are a couple errors that you may not have taken into account yet.So I should ask - How are you measuring the target distance? Tape measure is best. And also, from what point on the gun are you measuring the distance?
...Ah, how precise. The 64K question....
You might want to take a peak at the reticle on the Athlon Talos 4-14X44 FFP scope. Each little hash mark is 0.2 mil. Might be a little easier than trying to guesstimate 0.1 mil. Athlon has other scopes in their line that also use this style of reticle. Beware though, they might not focus close enough for field target, or in some cases, don't have 12X engraved on their magnification ring. I think the Talos 4-14X FFP does have a 12X setting engraved on the ring.Zero experience in bracketing, but I'm interested in trying it and this reticle caught my attention.More information here:http://athlonoptics.com/wp-content/uploads/2016/05/ATHLON-APLR2-FFP-IR-MIL-Reticle-Manual.pdfhttp://athlonoptics.com/product/rifle-scopes-talos-btr-4-14x44-aplr-ffp-ir-mil/
"Do you have a full-dot or half-dot reticle?"I use a full Mil-dot reticle, but using12x mil-dots. UTG does not make a 1/2 Mil-dot reticle. I can split the distance between dots easily/precisely. So 1.5 dots is fast/easy. When ranging, I try to avoid the first 1/2 space near the center as it takes a little more thinking to read precisely. Though you do need to use it when doing holdovers."I have the full-dot UTG 8-32, so it has a hash at 1 and a dot at 2. I think I prefer the hashes."I prefer dots for ranging. The hashes lack some key reference points (0.9 and 1.1). When reading dot spans the X.0, X.1, X.5, X.9, are almost gimmes. And the full size dot makes it easy to gauge 0.2 jumps."Eyeballing 10ths seems like a tall order."0.1 Mils is the standard for normal proficiency. Expert snipers would be going for 0.05 Mil-dots. Since we are using 12x rather than 10x, our 0.1 mil-dots are actually giving us 0.0833 Mils. So we are striving to be a little better than normal (0.1 Mils) on our reads, but not necessarily expert (0.05 Mils)."The basic concept 1/1000 is fine, but MOA of course lends itself to inches/yards much more easily."Actually the 10x/12x dot spacing that we use in Hunter Division lends itself well to inch targets and feet distance. There are 12 inches in a foot. At 12x, a mil-dot spans 1 inch at 100 feet distance. The 1/100 mil-dot math is as simple as the 1/1000 Mil-dot math. It can be done in your head when you think in terms of inches and feet, but I prefer to do it all with dope sheets (charts) as it avoids the confusion that we can experience under match conditions. And the MDCF that deviates significantly from 1.000 and that we so carefully measured would be difficult to utilize without a calculator. Only when I have no other option, then I'll resort to head math for an estimate."Also, as a minute of angle is a smaller unit, there tend to be more stadia on an MOA reticle."True, but the MOA will still need to be split up into at least 1/3rds in order to have the same precision as our 0.1 dot estimates. Too many lines makes the process slow and error prone. UTG uses an extended Mil-dot reticle. The only feature I wish they would add is a hash across the 5th dot in each quadrant. That is where a standard Mil-dot reticle normally ends. Having an obvious 5th dot would speed up/simplify dot counts quite a bit.