BDC, Hold Overs, Etc.

[outerlimits]

ok, say you got a scope with a BDC reticle. say you dial it in so your loads are close to matching the BDC points. say the BDC points are 200, 300 & 400 yds. now the conundrum...targets are say 270 and 360. how do you figure the holdover points given the "tweeners"?

i have always looked at the trajectory tables for the target distances, compared the drops to the known drops for the BDC markings and then it becomes a guessing game on how much to hold over. say the 360 yd target had an extra 8" drop from the 300 yd BDC point. you hold 8" low of that target (think bottom of the plate). or is there some voodoo magic i'm missing on the in-between points?

[jdknotts1]

If you have a smartphone, get the strelok app. Very nice app and it shows exaclty where to hold between the stadia

[landshark45]

Unless your shooting tiny lil targets the overall size will make up for any reticule estimation errors.

[Heshin]

If you have a smartphone, get the strelok app. Very nice app and it shows exaclty where to hold between the stadia

^ This will get you real close!

[benny hill]

That's why you have a hi-cap mag.

[Dan Sierpina]

On your 360 yard example, hold the 300 yard bar/dot at the top of the plate. It doesn't hurt to use JBM Ballistics and set the output to 10 to 25 yard incriments.

Butch, did you find powder yet?

[outerlimits]

always used the JM and istrelok on my iphone. just thought there was a better way of estimating the hold. and yes, benny, that's why they created a beta mag. dan-just got shipping confirmation on some BO powder, so won't be long.

[jdknotts1]

always used the JM and istrelok on my iphone. just thought there was a better way of estimating the hold. and yes, benny, that's why they created a beta mag. dan-just got shipping confirmation on some BO powder, so won't be long.

Can't quite imagine any better way to estimate a hold than a picture of your reticle with a bullseye showing you where to aim.....

[Jesse Tischauser]

A lot of balistic programs have a vital zone size or a target size input. If you put in 10" diameter like the MGM flash targets. The program will give you a range of distances that your bullet will hit the 10" window if you aim dead center on it. You will be suprised at how much range a particular hold will keep you on target. Your bullet may impact a few inches high or low of center but it still gets a flash on the MGM target.

Come to think of it the MGM falsher is 15" top to bottom. If you start talking LaRue targets or those big full size IPSC steel we shoot at Rocky Mountain or Fallen Brethren when shooting past 300 yards, you almost can't miss on the elevation side of things.

Edited February 28, 2013 by Jesse Tischauser

[Jeff F]

Jesse is right here with input of 10". I like to use a 5" input to get as close as I can

[Lead-Head]

Yep. With my irons rifle, I zero at 300yrds. If all I shot at were MGM flashers, I could hold on the steal from PB out to 340 yrds or so.

[9X23Guy]

All of this is great advice but you MUST chrono before you do anything or all of this is still just best guess. Find the load you're going to use and get some data then use all of the above mentioned and you'll be good to go. Ammo is expensive, don't guess, know.

[goat68]

For me the answer is practice. I gotta get a feel for where the rounds land based on the off distance and BDC. Usually doesn't take long like less than a 100 rnds in practice. The distance in the stage description is only part of the equation. You will still need to deal with atmospherics, mirage, heat off the barrel, wind, terrain, and the worst thing to predict - what happens after the BEEP!