Help dialing in MOA second focal plane scope
 

Well it's taken me forever and a day but I finally have my 1st and probably last 1/2 long range set up .After my Remington 700 classic in 300 Weatherby gave up the ghost I pinched Penney ,sold my children's inheritance (lol) and got a new Remington 700 sps stainless in .300 rum free floated the Tupperware stock installed a Leopold 20moa Mark 4 Steel rings drilled and tapped the 6-48tpi with #8/40 screws and a pair of high Leoupld steel quick disconnect rings and I know Iam going to get a bunch of flak about my scope choice.I mounted a Minox zx5i5x25x56 second focal plane scope.I love the optics eye relief and huge field of view but it has a second focal plane reticle and is set for 1/8"moa @100yards .I can use the built in bdc ,which according to Minox tech says the reticle is set up for 300 win mag 180gr ,@2900fps This works for me with the hold over on steel rams at 500 meters ,but eventually I would like to stretch out from 500 meters to 700,and incremental in 100 meters steps out to 1000 meters,can I do this with this scope?If so any links so I can read up on it?To be honest I won't be able to afford another scope and Iam more of a hunter 1st and secondly getting into long range target shooting.Also Muzzle brake is going on this month,I have done a lot of medium range shooting by today' standards out 600 yards on game with my Weatherby but it was only with Kentucky bondage usually setting up 3"@100 yards and taping a drop chart on my riffle butt for holdover but nowdays .Long range shooting has become so precision oriented, and i would like to learn how dial in my scope for no holdover is this possible with my setup?



+ QuoteReply

I'm also interested in long range shooting and plan on purchasing a rifle soon. I'm also no expert on scopes but I have used the BDC type reticles for a while now. So with that being said, unlike first focal plane scopes the BDC reticle on a second plane scope is set up to be used at the scope's highest magnification. Now if you want to stretch that yardage to use, say the last (bottom) aiming point for 600 or 700 yards you can dial down the magnification until your bullet impacts where you want it and either mark the scope or make a note of the magnification position.
You may find that at a certain magnification point your BDC's aiming points may change from 100-500 yards to 300-700 yards. Just guessing. And if so that would be great for your 300RUM if the ballistics will allow you a 300 yard zero.
It would be interesting to hear your results.

why not just get a scope with an MOA reticle and use it at the highest power?, I shoot loopys with TMR reticles mostly but just use them to measure antlers. I dial my shots.
RR

how much up do you have left in the scope? do you have enough to make 1K, I assume so since you have 20 Moa rings or base. download an app on your phone set the turret adjustment on 1/8 Moa and have at it, it ain't hard.
RR

I was going to give you advice along whatRR has. Try looking on the Minox web site or app they may have the varying power mark spreads there for you. My friend has a Nikon and they give you the BDC at different power settings as does Swarovski. Give it a try will be a big help.

thanks for all the help boy I did not realize Ambien effected my cognitive skills so much,sorry for the confusion.Yes I need learning how to dial in the scope and ditch the substensions .Which o figured how to use at 550 yards at steel rams.Like I was saying Ian a hunter 1st but I would like to work towards some presicion long range during off season.Yes I have a very basic understanding of ballistics and handloading,but my no means am I a class f competitor. I know how to do metal work from experience as astructraul mechanic/backshop fabricator.I can't afford a new scope at this point.

the 20 Moa sloped base will allow you more up adjustment. center your reticle, then turn it down 20 Moa.and it should be close to zero. I zero my rigs all in at 300, thats around 1.75-2.3" high at 100 yards.
RR

I feel like it's trying to tell us something... :s2:

Are you asking how to zero your scope, or how to establish DOPE to be used to dial your scope for shots instead of holding over?

I'm a little surprised by either question - you knew to buy a 300RUM, tap over-dia mount screws, install the 20MOA base, understand the difference in first and second focal plane, but then need help either zeroing or establishing a trajectory to let you dial?

Messing with correcting the BDC reticle across various magnifications is a losing proposition. You have to remember irregular subtensions and then work with scaling factors... For hunting, this just doesn't work - too many moving parts. At the range, the time is there, but it's still a massive pain in the @ss. You CAN look up the subtensions at the reference magnification (it's not always the maximum), then scale them based on your magnification settings, but it's really a fool's errand. You MUST do an actual scaling measurement of your scope, because not all scopes are TRUE to their magnification settings - in other words, 5x vs. 25x might not actually be 5.0 times zoomed, which means you cannot simply take the target size read at one magnification and multiply or divide to get to the other... You MUST know the actual relative magnifications for your zoom settings.

The Minox z5 5-25x uses 15x as the reference magnification, NOT maximum magnification. The subtensions for the reticle are found in the owner's manual, available online.

You WILL be better off to completely give up on the BDC reticle and simply dial... So... To get your trajectory...

Go shoot across a chronograph, get a proper velocity for your load and rifle. Look up the BC for your bullet, and google trued values for the BC to be sure you have good info. Download the Advanced Ballistics App, enter accurate environmental data, enter your load and rifle info... It'll kick out a base trajectory.

Shoot at various known distances, dialing the prescribed drops, and record your actual drops. You can input these as truing values to the calculator, which will adjust your muzzle velocity. When you change environmental conditions, you change it in the app, and it'll kick out new corrections.

You can't get away with taping a range card to your stock without understanding how environmental conditions change the outcome. A headwind vs. a tail wind can mean a difference in your elevation dial. A strong side wind can also mean a difference in your elevation - let alone your wind drift. Temperature changes can speed up or slow down your muzzle velocity, and can change your density altitude enough to also make a difference in your elevation corrections. I shot a match yesterday, we started shooting at 24degrees and ended at 55 degrees, and we went from shooting into a 13-20mph headwind to only 1-3mph. The data I used in the morning was a half mil lower (~1.5moa) at 600yrds than the data I used midday. Shooting at 8" targets, I would have completely missed the target if I had not corrected for the temperature change.

Get a data book and the AB app (or strelok), and get familiar with your rifle's trajectory, and how it responds at different temperatures and in different winds.

Good golly NoMercy - I think I'll give up that long range venture I was thinking about and just see if I can find some heat seeking bullets to load up for hunting at extreme ranges!!
My brain is just too old to do all those calculations. Heck its hard enough to coordinate looking through the scope and squeezing the trigger!

If I can do it anybody can!
RR