Rifle Scopes Ranging with duplex reticle

[jayd4wg]

mounted a new scope for hunting purposes on another Marlin xs7 and I am wondering about the best way to range with a duplex 30/30 MOA reticle? I know this "thru the scope" pic sucks balls, there's a screen door with a bunch of 2 year old hand prints all over the glass between me and the "target" but it started the wheels turning.

Scope is cranked to 10x where the SFP reticle supposedly subtends 30MOA from post to post in both directions.

window in picture is assumed to be a standard size window for most of the homes in my area - about 45" wide.

at right about 12.5MOA, thinking this house is approx 340-350 yards?

turning this into a real world scenario, what is the best way to utilize this type of reticle on a zoom scope where the published height of posts might not happen at the exact specified magnification? I'd assume a target of known size be placed at a known range, and check against the reticle at various zoom levels, or better yet, have a partner mark a target at the proper locations for measurement of the actual reticle values to plug into a range card? All would work...what would YOU do? Smartass answers expected (like get a real scope with a mildot or other ranging reticle) but honestly, if the SHTF, and you did not have access to YOUR rifle, and you were stuck picking up my hunting rifles for protection...how would you manage?

Lets check my math - I measured this with Google Earth and i'm WAY off, the house is about 580 yards away. at 580 yards, the 45" wide window should occupy only 7.5 (7.41... (45 in. /580 yards)*95.5=7.41MOA) MOA...I think i need to hit the range with a known size target and analyze the size of the reticle for a bit and work out a couple range cards for deer sized game. average whitetails in my area are 15-18" shoulder to brisket. I can mark up which zoom levels = 15" at various distances. OR i could just say fawk it, sight dead at 200 and pull the trigger on anything out to 250.

and before we get any lip about the clarity on the scope...with the sun beating in the door on the objective, another view a few moments later of other items of interest at 10x zoom
http://lh6.ggpht.com/_jzCho0qN0Vs/THg-dYDkQ7I/AAAAAAAAFk0/wPDWFRSPZFY/s640/CIMG0347.JPG

 

[UserM4]

Re: Ranging with duplex reticle

Since there's no real ranging hash marks or dots or anything, it's obviously a terrible choice for range estimation and at best, not very precise. Since bullet drop can be very pronounced between short distances at length, I would give up range estimation with this reticle and either invest in a different scope or send the scope out to get a new reticle installed or even buy a range finder. Because, apparently, your estimation was way off even tho you thought you knew the window size and luckily found it to fit inside 12.5MOA of your reticle.

If you really wanted to use this reticle, you can probably set out a 30 MOA target at 100 yards with grids drawn on it for each MOA and mark your mag ring according to the grids as necessary.

 

[Lowlight]

Re: Ranging with duplex reticle

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">turning this into a real world scenario, what is the best way to utilize this type of reticle on a zoom scope where the published height of posts might not happen at the exact specified magnification? </div></div>

Buy a laser range finder and make sure you replace the batteries before going out that morning.

 

[GasLight]

Re: Ranging with duplex reticle

We shoot deer and antelope out to around 450, just using hold over with a duplex reticle. If you know your dope, you can estimate the hold with your eyes based on the 'known' size of the animal. This would work just as well with a person. If I know my bullet drops 3 feet at 450 yards, then I can reasonably estimate that and hold over. 500 yards and out becomes a whole new ballgame, when mis-estimating will easily translate to a miss, you need to know exactly what range your target is, and in my opinion using a duplex reticle will not give you that kind of accuracy.

Hope that helps

Dave

 

[Guest]

Re: Ranging with duplex reticle

Duplex's were used for many years to range with. While not the best, I've still a 2.5x8x32 on a 600 Remington .308

First you have to know what the scope subtends at all power setting at 100yds, then you normally use the scope in reverse order for bullet drop.

Lets just say at 100yds your top thin to bottom thin is reading 36" at your lowest setting so that give you 18" from cross hair ctr. to your thin top or bottom. Now turn the power up to max and check, you'll find your somewhere between 12-8" total max thin to thin you now have a built in BDC.

With the same target at 100 yds, turn your power ring and mark the scope tube as to the range setting. Place your bullet drop for different ranges on a card with power ring setting to match.

While not very good compared to today's world, it works and with practice it will get you minute of chest to 600yds with a .308 w/o issue.

If it were I, I'd save money and get something FFP in one of the three system out there or just do a LRF. The only problem I've found with using a LRF in some venues is while they are spot on, there are comps where they are allowed but just worthless weight. There are guys setting targets that know their limitations. So if your restricted to a shooting box, they place limbs in front of the smaller targets, which will put you out of your error range rather quickly.