Question about mil-dot reticles and magnification

[Strakele]

I'm about to buy a scope with a mil-dot reticle. I read somewhere that in a variable power scope, this reticle is not accurate (as in its range calculating abilities, not actually aiming the rifle) except at the highest magnification. Is this true?

Thanks.

 

[rcmodel]

It depends on whether it is a first focal plane or second focal plane reticule.

Most scopes use the latter because folks don't like the crosshairs getting smaller and almost invisable at low power, and huge at high power.

With the former, the mil-dots stay the same relative to distance and are really "mills" at any power setting, but become almost invisable at low power, along with the reticule.

Nightforce and some others use first focal plane. Leupold, Burris, and most others use second focal plane.


rcmodel

 

[Strakele]

Ok thanks for the info. I've been looking at getting the Bushnell 3200 Elite 10x40 mil dot scope. I've read good things about it and it seems it will suit my needs. Then I started reading about parallax and all that and started wondering if there was something better I could get. I'm looking for a mil dot scope in the $200 range. Are there any others than the Bushnells? Do the variable power Bushnell scopes use first or second focal plane? Which would you recommend?

Thanks for the help.

 

[rcmodel]

Just about all the American branded scopes use second focal plane.

I suppose the Bushnell is as good as you will find in that price range.


rcmodel

 

[rero360]

isn't there a formula that allows you to use the mils at any power?

 

[Clark]

t depends on whether it is a first focal plane or second focal plane reticule.

Most scopes use the latter because folks don't like the crosshairs getting smaller and almost invisable at low power, and huge at high power.

With the former, the mil-dots stay the same relative to distance and are really "mills" at any power setting, but become almost invisable at low power, along with the reticule.

Nightforce and some others use first focal plane. Leupold, Burris, and most others use second focal plane.


rcmodel

Nightforce is now coming out with a first focal plane scope.

http://accurateshooter.wordpress.co...t-focal-plane-nightforce-35-15x50mm-f1-scope/

Leupold has a couple FFP models that also came out this year:
http://www.longrangesupply.com/index.php?main_page=product_info&products_id=175

 

[sscoyote]

"isn't there a formula that allows you to use the mils at any power?"

Yes. U can use any multi-stadia reticle to rangefind with, simple plex, ballistic, rangefinding, whatever. Here's the formula (inches to yds.)--

tgt. size (") x range of reticle subtension measurement (usually 100 yds.) / reticle subtension (") / quantity of gap tgt. occupies(decimal equivalent) = range (yds.)

...looks complicated, super-simple to apply. Suppose u have a 3-9x Leupold VX-III plex reticle that measures (subtends) 5.4 inch per 100 yds. between plex post tips, and u want to range a 10" steel silhouette that occupies 1/2 (.5) the reticle gap (x-hair to plex post tip). Here's the equation--

10 x 100 / 5.4 / 0.5 = 370 yds.

see how it works?

 

[sscoyote]

Just another comment on mil-dots and rangefinding. The mil-dot in a 2nd focal plane optic is actually more accurately applied at a power higher than what it's clibrated for if it's cald'. for a power lower than the highest.

My 6-18x Nikon Buckmaster's scope with MD is cald. for 12x. At 18x It's 66% smaller at 2.4 inch per hundred yds. As magnification is INCREASED reticle subtension DECREASES, so the system is inversely proportional (12 is 66% of 18). Though it's not a perfect system it'll often astound you at how accurate it can be.

 

[Netz]

As sscoyote said, if you have a varible power scope with mil dots, the manufacturer should state at what power to set the scope at to get the proper mil dot reading.
Curt

 

[BornAgainBullseye]

If you were that worried about being accurate then back it up with a laser. Mil dots while better than others still has its downfall. If you have to guess the size of the target then you are usually wrong. Just get on the bullhorn and shout at that armed insurgent to stand next to a yard stick so you can get a proper firing solution on him. I use them for to get a general range. When it has to count I bust out the laser.