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Leupold Mk4 3.5-10x40mm LR/T M3 Front Focal BDC

Discussion in 'Rifle Country' started by Eustachius234, Aug 20, 2009.

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  1. Eustachius234

    Eustachius234 Member

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    Last edited: Aug 20, 2009
  2. MCMXI

    MCMXI Member

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    Any BDC dial is going to be approximate (ranging from dead nuts on to way off) even if you're shooting the bullet weight indicated on the dial. You can always have Leupold make you a custom BDC dial for around $60 for your bullet weight, muzzle velocity and "typical" operating conditions. But even then, if you're density altitude changes significantly you're back to an approximation at best. I have BDC dials on two of my Mark 4 scopes but to be honest, I don't really use them. I generate ballistic data cards for all of my loads and use that data.

    A BDC dial is useful if you don't have any DOPE at all I suppose. At least it might get you close, and maybe very close. The 168gr BDC dial on my 3.5-10x40mm M3 is very close to the Federal Match 168gr HPBT SMK data with a MV of 2600 fps at Standard Metro Conditions (SMC) but I don't typically shoot at 0ft altitude, 59°F and 29.53 in.Hg.

    :)
     
    Last edited: Aug 20, 2009
  3. Eustachius234

    Eustachius234 Member

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    Does that mean that the elevation knobs work independently of the BDC?
     
  4. MCMXI

    MCMXI Member

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    No ... it just means that the bullet drop scale (top) on the dial can be ignored in favor of the standard MOA markings (bottom) on the dial. The M3 scopes have fairly coarse (1 MOA) vertical adjustments so depending on your particular situation, you may want to have more detailed ballistic data rather than simply relying on the BDC dial.

    [​IMG]

    :)
     
  5. Eustachius234

    Eustachius234 Member

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    Thanks, that clears it up some in my neophyte confusion.
     
  6. MCMXI

    MCMXI Member

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    Here's a comparison of Federal Match 168gr and 175gr ammunition along with the BDC values that come standard on the Mark 4 168gr BDC dial ... interesting. This data is based on SM conditions. The 3.5-10x40mm M3 is an excellent scope for specific types of shooting. It should be obvious from the data below that it's not an ideal scope for every type of long-range shooting discipline.

    Code:
    	RANGE	Elev.	Elev.	168gr BDC
    	(yd)	MOA	(in)	   MOA
    168gr	100	0.00	0.0	    0
    175gr	100	0.00	0.0	    0
    				 
    168gr	200	2.00	-4.0	    2
    175gr	200	1.75	-3.9	    2
    				
    168gr	300	4.75	-15.0	    5
    175gr	300	4.75	-14.6	    5
    				
    168gr	400	8.25	-34.2	    8
    175gr	400	8.00	-33.2	    8
    				
    168gr	500	12.00	-63.0	    12
    175gr	500	11.75	-60.9	    12
    				
    168gr	600	16.50	-103.4      17
    175gr	600	15.75	-99.4	    17
    				
    168gr	700	21.50	-157.5	    22
    175gr	700	20.50	-150.3	    22
    				
    168gr	800	27.25	-228.0	    28
    175gr	800	25.75	-216.0	    28
    				
    168gr	900	33.75	-317.8	    35
    175gr	900	31.75	-298.9	    35
    				
    168gr	1000	41.00	-430.4	    43
    175gr	1000	38.50	-402.0	    43
    
    
    :)
     
    Last edited: Aug 20, 2009
  7. Eustachius234

    Eustachius234 Member

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    The Leupold Mk4 3.5-10x40mm LR/T M1 Front Focal seems the way to go.

    Question, why would anyone go with the Tactical Milling reticle over the mil-dot, when it seems that you're meant to dial in distance & windage anyways and therefore the rest of it seems to be a lot of unnecessary confusion?
     
  8. MCMXI

    MCMXI Member

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    I have that exact scope and really like it. It sits on an AR-15 that I use at 200, 300 and 600 yards in matches ... it's a great scope.


    All of my Mark 4 scopes either have the tactical milling (4) or special purpose reticles (3). The TMR gives you more precise holdovers for wind and elevation in situations were you don't have time to make corrections with the turrets. Also, you have the ability to range objects with greater accuracy compared to the mil-dot reticle. I would strongly suggest the TMR and there's nothing confusing or cluttered about it. In fact, many high end scope manufacturers are offering TMR equivalents now.

    :)
     
  9. Eustachius234

    Eustachius234 Member

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    I just noticed that the 10x40mm M1 has 90 MOA of elevation compared to the 65 MOA for 3.5-10x40mm M1, I take it this means that it can adjust upwards further and therefore can make longer shots?
     
  10. MCMXI

    MCMXI Member

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    That wouldn't even be a consideration for me. A 20 MOA canted base will give the 3.5-10x40mm M1 more than +50 MOA elevation which is more than enough to get out to 1000 yards and beyond with a .308. Also, all of my Mark 4s have more elevation and windage travel than advertised. For example, the Mark 4 8.5-25x50mm LR/T M1 Illum. scope on my .300 Win Mag has 84 MOA of vertical travel (verified) compared to the 75 MOA advertised.

    :)
     
  11. Eustachius234

    Eustachius234 Member

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    Thanks you answered my last two questions - until I come up with more - whether they'll work with a 20 MOA base & can they get out to 1,000yrds - not that I can:(

    1858: Thanks a bunch, you really satiated my hunger for knowledge on this subject.
     
  12. MCMXI

    MCMXI Member

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    Anytime ... just PM me if you have any other questions specific to the Mark 4 line.

    :)
     
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