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


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Eustachius234
August 20, 2009, 01:08 AM
Will the BDC that comes with the Leupold Mk4 3.5-10x40mm LR/T M3 Front Focal (http://www.leupold.com/tactical/products/scopes/mark-4-lrt-riflescopes/mark-4-3-5-10x40mm-lrt-m3-front-focal/) work with .308 Win Federal Match 175gr and a Remington 700 XCR Compact Tactical (http://www.remington.com/products/firearms/centerfire_rifles/model_700/model_700_xcr_compact_tactical.asp)?

My concerns are really two-fold:

The BDC that comes with the scope does not offer the 175gr option.
The velocity generated out of the 20" barrel is insufficient to be compatible with the BDCs calibrations.

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1858
August 20, 2009, 01:38 AM
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, 59F and 29.53 in.Hg.

:)

Eustachius234
August 20, 2009, 01:53 AM
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.


Does that mean that the elevation knobs work independently of the BDC?

1858
August 20, 2009, 02:02 AM
Does that mean that the elevation knobs work independently of the BDC?

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.

http://128.171.62.162/hawthorn-engineering/thr/optics/leupold/mark4/bdc.jpg

:)

Eustachius234
August 20, 2009, 02:05 AM
Thanks, that clears it up some in my neophyte confusion.

1858
August 20, 2009, 02:22 AM
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.

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



:)

Eustachius234
August 20, 2009, 02:35 AM
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?

1858
August 20, 2009, 03:18 AM
The Leupold Mk4 3.5-10x40mm LR/T M1 Front Focal seems the way to go.

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.


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?

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.

:)

Eustachius234
August 20, 2009, 03:23 AM
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?

1858
August 20, 2009, 03:36 AM
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?

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.

:)

Eustachius234
August 20, 2009, 03:42 AM
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.

1858
August 20, 2009, 04:11 AM
Anytime ... just PM me if you have any other questions specific to the Mark 4 line.

:)

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