I must be slow...

What is the difference between the two?

In laymans terms.

Thanks!

M1 has 1/4 MOA clicks, meaning every click represents 1/4" at 100yds, 1/2" at 200 yds, 3/4" at 300yds, etc...

The M3 has 1 MOA elevation clicks, but the dials compensate for the trajectory of the bullet, so when you click your dial to adjust the point of impact you are really dialing in based on a trajectory of the selected cartridge.

The M3 makes for fast to target adjustments, you just zero it and when you need to hit 500yds you just dial up to the 500yd mark, and the bullet should be within 5" of that point of aim -- good for quick center mass hits.

There will be more detial forthcoming.......please hold. [:D]

M1= slow, precise 1/4" clicks

M3= fast, coarse 1" clicks

I have a Mark IV M3 that I really like.

Only at 100yds, right? [;)]

At 300yds the one click on the M3 will move you 3".

Yes 1 MOA = 1"@100 yards, 2"@200 yards, etc.  

The M3 is awesome for shooting at larger targets for center of mass.  I have a MK4 M3 on my PSS and it is great on gongs.  I bought a 4.5-14 LR M1 for another project. This will be for shooting smaller targets.  I am building this one for dynamite and reactive target shoots.

IDHunt

I also have a MKIV M3 on my AWC SWS.  Great for what I use it for.  If true precision is what you are after, then the 1/4 adjustments may be a better choice.  The foregoing does not take   into account the skill level of the operator.
Mike, NY

Thanks!

For my intended use I'll probably go with the M3.

Joe

Joe_556

Be aware that the M3 Bullet Drop Compensator (BDC) only works for a specific load fired at a specific speed.  If all you fire is factory loaded ammo, you should be fine.  I think the magic number for .308win is a 168Gr bullet at 2650 fps, but be sure to double check that.

I reload and have some .308win 168gr loads that are super accurate but are very slow at 2410 fps.  So, the BDC would put me in the dirt at ranges out past 400 yrds.  My 180gr 1000yrd loads don't reach 2600fps either and wouldn't work with a BDC.

I find the M1 is just about as fast as the BDC, if you keep a chart.  A balistics program doesn't hurt either.  But once you have your loads dialed in and your ranges checked, you look at your chart and turn the dial.  It takes a little more work to setup, but in my opinion it's just as fast in the field and allows for fine tuning.  At 500 yards, the M3 only allows you to move 5" up or down with one click.  The M1 allows you to move 1.25" up or down per click.

My only complaint about the M1 is the height of the target knobs.  They are a little tall.

-Red-

Custom dial from Kenton Industries for your load at your MV.

HTH....

The intended use will be for a 20"-24" AR type 5.56 rifle.  500yds will probably be the max yardage that I would ever encounter.  

Opinions?

Thanks!

The M3 is calibrated for specific barrel lengths.  You will want to verify if it will work for your rifle.

The M3 dials are basing their markings on muzzle velocity of a particular weight bullet.

As Troy says, I don't think you are going to gain or lose a material amount of FPS from one barrel length over another, especially in 5.56/.223.  The .223 dial is spec'ed to run a 55gr @ 3200fps or similar to XM193 or Q3131a.