[JTinIN]

I got a rail mount on the MM23eK and was also looking at the Vortex Viper PST 1 to 4 and the Burris MTAC 1x4, along with the Elcan Spectra DR for too much more ($1800).
Would be interested in what you decide on.

When setting up the scope, if you remove (or don't have installed) the rear sight, then can get a lower scope mount. Have to watch some of the AR type mounts, as most raise the scope to the proper height for an AR with it's straight stock. The higher scopes work ok with a stock having a raised cheek piece, however, is a personnel preference issue.

 

[JTinIN]

I went through this a few weeks ago. Whether 4x will provide enough magnification depends upon your eyesight and the distance to target. I am 58 years old and will be shooting up to 250 yards so for me 1-4x was not enough. I went with a Vortex Diamondback 3-9x (about $200) and I'm very pleased.

Plus of course the size and contrast of the target. Always figured ten power was more than enough, until started shooting the 5.5x22 on the Sako TRG42 338LM and after a few days was reaching up to raise the power even though it was at max ;-). Have done ok with an aim point at 300 yards but were just shooting balloons, plus the "fun switch" was used at times.

 

[JTinIN]

You may find that the front sight is not an issue, however, one option for a semi custom build is to remove the front sight and the rear sight base, then add rails at both locations, similar to what one of the guys did for his MM23eK. If you wish to have BUIS then there are several lower height folding front and rear iron sights for the HK 4xx series of guns and similar raised rail guns, that may work (have not tried myself).