Fitting new Shadow 2 Optic Ready adapter to the existing frame

[timmy75]

Bought a new S2 OR adapter (slide and barrel, the entire upper part of pistol).
https://prodejna.czub.cz/adapter-optics-ready-pro-cz-shadow-2#detail-anchor-description

Can't assemble it with lower part at all (can't even start). Slide rails are untouched. Existing slide has rails fine sanded to frame from factory.

From what I can tell I need to file/sand a bit off the outside edge of the rails and match it to my existing slide.

But I have never done such thing. Any advices before I ruin my new slide? Is it smart to do it first time alone or should I visit my gunsmith?

I did many CZ internals but never anything like this.

EDIT:
Adapter looks like this:


It is not my picture but it is the same like this. Even serial number is different in last digit only.

[2morechains]

I’ve had to fit a brand new S2 slide to an existing frame before.  Based on the measurements I took (measure 3x, cut once) I had to take about .008” off either side of the outside rails on the slide.  The other dimensions all looked OK.

I started with a small file w/ a safe edge for the coarse work.  Then switched to sandpaper on a flat block.  Finished with lapping compound I bought from Brownells (600 then 1,000 grit).  The key is to not do too much all at once. 

[SoCal]

  The key is to not do too much all at once. 

And take the same amount from each side.

[timmy75]

Done.

Diamond file first to remove nitride coating. Then normal file, fine sandpaper and polishing.

Had to remove 0,3 mm from each side (3/256 inch)

[coolbox]

How tight is the slide to frame fit?

[timmy75]

It is a tight fit. Like the old SIG P210.

We did one more for my friend, he wanted a "factory fit". Removed 0,05mm more from each side of that unit. Feels like the original slide under my hands. Booth pistol working flawlessly with factory and 130 PF match ammo.

Booth slides had 0,35mm too much material on each side. With 0,3mm removed from each side it is a tight fit and with 0,35mm removed it is a normal, factory fit.

You have to be careful not to remove too much and to remove exactly the same from each side. Otherwise you could end up fitting everything else

Booth pistols can shoot 50mm group at 25m and one big hole at 15m

[coolbox]

Thank you