Anyone know of a good one? Have a 6933 upper and want to keep the FSP.

Interested in any options out there as well.

Geissele used to make one and Strike Industries used to I think too.  Not sure if anyone does currently.

https://www.ar15.com/forums/ar-15/-OFFICIAL-FSP-Cutout-Extended-Handguard-Rail-PIC-thread/12-681826/?page=4

Those are neither KeyMod nor M-lok...

Maybe, looks like m lok to me, but I could be wrong.

Geissele does not make FSP rails. The rail in pic above has been modified.

If you keep an eye on the EE, you'll occasionally find the Fortis Rev cutout rails on there.  I had one on a rifle for a good while and loved it.  My other sticks still have Fortis Rev rails, but I unfortunately (and am kicking myself) sold that upper a good while ago.  I'd have sworn that Centurion, Apex, and Samson did cutout rails in keymod or mlok, but apparently I was wrong.  They do cutout rails, just not in keymod/mlok.    Worst case, the Fortis rails are incredibly easy to modify for it though.

I'll do some more thinking and see if I can come up with other options.

Centurion makes one

https://www.weaponoutfitters.com/centurion-cmr-cut-rails-5711.html