D&D Gunworks note:

This is an optics mount that replicates the one used on the M40a1, this will fit all Remington 700 Short Actions that have been clip slotted.   In addition the rings are 1in meaning that just about any optic with a 1in tube and 40-50mm objective lens will work, no need to have a Unertl or MST100 just yet.  These are the same mounts that we use on our M40a1 USMC version with clip slotted receiver.  The screws have been changed from the original thread patter to 6-48, we did this for several reasons.  6-48 became the standard scope ring screw and we wanted to make to easier on the builder.  We also removed the issue of the screws being close enough to cause damage to the receiver holes of the Remington 700 that is also 6-48, and last we never wanted our parts to be passed off as original.  With a company owned by a former 2112 and a former 8541 Scout Sniper we wanted to keep the value of the originals alive, we are in the market of preserving history not faking it.  While these were an over 2 year project to bring to market we are ecstatic with the way they turned out and are proud to put our name on them!  This mount is in the white meaning the steel has not be coated or treated.  If you are going to finish all your parts and you want to fit everything before hand this is the best option.