I am trying to determine what mount to purchase for my pending ATACR on a SR25.

My MK5 is currently mounted in a SPUHR 4002.  The ocular lens is just a touch behind the charging handle, probably within 3/8ths-1/2 inch.

I would like to have the ATACR is more or less the same place, however it appears that the turret assembly is a bit further forward on the ATACR versus the Leupold, but I cannot find anything on Nightforce's website that provides dimensions on the optic as a whole.  

Per Leupold's website, it appears the distance from the ocular lens to the rear of the turret assembly is 5.3 inches.  The turret assembly is 2.2 inches long, putting the front of the turret assembly at 7.5 inches from the ocular.

Can someone provide similar dimensions to me for the ATACR?  I ordered a 4002-c for the optic, but can return it if I need a cantilevered option.

Alternatively if you have both and can snap some photos, that would help, or just share what mount you use with your ATACR 5-25 on your SR25.

Different optics; different specs.

Who cares if both your scopes stick out over the receiver the same distance?  You should probably just lay down behind the rifle once you get your stock setup for proper length of pull and then put the optic whatever distance from your eye it needs to be for ideal eye-relief and maximum eye box... don't forget to check at both 5X and 25x because they could change a bit based on their zoom.

3/4 of the way down: https://www.optics-trade.eu/blog/nightforce-riflescopes-atacr-instruction-manual/

Thank you for the link, unfortunately its missing a few dimensions which would help me really dial in certain measurements.

Regarding your first point, all of my magnified optics on gassers are in roughly the same place- this general location has worked well for me and given me a place to start.  Most mounts allow for some wiggle room front to rear, but at the end of the day, I need a place to start hence the post.  The 4002/MK5 is as far forward on the gun as it possibly can be, there is no more room to move it forward.  It is also as far to the rear as I like my optics to be, short of some hilariously large eye relief change...and both are pretty damn close.  So again, simply a starting point so I don't have to try multiple 3-500 dollar mounts depending on availability!

Long short, if the ATACR's turret assembly is any further forward than the MK5, I will need a cantilever mount of sorts to make it work the way I want it to.  

The pictures are likely of the actual product with labelled linear dimensions.  Just use photogrammetry to determine the missing dimensions. MSPaint is good for this.