I have a couple of Mausers opened up the usual way with the front ramp below the lower locking lug abutment ground away. However, for those 'smiths that have modified the bolt stop to accommodate a longer cartridge, would you happen to have a photo of one? Wondering how much you can take off and it still function. In other words, photos of a Mauser opened up from the rear of the action.
Thanks in advance.

Yes, that is the way I do it and that does reduce the amount you need to remove from the lower locking lug seat a lot. I often make a new magazine box rear panel, and mill the bolt stop back. How much? There is a little flat place on the bolt stop; you can easily remove all of that. The thickness of the mag box rear panel at least. Doesn't sound like much, but you are adding that much to your lower locking lug seat/feed ramp where it counts. I have no photos as I don't have any of those in here right now.

1 mm or .040" of an inch is the most I remove from the bolt stop to increase the rear travel.

Be advised to really check the bolt stop over well for battering, many of them are somewhat soft and those you should not rework.

J Wisner

Don't know if this helps but images of the action rear on my opened up Mauser for the 404 cartridge.
Note the second photo shows the gap at the front of the magazine follower with it hard back in the magazine box where it naturally sits, and all that gap didn't come off the feed ramp.