There are lots of options being thrown out. I'm not sure how many will give you a low recoil load that you could use a rifle scope with on a pistol without a muzzle break. I think Ernie had a very good point here. Figure out a bullet and then a cartridge that will do what you want. To this end, I would recommend looking at bullets with low terminal velocity requirements that are commonly used in some of currently popular lower velocity or long range hunting rounds such as 300BO or 6.5 CM. I can really only speak knowledgeably about the Barnes offerings, but the Speer 120gn golddot that is used in the 300BO is suppose to be good at low velocities. Some swear by the Hornady V-max, but i'm not a fan of varmint bullets at deer at any velocity. I have heard folks say that some of these high BC 6.5 hunting bullets are really just relabeled match bullets nearly explode at close ranges so do some research.

Barnes has 2 offerings for the 300BO in their TAC-TX line with black tips. a 110 and 120gn bullet with BCs of 0.289 and 0.358. Barnes recommends a minimum impact velocity of 1450 for both of them in hunting situations (2x expansion at 1350). I am using the 110gn in 30-30 contender factory 14" barrel and can launch it at 2500fps which I consider max velocity due to pressure signs. At that velocity, I maintain ~1450fps out to around 400 yards. I ran the ballistics for the 120gn with an estimated MV (matched energies) and came up with the same distance. I think you could get a barrel in 30-30 AI or even 308 and load the 120gn bullet at ~2500-2600fps and have a great 400yd gun (albeit not real flat shooting) The 30-30 could be a contender platform but with an estimated MV of 2500+ with the 120gn projectile and no muzzle break I don't know if a rifle scope would work very well. I do think that such a setup in an encore with a 15" heavy or bull barrel would work very well. I know the 110gn bullet is a deer hammer out to 180yds.

Barnes has ballistics for 3 long range bullets (https://www.barnesbullets.com/wp-content/uploads/2019/03/VOR-TX_LR_Ballistics.pdf) . i know the 6.5 has a terminal velocity requirement of 1600. I'm not sure about the other bullets, but an email to customer service will get you an answer in a week or so.

The 95gn 6CM on their ballistic chart would give you a 0.436 BC and likely a pretty low recoil.
I need to stop, or i'm going to talk myself into another barrel.