If you are raising the sights to be POI/POA at 15ft, you'll probably be a foot high at 30yds.
You are not considering that the line of sight through the sights are ~3/4" above the axis of the bore. At this very close distance, you are causing the flight of the bullet to cross the line of sight very close to the muzzle, hence the trajectory of the bullet is rising in relation to the line of sight so close to the muzzle.
I suggest you set your sight for 50ft rather than 15ft. This will give you something like a 50-60yd zero, with bullet being about 1inch above the line of sight at 25-30yds, and about 5-6 inches low at 100yds.
A Ruger 10/22 w/stainless/laminated stock I had back in the early '90's came from the factory with sights dead on at 50'. The original factory barrel was somewhat more accurate than the bull barrel I fitted it with later. I eventually sold the after market barrel/stock combo and remounted the original barrel and stock. A friend wanted more than I needed it, and he still has it. With clean magazines and good ammo, it is and always has been 100% reliable and 3/4" accurate at 50yds.
RE: Remington 597
I've got two. One is a .22winmag. Both wear a Boyds gray laminate stock I bought on sale a number of years back. Both have been glass bedded and free-floated in the barrel area. Both have had trigger jobs to include an over-travel screw mounted in the rear of the trigger guard.
Both are very accurate. .22mag is MOA at 100yds with capable ammo with no-wind conditions. The .22lr is 1/2" at 50yds with capable ammo. Both are fitted with Weaver base and 1" 3x-9x scopes with target turrets and Adj.Obj.
The .22mag has been very reliable feeding with all ammo except the discontinued Federal 50gr Gold-Dot hollow points (bullets "hanging" on feed ramp) and Winchester "Dyna-Points" due to marginal recoil from reduced power ammo. Though if rifle is kept "very, very clean", the Dyna-Points are more or less reliable.
The .22lr is a bit more problematic. The magazines I have are the later designs and more or less are reliable with "good" ammo, but if left loaded for extended period will "fail to feed" on the first 2-3rds of a full 10rd load. Solution is to only load 7rds.
I have a 30rd Remington branded high-cap magazine. With good ammo (CCI Mini-Mags) it is reliable. With the Federal Bulk pack copper-plated 36gr it will give occasional failure to feed.
These are decent rifles, and IMO more accurate than "out-of-the-box" Rugers, but they are still often "problematic" until tweaked, tuned, and/or modified......
Give your Ruger a little time, and give youself time to learn more about it, before you give up on the Ruger.
The Remingtons and Rugers are 6 of one, Half Dozen of the other.....