A Korean 4 ball match, using 65mm balls, on a ten foot Soren Sogard table with what I believe is a rail modification for the larger 65mm balls. The match is played by Eddy Leppens of Belgium, and Fredric Caudron. https://youtu.be/-Ap3U4J4y30
Well, but, but, ... The only way those two players are going to average about 6 at straight rail -- and without the corners barred -- is if they mostly want to show that the game is not so easy.
The rules of that particular 4-ball game seem to be straight rail, no balk areas, if your cue ball contacts the opponent's cue ball, it is a foul.
Do tables normally intended for Korean 4 ball indeed have higher rails?
The times I've played in Korean rooms in Dallas I played both 4 ball and 3 cushion, with the appropriate set of balls for each, on the same table and both games felt 'right'.
Though what I don't know about 4 ball could just about fill an ocean.
I recently converted my Korean 4-ball table from the 65.1 ball to our 61.5 ball. I lowered the nose height 3 mm. The 65.1 balls look like baseballs and are much heavier, 7.96 oz to 6.73.