I'm a 5 pin bowler, (the Canadian game!!), bowl 3 times a week in different leagues, and do the mechanical work on the machines at my local alley. Have about a 230 average, (perfect game is 450), but in 5 pin, any game over 300 is very good, so probably equivalent to 250 in 10 pin. Had a 901 triple just the other night, one of my best ever!
Perfect games are much rarer than in 10 pin, so easy to punch the damn headpin!!