Agree with Chuck that the cheek whacking is more due to pitch, but I do also think that your LOP should be more towards maybe 16". I am 6'1" with 34" sleeves and find 15"LOP adequate.
Here is a clarifying excerpt from Michael Yardley's Gunfitting book:
“The vast majority of guns measure in the range of 12 1/2in. To 16 1/2in. (length to centre) with ninety per cent of men being accommodated in the range 14 to 15 1/2in. The basic rule with length is that the shooter should have as long a gun stock as he can comfortably and consistently mount and swing. A gun with a long stock points better than a gun with a short stock and, providing it is not too long, controls recoil better.”
Better more length than less.
JC(AL)
