The problem may be in the position of thumb hole (where the stock rises from the hand to the comb), rather than in the length of the stock.
If the thumb hole is set too far forward, your hand is going to sit too close to the triggerguard. Pull the trigger, get a bruise.
If the thumb hole is set further back, your hand will be set back from the guard. Pull the trigger, you won't get a bruise.
I'm not sure what the thumb-hole-position length is called, but I know it can make a big difference in how well the gun fits.
Of course, if you have meaty paws and stubby fingers, I'm not sure what you do...
OWD
