I just bought a ping mb 52degree and a56 degree wedge. The problem is I only hit the 52 degree wedge a few yards farther than the fifty six. If I replace the shaft with one one inch longer will that increase the distance?
You are asking a question that gets into complicated grounds and the answer is pretty much individual. If you lengthen a club, it also gets heavier in terms of swingweight, or relationship of weight distribution from grip to clubhead.
Depending how young and strong you are, you might be able to tolerate the change and swing it faster, the length allowing you to increase clubhead speed, thus hit the ball farther. On the other hand, you might find that the extra weight doesn't allow you to swing as fast and you might actually lose distance.
So, what to do... First, consider whether you want one extra long club in your bag. Probably not a great idea.
I'd check your setup and see if the difference in the length of the two clubs, probably around 3/4", has you setting up just differently enough that you are hitting the PW less distance than you could or whether you are nuking the SW.
Look at this as an opportunity too... If you have stumbled on a SW you can hit as far as a PW and if the gap in distance between that and your 9 iron isn't too bad, you might be able to eliminate one club from your bag and find something more useful like a gap wedge or utility wood.