I have three 31's now. A large black micarta, large natural micarta, both birthed the same day (March-ish), and a large PJ that was birthed in June. They all have varying degrees of flex. Which doesn't bother me, anymore. The natural is the easiest to flex, but has the best action of the three. The black has a small amount of flex, and a more stiff action. The PJ has almost zero, and has stiffer action, but is still new and breaking in. They have been disassembled multiple times each. I have had no issues with side to side play. Or screws backing out with use. They are more finicky to assemble right, which I dislike. I have three 21's, and they assemble the same every time. The 31 should be the same.