Assuming you mean the plastic stocks?
Probably someone has, but I doubt you’re going to make a ton of difference. The foam inside the butt weighs next to nothing. Probably the most you could save by doing any one thing would be a couple ounces by exchanging the factory recoil pad for a microcell pad, but that will also change the pitch unless you use an angled spacer. Frankly, I dont think the juice is worth the squeeze. If losing a few oz is that important spend a couple hundred bucks and get one of the stockys carbon stocks, that’ll save you 5oz or so and you could probably save another 2-3oz by replacing that pad with a microcell.