I bought this as one of the first upgrades for my gun. I immediately noticed a difference in the weight and accuracy of the gun. I noticed a little shred of delrin on the inside of the bolt sort of hanging by a thread, so I pulled it out no problem. I used my friends D.A.R.T. bolt, and it was a little lighter, but I didn't notice any change in performance.
A great upgrade for the money, lightens the gun & improves accuracy and speed. No complaints here