Discharge bag

I have a small Morrel discharge bag. The last couple of years it has worked just fine. This year my bolt blows fletching deep into the bag at 25 yds. The only difference I can think of is that that I stopped using the wax the came with my xbow (Carbon Express Covert SLS) for the rail lubricant and started using actual wet xbow lubricant. This seems to have helped my accuracy ... might it also have increased the speed enough to bury the fletchings in the bag?

What does everyone else use to discharge their xbows?

This is what I've been using, and it's still in really good shape: Morrel Discharge Bag