ORIGINAL: brucelanthier
You can also get 50 and 100 grain brass inserts from 3rivers. Be careful getting the PDP weights as some have a diameter that is bigger than the inside of a carbon shaft. Those are for aluminum.
I have no problem putting them inside my Gold Tip XT's so I believe they will fit inside any normal diameter shaft. Not so sure about the narrow axis type shafts though. But the brassinserts are a good way to go too.