PSE also makes the black mamba which includes 10.5 gpi weight tubes.They come with stainless steel inserts and collars. I set some up for a customer a few weeks ago that was going to africa and it seems like they weighed about 600ish grains with out a broadhead. With a 200 - 220grain broadhead you should be able to easily reach 800 grains total weight.

http://pse-archery.com/prod.php?k=56063&sk=56063&u=RXB#