How fast you can push the gas check bullets depends on how hard they are. I have pushed some Lead Head bullets to about 2,500 fps. with absolute no leading. The guy I bought them from said he has pushed them to 2,700 fps. with no leading, I believe him. With the weight of bullets I`ve got I should be able to push them to over 3,000 fps. and may just see how fast I can get them befor I start to get leading, but good hard cast gas checked bullets are good hunting bullets, just make sure you have a big flat point on them, Keith style.