Look into the compressor also as you're going along, or local places that will fill your cylinders for you. I only had a scuba place and they did not go to the pressure I was wanting as their equipment is set up for a different use. So, I was starting at a lower than ideal pressure from the start. The home compressors have gotten a lot better in recent years which makes me reconsider it some but I have enough stuff. Many years ago my Father, Brother, and I all bought "Big Bore .44's" from one of the Korean companies. I think they still make them, they are .45 actually. Loud, heavy, and bulky. About on par with a 45acp IIRC. I think my Brother has 2 of them now. Someone really wanted mine as they weren't common back when so it went down the road. They can be great fun, just weren't my thing. Same for crossbows, I use one as I have to here, but would much prefer a rifle and a big bore handgun. More range and a more humane kill in my mind with less lost game. Yes, I know people will argue that and question my tracking skills, but its my opinion, nothing more.