Replying to Can somebody give me advice with backswaps?

So I learned backswaps on PVC this year. However I wanna take this trick onto bigger rails like flat downs/ hand rails or higher rails. However I can't commit and always either don't try and just slide the rail or eat shit hard. One of my problems that I notice when I watch footage of me trying it is I go super slow which works on the low PVC rail but not so good on the taller flat bar or hand rail. So I tried to correct this problem but I find that when I hit the rail fast I got sloppy and catch edge and die or end up coming off the rail. I need help as I want to step up my rail game from throwing 2s out all the time. Inb4 commi harder. I've been trying.