If your making 5/16" your forming around a .313" metal rod. Anneal and wrap around , then clamp tabs in vice and hammer an over sized metal rod (.324" thru the newly formed pipe. Open the vice, that pipe will NEVER separate/come apart. Tabs will be stuck next to each other for life. For 3/8" pipes anneal and form around .375 metal rod, then push/hammer a .391 metal rod thru , it will be stuck together for life. Where do you live, any where close to Kempton PA? I give a demonstration/talk ever year on making pipes and nose caps. Yes, I agree there is no comparison between "production "pipes and hand made ones. Hand made ones filed up nice add lots of positive vibes to the gun. I like the holding tabs together and heating to a dull red idea, I'll have to try that. Steve