"docn8as: I'd like to hear more details on the aluminum collar application. Does each collar conform to the taper of the barrel and then need the OD turned for the steady? How do you get the barrel and collar concentric? Sounds tricky."
actually pretty simple ......if used for final contouring & finishing a blank , just put a tailstock center in the small end of the barrel .....chamber end is held on center by the dog lashed to the faceplate ( you SHUD cut new centrs in the blank as they are USUSALLY wallowed out ).......aluminum split clamp has been bored to the taper , if there , & clamped to barrel
clamp is then trued up & stdy rest clamped on it ...T/STOCK IS MOVED AWAY ...if one is reall picky , you can make centered barrel plugs for both ends , but in another life 45 yrs ago i made more than a couple match winning barrels w/out A breech centered barrel plug ...when crowning or recrowning , i DID use a centered barrel plug in the t/stock when trueing up the split clamp ..w/ the lite cuts used in crowning , a center in the spindle is ususlly adequate for the chamber end .....again barrel is held by a lashed dog to the faceplate
collets & 3 & 4 jaws have been used to hold the breech end , but 4 jaws take more time & 3 jaws /collets/ particularly imports do not have the accuracy of "on centers".....in fact nothing really does if your t/stock is dialed in hor/vert for the particular length ......
after awhile you have several diffierent tapered clamps which will work on near all barrels & on MATCH barrels w/ out taper a staraight bore is even easier ......to get the taper , just dial in the compound indicating on the barrels taper
FWIW ...you can also turn a shoulder on the split clamp & set the stdy in fornt of the shoulder to keep the barrel on the rear center ..........but a rawhide shoe lace ties the dog to the plate pretty quickly ..........
FWIW 2 if you are working from rough blanks , the one in belt sander I welded up way back slips off teh bench mount & mounts on the tool post .....no more DRAW filing , & no more "hills /valleys when sighting down the barel
best wishes
doc
