Not from the factory, but the metal band for the larger diameter barrel can be made to work quite well.
Low tech solution is plumbers tape. Wrap the section that fits in the band until it's a snug fit...can still move in and out (which takes care of expansion/'contraction from temperature) but no side to side or up and down play. It's hidden under the band.
Can shim the too large barrel band with strips cut from al. cans. Again, looking for the snug fit, able to pull it in and out, but not wiggle it side-to-side or up-and-down.
I've tried two o-ring solutions. It's a pain in the arse to cut a seat inside the band, but it can be done. Have also tried cutting seats on the barrel. Again, looking for a snug fit as above (not hog-tied so it can't move...but limited to only in-out movement for expansion/contraction).
To tell the truth, can't say that any one of the above is "better" than the other. The tape is low tech, but it seems to work just as well as the more complicated solutions.
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There are two other things that seem to help.
Getting the barrel to be a tight fit to the breech. A good fit is better than 2 set screws (another common modification). that barrel rests on 3 o-rings, but it should be a good decent fit without the o-rings; not wobbly losse like many of them. While it can feel tight with the o-rings in place, you can't rely on flexible o-rings to hold still when 700 to 1200psi (of co2..depending on temperature)is shot through it.
Much better results when the barrel is tight even with the o-rings missing...need the 0-rings for sealing, but can do a trial fit without them.
How to get it tight?
Either plumbers tape, shims, or enlarge the barrel shank. To enlarge it, can polish it to bare steel, "tin" it with silver solder, then work the silver solder back to the barrel just barely enters.
Get that nice and tight, and you might find you doen't need any barrel band at all.
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ANY of the barrel bands work best if they don't slip around the gas tube. Can roughen the inside of the bottom of the barrel band, roughen it's foot print on the bast tube, and epoxy the barrel band to the gas tube.
Or can drill/tap (make it small...like 5/40 ) the metal band for two short set screws, angled down from the middle (thick) sectionto contact the gas tube and hold the band in place.
Or can do BOTH (set scrsw and expoxy).
Still want the barrel to be a slip-fit (able to move in and out, but not side to side or up and down), but with the barrel band not moving on the gas tube, can better handle the small knocks and bumps that always see to come a QBs way.
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Lastly...make damned sure the reciever is firmly on the gas tube, front and rear. Too long a transfer port tends to make the front of the breech rise up...which does nothing for stability. Too short and the damned thing leaks gas. Get it just right, no leaks but the breech firmly and evenly down.
