barrel end adapter

Can somebody quote me a charge to fabricate a barrel adapter? I am not a machinest. Hopefully my description will make sense.

One end would slip over the muzzle – must be pretty close tolerance – with a couple grub screws to lock in place. The other end would be threaded to standard, ie 1/2 x 28. the threads need to be concentric to the bore, which is why the barrel end needs to be pretty close tolerance so whole thing can be kept straight and concentric w/ the bore. I am not sure long the threads need to be – maybe 1/2 inch? The adapter needs to bear an actual weight of about 5 ounces. about 3-4 inches out from the adapter. With safety margin – say 3-5 pounds with less than .015″ deflection at 5 inches? I am guessing on the deflection. I think deflection will have alot to do with how far the adapter slides onto the barrel.

Not sure how much runout I can tolerate. I figure I need to keep it within .01″ at 5 inches.

In terms of materials – can aluminum take this thread ? Think aluminum would be the material of choice from weight point of view.

I have more than 1 barrel – they seem to be pretty darn close in diameter. My intent would be to be able to use the same adapter on any of my 3 barrels. Has anyone seen enough of these barrels to know if they keep the diameter pretty constant? Mine seem to be .625″ or 5/8 inch.

I have no honest idea how much work something ike this would be –