For a side by side ,choppres are certainly the strongest and with modern production methods on prodution guns I can not see that there sould be any difference in cost .The tubes themself will cost more to produce but this would be compensated for in the,reduction of cost in the assembly,due the the methods used, Cheap Spanish guns are good example . This is not to be confused with hand build barrels for high grade guns . As far as O/U's go ,using a mono block that can be precsision cast will cut machining time down thus reducing the overall cost to the customer. Up untill now there has been very little trouble with mono block barrels ,considering the number that have been produced.They are also expected to stand up to much heavier loads and to more prolonged useage than guns of an earlier generation .But then again manufactureres are not expecting these guns to last for a century.It is not in there interest to do so.
