Ray I'm going to need to correct you on this. Cleaning before shooting is always a good thing. But it is not a break in. With a new rifle, especially a production rifle, you need to first clean it and remove any packing preservative and oils. Then do a barrel break in should you desire to do so. It is relatively a time consuming process. My technique is as follows: Clean the bore after each shot for the first 10 shots. Next is to clean the bore every 5th shot for the next 50 - 60 shots. What this does is laps the bore and eliminates the areas were fouling can build up. This results in a smoother bore that is easier to clean.
With a used rifle I usually scrub it real good with a copper solvent then run an oiled patch followed by a rigorous lapping with J-B Compound then another cleaning. This usually results in getting out any copper fouling and smoothing out the bore. I can usually tell after the first range session and during cleaning if it needs some more work .
Is it necessary. For the average shooter - I'd have to say no. But IMO if you're going to hand on to your new rifle for a fairly long time why not do it? But its your $$.