Back in the '70's I was a serious BR competitor. Most people used barrels from Hart or Shilen with the occasional barrel from MacMillan. These brands were button rifled and hand lapped and were, consequently, very smooth. It was rare when one of these barrels had any real fouling problems and nobody broke in anything.
The first time I heard of anyone breaking in barrels was from a Portland, Oregon shooter who was using Bob Sherer barrels. Sherer barrels were a very well made cut rifled barrel which did not appear to have been lapped. This shooter (I think his name was Bill Simpson)told of shooting and cleaning for ten shots then shooting two etc. etc. Soom users of Atkinson barrels (also cut)adopted similar break-in procedures and soon, everyone was breaking in everything.
Just as superstitious as any other competitive shooter, I started using a modified break-in procedure as well. I simply wiped the bore after the first shot and, if metal fouling was present, scrubbed it out and fired again. If no metal showed I jst kept shooting and inspecting until it did or until my normal number of shots was fired (usually seven or eight). The I just went ahead as usual.
Now, if barrels are not lapped, I lap them. I still inspect for the first few shots but that is the extent of my break-in procedure. Since I can no longer see anything closer than about five feet, it's questionable whether or not my inspection is of any value!
I think it is of as much value to just shoot and clean when groups start to open up.
On moly,
I recently set back and rechambered a barrel which had been shot quite a bit with moly coated bullets. I used uncoated bullets and the barrel shot very well for about 50 shots (about 1/4 moa) then suddenly went sour and started shooting 1/2 minute or worse. This situation persisted for about another forty rounds during which I cleaned often and it is now shooting well again. I assume this was the time during which the moly was half there with patches of moly and not-moly throughout the bore. Nothing to do with breaking in but I found it interesting (and frusterating since the bad shooting phase started about two thirds of the way through a match). GD
