It STARTED as a commercial BSA-made SMLE Mark III*. These were identical to the military model but made strictly for the commercial market and thus fitted and finished, generally, to a very high standard.
It was then reworked by A.G. Parker, who applied his BALL BURNISHED marking over top of the BSA marking, NOT the other way around.
Ball Burnishing was done after a barrel was fitted and finished. It consisted of forcing a specially-made, very precise, super-hard, lubricated steel ball down the bore of the rifle. This smoothed-out any and all irregularities, tool-marks and such from the tops of the Lands. From what I have seen of Ball-burnished barrels, I have a sneaking suspicion that they also id some diamond-lapping on the things, for they were/are marvellously smooth.
For long-range DCRA competitions, you generally figured 300 rounds of Mark VII Ball ammo, the hot, Cordite stuff, before a barrel was lapped-in enough that you could get the best accuracy out of it. PROBLEM was that this also ate into your Leade and that ran your accuracy downhill. This disappeared with a Ball-burnished barrel and you could shoot them in competitions with only a dozen rounds through them. I have seen a number of "possibles" shot at 800 and 900 yards with brand-new Ball-burnished barrels. They were really the Cat's Meow.
Interesting that in the early 1960s you could pick up a surplus SMLE for as little as $8.50 (I still have one), with fairly decent ones going for $12 and very shootable as-is, right out of the barrel or the open crate on the floor. BSA was still producing the very last commercial rifles, or had, only a few years before, and Parkers' could get $100 for a tuned rifle. If you wanted just the Ball-burnished barrel for your rifle, Parkers' would sell you that, too, but it would set you back $60. I was working fulltime in a bakery and making $28 a week, gross pay, with taxes coming out of that, so that wonderful barrel was worth 2 weeks-plus of my pay, or a week and a half for a journeyman Carpenter, nearly a week for a guy working the rigs in 40 below, soaking-wet with salt-water and half-deaf from the Jimmies. But anyone who shot one would swear by it, make no mistake. Likely they were some of the finest, most accurate .303" barrels ever made, anywhere.
Be very careful with this rifle. I you take it apart, likely you will find strips of thin CORK inside the fore-end, taking up space and correcting the bedding to closest tolerances. As well, it is possible that the Reinforce at the Nose Cap may have been cut back to 1 inch from the specified 2 inches; some rifles shot better like that. And it is even possile that the stock might have had the Reinforce cut back to 1 inch and then RESTORED to 2 inches with Cork stripping! ANYTHING is possible when dealing with a former Match rifle.
One point: if your screws are done up tight in the prescribed manner and the thing will not shoot under 2 inches (and likely closer to a half-inch with that barrel)...... or it if shoots erratically, all over the place, then it is likely that the woodwork has developed The Damned Crack. It is at the BACK END of the Forestock, just where the Sear goes down through the wood to make contact with the Trigger. IF it develops The Damned Crack, you degrease, glue with a GOOD 2-part non-shrinking epoxy, clamp lightly for 24 hours, trim and reassemble the rifle, head for the range.
Whoever owned this rifle originally was dead SERIOUS about shooting the best targets possible. Without doubt, they would have been a DCRA shooter. If this rifle won any serious Matches, the DCRA still should have a record if it by number and owner. Well worth checking out, I would think.
A truly FINE Toy!