DP = Drill PURPOSE and not Drill practice. Just a minor point.
Our DP rifles were up to the accepted standard except for a few minor points. Springs could be below the accepted weight requirement, the number of wood patches could exceed the allowable number per item (usually 3 on a fore-end or a butt and 2 on a handguard) so long as the strength of the rifle wasn't impaired. And before the barrels were milled across and plugged in the mid/late 70's, the bore had to be reasonably bright but did not need to conform to any gauging limits. Striker protrusion always removed. Usual white banded markings of course