A lot of perfectly good rifles were marked DP (DRILL PURPOSES) simply because they needed drill rifles at that time and all they had on hand were combat rifles.
Drill rifles were maintained to a lower standard. Bolts tended to remain with actions, but boltheads might be changed-out. A firing-pin might get the tip chipped and still be usable.... as a drill rifle. The muzzle might get a bash which would require work; it didn't matter if the rifle was a DP.
But when 'push' came to 'shove', lots and lots of DP rifles were sent to the Armourers and put back into combat condition and used and used and used.
The problem was that the problem (if any: remember, lots were DP'd just because they wanted drill rifles, especially after the FAL came in) might be fixed, but that marking didn't just wipe off.
An example: I shoot a DP rifle regularly. It was built in 1907, rebuilt in 1924, DP's likely during War Two and scrapped in the 1950s. I bought it in 1965, rebuilt it and I have been shooting it ever since, albeit no longer with Service loads out of respect for its age.
By the time the Number 4 was in universal Service, a new set of markings had come in, the Z series. The worst of these was ZF, PAINTED in letters an inch and a half to 2 inches high, on the butt. THIS marking is a death sentence for the rifle; it means that the rifle has a problem which cannot be cured short of FACTORY level. That usually means cannibalisation of the rifle and destruction of the Body (receiver) and other damaged parts.
But a simple DP does NOT mean that the rifle is junk, even though it CAN mean that.
Mainly, it means "Check carefully before attempting to shoot".
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