No.5 Mk1, "D" mark on knox form, is this "DRILL ONLY"?

Hi group,
I acquired a sporterised No.5, (F) B5XXX, 10/44. The rifle has a capital "D" inside a circle stamped on the top of the knox form. Nowhere else. Action, barrel & bolt serials all match, and all are broad arrow stamped. There are 3 partial stamps on the knox; they look like "3" or badly done Longbranch "LB" stamps.
Does anyone know the significance of this?
Is this the dreaded "Drill Purpose Only" rendering the rifle unsafe or unsuitable to fiire?

The rifle has been drilled & tapped forward of the action for a scope.
This, and the broad arrows lead me to conclude that it was at one time fired.
Any help will be appreciated.
Thanks.
Gord P

Skennerton's "Broad Arrow" indicates that mark as a draw lapped barrel.

Thank you very much, Brian.

Not meaning to be contrary or facetious to Brian and others who think the same, the Armourers book of markings in EMER V- something or other says that this D in a circle indicates to Armourers and others that really need to know these things in service, (as opposed to the obvious question '...... who cares whether it's draw lapped or not.....) that '........ in order to eliminate waste during production, the extraneous barrel machinings have been indexed to the breeching up thread as opposed to the more complicated task of indexing the thread following certain machining operations......' and on and on as EMER's are want to do.

So, in short, depending on whose view you take, the rifle isn't a DP (I never ever saw a DP No5 in my service) and the D in a circle indicates to Armourers (that need to know these things of course) that the barrel should index more easily when breeching-up

But I could be wrong.................

Peter, a couple of years ago, I asked you about the D in a circle that is stamped on one of my No. 8s. Which immediately eliminates the Drill Purpose idea. Whatever the answer, it should be valid for a No. 5 AND a No. 8. At the time, you wrote that draw-lapped did not seem a plausible explanation for a No. 8 barrel, so the indexing explanation is all that remains - for the moment.

:wave:
Patrick

I'll elaborate that Skennerton's "Broad Arrow" book states that marking for the SMLE which the No.5 certainly isn't. I'd definitely go with Peter's view on this one. Having breeched up a few, I'd sure like to see it more often!! Easier is ALWAYS better.

This question arises about every year or so. As far as I can make out, it's a Faz marking indicator unless anyones seen it on a BSA made No5 or 8. Not that it matters much

Pending further info from Peter, I have concluded that the D on my No. 8 stands for "Diabolically accurate".;)