Let's start at the beginning (ground zero)...
There were 29 control rounds which formed part and parcel of exhibit DRH/22. Each round should have been given its own unique Lab' item number, so let's for arguments sake lay everything out here threadbare, and say the following exhibit reference system should have been adopted:-
The batch of control ammunition consisting 29 separate rounds, here goes...
(1) - DRH/22 (1)
(2) - DRH/22 (2)
(3) - DRH/22 (3)
(4) - DRH/22 (4)
(5) - DRH/22 (5)
(6) - DRH/22 (6)
(7) - DRH/22 (7)
(8) - DRH/22 (8)
(9) - DRH/22 (9)
(10) - DRH/22 (10)
(11) - DRH/22 (11)
(12) - DRH/22 (12)
(13) - DRH/22 (13)
(14) - DRH/22 (14)
(15) - DRH/22 (15)
(16) - DRH/22 (16)
(17) - DRH/22 (17)
(18) - DRH/22 (18)
(19) - DRH/22 (19)
(20) - DRH/22 (20)
(21) - DRH/22 (21)
(22) - DRH/22 (22)
(23) - DRH/22 (23)
(24) - DRH/22 (24)
(25) - DRH/22 (25)
(26) - DRH/22 (26)
(27) - DRH/22 (27)
(28) - DRH/22 (28)
(29) - DRH/22 (29)
In turn, once test fired in rifle (18), each of the above exhibits would have compromised of two separate parts of each piece of a control round, namely (a) the spent cartridge case, and secondly (b) the bullet, or as you wish, (b) the projectile...
This then would have created the following exhibit references available to each component part (a) or (b), of the DRH/22 basic exhibits (1) - (29), as follows:-
(1) - DRH/22 (1) spent cartridge after test fire (a), bullet/projectile (b)
(2) - DRH/22 (2) spent cartridge after test fire (a), bullet/projectile (b)
(3) - DRH/22 (3) spent cartridge after test fire (a), bullet/projectile (b)
(4) - DRH/22 (4) spent cartridge after test fire (a), bullet/projectile (b)
(5) - DRH/22 (5) spent cartridge after test fire (a), bullet/projectile (b)
(6) - DRH/22 (6) spent cartridge after test fire (a), bullet/projectile (b)
(7) - DRH/22 (7) spent cartridge after test fire (a), bullet/projectile (b)
(8) - DRH/22 (8) spent cartridge after test fire (a), bullet/projectile (b)
(9) - DRH/22 (9) spent cartridge after test fire (a), bullet/projectile (b)
(10) - DRH/22 (10) spent cartridge after test fire (a), bullet/projectile (b)
(11) - DRH/22 (11) spent cartridge after test fire (a), bullet/projectile (b)
(12) - DRH/22 (12) spent cartridge after test fire (a), bullet/projectile (b)
(13) - DRH/22 (13) spent cartridge after test fire (a), bullet/projectile (b)
(14) - DRH/22 (14) spent cartridge after test fire (a), bullet/projectile (b)
(15) - DRH/22 (15) spent cartridge after test fire (a), bullet/projectile (b)
(16) - DRH/22 (16) spent cartridge after test fire (a), bullet/projectile (b)
(17) - DRH/22 (17) spent cartridge after test fire (a), bullet/projectile (b)
(18) - DRH/22 (18) spent cartridge after test fire (a), bullet/projectile (b)
(19) - DRH/22 (19) spent cartridge after test fire (a), bullet/projectile (b)
(20) - DRH/22 (20) spent cartridge after test fire (a), bullet/projectile (b)
(21) - DRH/22 (21) spent cartridge after test fire (a), bullet/projectile (b)
(22) - DRH/22 (22) spent cartridge after test fire (a), bullet/projectile (b)
(23) - DRH/22 (23) spent cartridge after test fire (a), bullet/projectile (b)
(24) - DRH/22 (24) spent cartridge after test fire (a), bullet/projectile (b)
(25) - DRH/22 (25) spent cartridge after test fire (a), bullet/projectile (b)
(26) - DRH/22 (26) spent cartridge after test fire (a), bullet/projectile (b)
(27) - DRH/22 (27) spent cartridge after test fire (a), bullet/projectile (b)
(28) - DRH/22 (28) spent cartridge after test fire (a), bullet/projectile (b)
(29) - DRH/22 (29) spent cartridge after test fire (a), bullet/projectile (b)