When you say metallic artillery do you mean fixed charges as you just put in the gun without touching the charge? If so there was a 1 inch (I believe) round that appeared in the late 1800s and was adopted in the US. Tanks using the 75, 90, and 105mm round are fixed charge rounds.
There are no fixed charge artillery rounds in use by the US or anybody else I know (but I could be wrong). 105mm howitzers are a semi-fixed round you pull apart to vary the powder charge. 155mm is and always has been separate loading, ram in the round and then put in the powder bag. 175mm guns and 8" howitzers are also separate loading.