Can someone ID these markings?

[ArmedGinger]

I know the C-Arrow but wondering about the rest.

1917 Eddystone

 

[Dosing]

I was thinking 12th armour, but could well be wrong.

 

[jtaylor]

Hello AG. I looked through my books - nothing. However the large numbers as those and the way they are set up with a rack number
underneath it is reminiscent of RCAF marks commonly found on Model 1917 rifles issued to the RCAF. My guess is 12 th training company.