When I was in the RCN, we did similar training. In basic, we had to use the real injector, although it was filled with saline, of course. During subsequent refresher training, the injectors didn't have syringes in them.
Our "for real" injectors were filled with Atropine - is that the same as epinephrine?
Recruits for all of our military service branches go through them same basic training, so instructors can be from the army, air force or navy. My NBCD instructor during basic had been in the Airborne Regiment, and, after instructing us in the use of the Atropine injector, by injecting into the meaty part of the thigh, said he would then demonstrate "how they do it in the airborne". He then held up an injector - which we subsequently learned had a fake blood capsule inside, but no syringe - and then rammed it into his forehead, followed by a spray of "blood". I'm proud to say, I wasn't one of the recruits who passed out on the floor...