Yeah, I started with 3mL (just what the pharmacy gave me), then was sent 1mL syringes with my T after about 2 years of using 3mL... The 1mL syringes are a lot more accurate for dosing and are easier to inject with.
However, I was able to inject with 3mL without my leg getting sore. But I did have to deliberately inject very, very slowly. It does seem like the plunger is hardly moving, but the liquid is indeed being injected. Trying to push it faster is just asking for a sore leg.