I am always recommending subq T injections with #29 1/2" 0.5ml syringes, not 1.0 ml. Why? - because the larger capacity has a wider piston that lowers injection pressure and makes injections slow. - not that I had tried.
The other day I tried a #28 1/2" 1.0ml
#28 vs #29 should flow a bit better.
Loading the syringe takes the same time as the pressure to load is determined gauge, needle length, barometric pressure and the flow opposing vapor pressure of the 0.9% benzyl alcohol in the T. You see that vapor pressure as the T boiling in the syringe.
The suction acting on the larger 1.0ml syringe means that you have to hold the plunger for a long time.
Injecting was really difficult and low. My advice to avoid 1.0ml syringes has been on target. And my arthritis in my thumbs is a factor too.