I will share what worked for me in the past. I caught my hens at night as mine were more calm when a light was in their eyes. I purchased one of those elastic band head lamps with the red LED light (my hands are free this way). I guess this reminded the birds of a heat lamp light, but it was and is always easier for me to go into their pens at night with the red LED light as opposed to a white light. My Jumbo Ring-necks are the only birds that didn't have any problems bleeding when I put these in. I no longer use these as I increased the pen size plus I decreased the amount of birds I have.
Before I caught my birds, I put one pin through one end of the blinder. Only after I caught my birds would I proceed. Secure the bird, pin through one hole of the blinder, then gently push through the nostril and be careful not to angle. The bird will flinch or mine always did which may be what caused your hen to bleed. After the pin is through the birds nostrils, slowly push the pin through the hole. I always took extra care as I didn't want to hurt any of them.
If you look below you will see a noticeable size difference in the two hens. I no longer have Chinese Ring-necks, rather Jumbo and only a few of them. The Chinese are more wild as you can see when I came into the pen on this particular night they began to scurry whereas the Jumbo hen just sat there. They are more tame IMO and I prefer them.
I don't like the peepers by the way, but they work to stop pecking etc...
I used to have Chinese Ring-necks as well, and they are smaller birds especially the hens. I had to order smaller nylon pins for them.
Chinese Ring-neck Hen
Jumbo Hen
