I just wanted to mention I have used a 29 gauge insulin pin for the last 2 weeks. This is how I did it. (I havent read this whole thread, so forgive me if someone already posted this). I also want to say that sucking up test cyp with a 29 guage pin is nearly impossible. I tried!
1) take normal 18-23 gauge syringe and use that to suck up the required amount of test cyp. For me it was 1/2 cc or 100mg.
2) take plunger out of insulin syringe. Mine are 1cc 29 gauge. Be careful where you put the plunger, you dont want to contaminate it!
3) squirt the test cyp from the 18-23 gauge syringe into the back of insulin syringe. You know the place where you took the plunger out of....
4) replace plunger in insulin syringe. You have to be a little careful here because if you push the plunger too hard you will squirt out your test cyp. So put it back and then turn it upside down and then get the air out of insulin syringe.
Now you have a 29 gauge pin with your cyp in it. I inject it straight into my hip(s). It's only mildly painful for me on the next day. But overall I dont notice it. It's just easier for me this way than reaching behind me to inject into my butt. And the last time I injected into my butt, I hit a vein and I ended up with a nice big lump and bruise that bothered me for 2 weeks.