You'll be alright, I use 29g/ 1/2inch myself for test cyp. I draw with 20g pin, and backload into 29g. As far as 1/2 inch for depth, I hit my quad, and I make sure it's dimpled as well, taking my time when I'm injecting. I've been pinning like this for past three years once a week with no problems, and occasionally hit my shoulders as well.
Twice in my life I've had a bad reaction to a pin, redness and swelling, but it was because of a bad batch, and it went away in under a week. There's lots of Bro Science when it comes to gear, and even after three years of me using a insulin pin, I still have friends that swear it doesn't work " you have to be at least 2inchs into the muscle for it to work" .
As long as it's in the muscle it'll work, 1/2 inch, or three inches doesn't make a difference. If by chance you don't go deep enough,(not dimpling) or you shoot to fast (forcing the test back up around the pin) you'll know it ! This is called "skinning" the shot, where the test ends up between the skin, and the muscle, it hurts like hell. You end up with a bump, right where you shot it can hurt, and be sore to the touch for weeks.
I only did this once, and I was really new to the pin, just by reading this post you know more than I did back than. Lots of guys here shoot test with a small pin, Google "Slin pin" here, and you should learn lots. There is a steroid form here with lots of good info, hope this helps