They are a bit on the big side IMO.. I have always used 8mm tip, 1ml, 28-30g insulin rigs.. They work well.. Last time I had the 1 inch tip needles, I didn't like them very much.. they were just too long for my liking, and I missed a few times.. never miss with the short tip, 8mm needles.. but with the 1" needles I tended to puncture through my vein after registering, and it would cause me to miss.. then have to pull the rig out, and find another site to inject into..
SO, if your a novice, or even if you know what your doing those aren't ideal... especially since your a novice though. I would try something a bit shorter, and a bit higher gauge than 25 that's a little big... they will work, but not as well and will be a bit more painful to use, compared to the short tips (8mm is my size I have always used, 0.5 inch will work too), and 28-31 guage needles. Good luck, be very careful. That long tip and thick needle, can do some harm if your aren't... if you haven't begun injecting H, I don't suggest you do.. I cant stop you, obviously just say.. I was an IV opiate addict for years, and now am an IV buprenorphine addict instead.. got off dope for good like 15 mos ago.. but now I am totally addicted to bupe.. I don't know if my needle fixation will ever go away.. but I wish I never started! that's all I can say, it does feel way stronger IV, but with dope, its way more dangerous.. and it doesn't lead anywhere good in the long run..
Sorry, not trying to lecture.. just sharing my experience with shooting dope... not worth it! it feels awesome, but becomes less and less awesome as tolerance builds. Stay safe!