Hcg is typically injected sub q with insulin pins, but it's ok to inject IM but the Human Chorionic Gonadotropin (HCG) will metabolize a little faster IM. The thing is, Human Chorionic Gonadotropin (HCG) becomes harder to measure in a 3ml barrel unless your adding ridiculous amounts of bac water to it.
I don't know I only inject it with insulin pins.
Also a 25g is perfectly fine for any oil. That's actually the largest I use these days. After almost a decade, I'm trying to minimize scar tissue and actually only use 25 if I need more than 1ml at a time.
I inject all oils with a 29g slin pin in delts. I don't heat the oil at all and it moves thru it just fine and scar tissue is no longer a concern even with ED injects. Pluse they work great for pecs, traps, bi's, tri's. There are a lot of good spots but I actually don't do bi's anymore because it was becoming painful and I can't reach the plunger to hit tri's. Ventro Glute is a nice spot for 3ml.
Anyway you are fine injecting Human Chorionic Gonadotropin (HCG) with your test but dosing will be less accurate in a 3ml barrel due to the size. I add 2ml bac water to 5000iu Human Chorionic Gonadotropin (HCG) so each 10mark is 250iu and pretty accurately measured in a slin pin. but you have to think that's only 1/10 ml. In a 3ml syringe, this will be difficult to measure accurately due to size and shape of the rubber inside the plunger. I would keep it simple and use a slin pin for hcg.