25 gauge nearly as thin as a slin pin?
or do you mean the syringe which contains the oil?
the smaller the syringe is (less diameter) the more pressure it creates
thats why slin pins are so easy to inject with, even if the oil is thick as hell
try injecting with a 10ml syringe body, you wont get any oil into yourself because the diameter is huge, even 2ml vs 3ml makes a big difference
quads are my go-to spot and i only inject them with 27Gs and theyre scarred already
sometimes i cant even get the oil in without pushing hard, which resulted in the needle slipping off from the pin (luer slip) and the oil blasting all over my leg