Drawing up with one needle and injecting with another

On the subject in the title: Drawing up with one needle and injecting with another Working notes rather than a conclusion.

A question about technique rather than about dose.

I have been doing the same thing for 4 months and it works, and then I read one of the documentation pages here and realised I may have been reasoning from a misunderstanding the whole time. Nothing has gone wrong; I would just like to understand why it has not.

What I do, exactly, is described below. Please tell me which parts are load-bearing and which are superstition.

Everything in the opening post holds. The case it does not cover is the one I have.

The single most common technique error described here is drawing to the wrong graduation because the barrel was read at an angle. Read it straight on, at eye level, every time.

The disagreement above is smaller than it looks once the terms are fixed.

Needle length matters less than angle for subcutaneous delivery in most people. A short needle at ninety degrees and a longer one at forty-five put the material in roughly the same place.

Injecting into an area that has become firm: lipohypertrophy — thickened fatty tissue from repeated injection in one area — changes local tissue absorption. Avoid injecting into areas that are noticeably firm or lumpy and allow those areas to recover for at least a few months.

Leaving the needle in for a couple of seconds after depressing the plunger reduces leakage at the site. It costs nothing and it is the fix for the "some came back out" question.

I read post #4 twice before replying, because I had assumed the opposite.

Injecting slowly is worth doing for volume rather than for chemistry. Larger volumes delivered quickly are the ones people report as uncomfortable.

The conclusion is tentative; the arithmetic underneath it is not.