T Nation

Backfilling Insulin Syringes


I would have posted this in the TRT forum, but its been dead lately so I thought I might get a better response here.

I started TRT (T-cyp) last weekend and have done two injections so far. I am backfilling a 30 gauge, 1/2" inch (50 iu tick marks) insulin syringe from another needle with a 3 mL barrel.

I can transfer the oil from the bigger one to the smaller one no problem, but by the time I get the plunger in and the air bubble out the tip, I have lost a lot of my product.

For example last night, I squirted 30 iu into the insulin syringe, but by the time I was injecting, the tip of the plunger was down to like the 23-24 iu mark, so I lost quite a bit...it seemed to just continuously drip out...

I don't think this is due to pressure "compressing" the liquid or expanding the size of the syringe, so what gives? Am I doing something completely wrong?


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Thanks for the reply buddy...I figured it was just me being sloppy and impatient with it...I was excited to get it in there! haha

Since I am going to be taking such a small amount (0.15 mL on M/W and 0.2 mL on F) from here on out, would it be possible to just load the insulin pin directly from the vial? Or is the needle just too small to even fool around with?

A few more general injection questions have popped into my head if anyone wants to help a brotha out:

  1. Do you still need to aspirate with an insulin syringe? (I imagine yes)
  2. If so, any tips on aspirating when you are doing a deltoid injection since your other hand is compromised?
  3. A day later, I still have a slight twinge in my delt around the injection--it doesnt appear to be infected. Is this somewhat common?
  4. When backfilling, do you put the plunger back in immediately, or can you just put that cap that covered the plunger on and keep it air tight and sanitary (and just put the plunger in when you're ready to inject)? This would save space when packing multiple needles for travel.



Obviously, the more viscous the oil is, the easier it will flow, so in regards to what BBB was saying how it's a pain in the balls to get the air bubble to float to the needle, heat the oil up first.

Once I 'inject' the oil from the 3ml syringe into the slin pin, I stick the slin pin plunger back into the barrel at a very slight angle (and obviously, it'll only slide in about 1-2mm with it at an angle) but I feel that this allows a tiny bit more air out as you create a seal with the plunger. Once it's in a tiny bit (and the plunger has created a seal) hold the syringe horizontal and slowly tilt it so that the needle points up and wait for the oil to fall, then push the rest of the air out.

That's the way I do it and it's worked so far. A few more times worth of practice and you'll likely be able to do it without even getting any oil on the needle, let alone losing gear.

As for aspirating, if you're one of the people who do aspirate, then yeah go ahead and aspirate with a slin pin, too.

As for delt injections:

Say you want to shoot into your left delt:

Kneel in front of your bathroom sink/counter and rest your left arm on it so that it's resting 'across' your body (but on the counter)...

Then, take your right hand (with the syringe) and drape it over your left arm... your hand should be pretty close to your delt at this point, and in a comfortable position to inject.

I hope I explained that right, lol.

And aspirating with one hand is easy, especially with a slin pin... hold the barell between your thumb and ring finger, then take your pointer finger and middle finger and use those to pull the plunger up.


You can load directly, but it will take a while.

  1. Yes.

  2. I hold the barrel of the syringe with my pinkey and ring finger, and the middle finger goes on top of the barrel flange. The index finger and thumb work the plunger.

  3. I got nothing.

  4. I'm pretty sure the cap just keeps the plunger from getting banged up in shipping. To keep things sterile you need to put the plunger back in right after filling.


  1. aspiration is overrated once you know your body and where your veins are. But you can do it to be safe.
  2. Do a delt injection like this. Rest your injection side elbow on a high counter-top or tall chair. Now the medial delt should be close to parallel with the floor. You should be able to maneuver the syringe much easier this way.
  3. I wouldnt be surprised if this stops happening if you prop your arm up while injecting. I think its a good idea to take all the weight off any muscle receving an injection.
  4. I dont know what the cap youre referring to is. But I do it the same way BBB does. I think the easiest think to do would be to bring a bunch of insulin syringes in their wrappers and bring a 3ml syring filled with the T. Then do the transfer when necessary.

As far as drawing .15ml with a slin pin goes. It's possible. You just have to be patient. Id probably just fill up the slin pin with 3 doses and use it 3 times.


Always have filled directly. I insert into the vial, pull back the plunger and suspend the vial and syringe and come back in a few minutes after filling hCG syringe etc. Back filling sounds like a great avenue for contamination.

Vac pressure is controlled by vapor pressure of BA alcohol. So fill rate is slower because of that. With 50iu syringes, the small plunger can develop around 200 PSI and injection rates are good. If using a 1000iu syringe, pressure will be 1/2 that of 20iu.

29 0.5" 50iu [0.5ml(cc)] works well


Thanks everybody for the responses....this is the cap that I was talking about, but Ether is probably right and its just there to protect the plunger from damage...it doesnt appear to be air tight...

FTR, I loaded the insulin pin directly from the vial tonight (15 iu)...it didn't take hardly any time at all...it was actually faster than trying to transfer from the larger pin to the slin pin...this is definitely the way I'm going to do it for my HRT doses from now on...you guys that are injecting a bit more gear than I am may have a bit longer wait with this method lol


also forgot to mention that I think the oils play a big role in whether or not you can load directly with the slin pin...obviously mine is human grade pharma gear (t-cyp)...I imagine if a UGL used a thicker oil, or different compounds, the results would be quite different...so maybe this really does belong back in the TRT section now!


Backfilling has one big advantage- the pin remains sharp. I backfill when mixing peptides, and the difference is very noticeable. Going once through the rubbertop is the equivalent of using the pin 10-15 times, at least.


I have had US compounding pharmacies deliver Test Cyp so thick I could barely draw it through a 25ga needle, and UG labs have delivered gear that flowed like water. Sometimes it is better to buy a product that is used by the person who sells it.


So a question: if you fill directly from the vial with the slin pin, is it still advisable that you can do an IV injection (gH). I personally don't like the idea of that, OR of losing product from backfill leakage when there's not much of it to go around...but if it's still kosher, then whatever.

Personally I don't know if I could do an IV inject.


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Nice tips in this thread. Another possible option is to draw with the "regular gauges", and then use 27G 0.5" needles. Not that much bigger than slin pins, yet you get fresh needles for injections, and easy draw.

I didn't know gH was injected IV. Really? What about peptides (such as GHRP2/6): better IM or subQ?


It was a BBB idea, as far as I know I have known no other people to experiment with it. Personally I don't know that I could do it lol. And I know BBB doesn't recommend it because he doesn't want to be responsible for some fuckhead doing something retarded. I certainly wouldn't want that!!


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I have started loading the insulin pins directly from the vial and they are plenty sharp enough to penetrate the skin when I do my injection...

In fact, the other day I buggered up the withdrawal from the vial and had to reinsert into the vial a couple times, and the 30 gauge 0.5" slin pins that I have had no trouble with a deltoid injection...I really just don't see the benefit of complicating things...the slin pins load quickly (for TRT doses, but really shouldn't be much longer for higher doses since mine only took about 30 seconds)...and shoot quickly as well, with no trouble in skin penetration...


And after I reread my post in its quoted entirety, I realize you guys are talking about injecting GH intravenously...so at no point in my rambling response did I even approach a coherent answer to the topic at hand....my bad!


Fisting or fingering? Ah ah I don't think I'll forget the analogy, so it's a good one :slightly_smiling:

I have not used GHRPs yet but definitely plan to, and very soon too. For the occasional time the GHRP shot comes with a AAS one, can we mix them both in the same needle? Or it's a bad idea to mix oil based AAS and water based peptides?


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