I have had Deca as high as 400mg/ml and not be to thick. I know it will go higher so its not a matter of holding, its just how thick you want the oil, and how much of a bite you can handle.

It'll get mixed with test in the syringe. I draw with a 20G.

My test enan at ~500mg/mL isn't too thick. Not sure if thickness is more of a concern with nandrolone deca.

Gosh, I don't know why I didn't make that test enan at 600mg/mL. Maybe I read that it can crash at 600mg/mL or something.

what kind of pain factor is your 500mg/ml enan? And are you using more than 20% BB?

I guess i am really just wondering, besides plain curiousity, why you would need those high concentrations. Less volumous injects?

0% BB
<=2% BA

400mg/mL testosterone enanthate hurt. But then I mixed it with nandrolone deca and I have little or no pain.

I'm finishing up the 400mg/mL testosterone, but I did do a test injection of the 500mg/mL testosterone enan combined with nandrolone deca and again, little or no pain.

I should mention that the nandrolone deca is only like 230-240mg/mL. I only made up 13g of it, and my smallest beaker is 600mL, which makes it difficult to make small batches. Next time I order supplies, I'll buy a 50mL beaker.

I desire higher concentrations because it allows me to get more gear into a 3mL syringe. When mixing two things together at say 1/2 and 1/2, it essentially halves the mg/mL concentration of each hormone. That is nice in that it reduces pain, but halving 400mg/mL to 200mg/mL is a bit excessive as 300mg/mL probably won't give much pain.

At first, I wasn't so crazy about concentrating the gear too much, but I've come around to see things differently.

I've done this as well.