For larger pre-loads, I like these syringe cases. They are not much bigger than the syringe and keep it from accidentally injecting.
Available on Amazon:
https://www.amazon.com/Medicool-Wright-Pre-Filled-Syringe-Case/dp/B000VBDXT8/ref=sr_1_1_a_it?ie=UTF8&qid=1537461865&sr=8-1&keywords=syringe%2Bcase%2Bwright&th=1