I do this frequently and use a 10ml syringe with needle regardless if either bottle has a restrictor. Fast, easy, and zero wastage. If it is easier, depending on the shape of the plastic bottle, then you can empty the plastic bottle into a clean drinking glass, and repeatedly fill the syringe from there to transfer to the glass bottle.
A while back, I bought a 50cc food-grade syringe on eBay (maybe 15 years ago...). I usually use a clean glass to pour the AS in. I then pull the AS in the syringe. Finally, I push the plunger in the recipient (very well-washed Tabasco bottle - 57ml format - in my case).
The syringe has a built-in plastic tip which makes it easy to use with a restrictor. For some bottles, I can plug the syringe directly, turn the bottle upside down and charge it. But not all bottles work that way. That's why I use a small drinking glass as the middleman.