I see too many times that people post things about the dumbbell curl and they worry too much about form, keeping elbows close, and not rocking, but they miss the important part of just getting the weight up, with reasonable form. Much the same as Jesus when he spoke about tithing and keeping rules, he warned not to worry too much about tithing and rules but to focus on the important things which are: mercy, justice and faithfulness.
So all that you need to do is take a heavy weight and do your best to get it up with reasonable form. You can swing a bit.
How to do it intended intense