You could start the bullet by hand and then hit it with a 2X4 also ( PLEASE DO NOT DO IT )
BUT THAT WOULD BE THE WRONG TOOL FOR THE JOB---(correct ? ) Say yes.--good.
Seating dies are made to hold the case neck in close proximity two the bullet being reloaded.
This is to help reduce bullet run out. I think you would be better to hold off for the correct tool for the job, and perhaps kill the time in another way.
Remember consistency in reloading is the key, so what would be gained by loading the way you propose and then doing it again with a different tool ?
Think you can see .003 run out by rolling on a piece of glass ? Try it and then use the proper tool tool,
to test for run out, and see how good you eye is.