Full Length Or Neck Size

[tome]

I did something i said i wasn't going to do..buy an AR15.when new brass is shot thru the same gun, does It have to be fl re sized each time ? can you treat the brass the same way as a bolt gun ie:neck size till the oal grows..then fl re size and trim..do you have to crimp ?

 

[284driver]

Full length size. I bump about 4 thou. And crimping is not necessary on an ar15.

 

[KevinThomas]

Full Length or Small Base size each and every time, and don't ever even THINK about neck sizing brass that's to be used in an AR. That's nothing but a recipe for trouble, and I can assure you, you'll find it with Neck Sized brass. Dittos for skyav8r's comments on bumping the shoulders and crimping. Good neck tension is perfectly fine, and crimping will generally degrade accuracy.