55gr Win FMJ will be fine for fast and fun, but they suck for accuracy. 335 works, but I prefer X-T/2230 for 55gr FMJ bullets. If you want an inexpensive yet relatively accurate 55gr FMJ get ya sum Hornady.
For accuracy my AR 1-9 likes Sierra 53gr MK with a variety of powder, X-T/2230, 748, Benchmark and Varget, in that order.
Just starting out loading for your AR ? Read this and always FL size.