When I was developing loads for my .223 NEF, I decided on using Hornaday and Nosler 55gr bullets. I chose these bullets because I hunt coyotes and I like the heavier weights. I use only Benchmark powder now. When loading/shooting the 55gr Horns (SP's), the OAL is 2.300. My best group, in my 60 yard range (backyard) was .250. When loading/shooting the 55gr Noslers (BT's), the OAL is 2.335. My best group with these Noslers was .187.
I have shot other brand 55gr bullets in my NEF and they all shoot very well.