Re: Hi Power shooters using XL-550 or 1050 Super
I am using the Whidden tool head on a 550 for exactly what you describe, 77gr 5.56.
Run-out is significantly better than with factory part; avg .002 with Dillon dies and good brass prep ( I send @2500 cases at a time down to this fellow in TX, "Custom brass processing", I think, he does everything except uniform primer pockets). I do the primer pockets, sort, and load and the results are excellent. Have another Whidden tool head which will go for .308 on another 550, I've just been too lazy to change the dies out and haven't needed to re-load .308 yet. Don't know exactly how he does what he does but everything John Whidden makes is truly excellent -- also use his bullet-pointing dies on 6mm and 6.5 with great results. You will like the results.
Best,
James