I don't crimp any rifle ammo, except for my .444 Marlin shot shells.
I might decide to do so with something like .375 H&H or .375 Ruger, and up; but my cartridges (.223 Rem to .35 Whelen/.444 Marlin) don't really need it.
I have used factory crimp dies on a few cartridges, and consider them to be a gimmick to sell dies (rifle), or a bandaid to cover for bad reloading tools or technique (pistol).
I crimp my .308 loads with the lee factory crimp die. Lee claims it will increase accuracy and I have no reason to doubt it... Ive never actualy seen a post where someone says they have tried it and it didnt help with accuracy, though there are plenty of people who have NOT tried it that diss the FCD......
The test will be performed with 140 gr Nosler Partitions in .270 Winchester, being shot out of a Ruger M77 Mk II Sporter (SS/Laminate) topped with a Leupold Vari-X 3 3.5-10x40mm;
Or... the test will be performed with 165 gr Remington Core-Lokts in a .30-06 Marlin XL7 topped with a Redfield Revolution 3-9x40mm . (The Bushnell 4200 Elite was crap. I had to swap it for the Redfield.)
Either load is know-good (less than half MoA for both, actually). Minor tweaking will be expected, to get optimum accuracy out of the crimped version. We'll see what happens. I'll be honest about the data.