02-06-2012, 07:04 PM
I can't offer any insight into ARP but I can offer some experience on 5R rifling. It is as good as it gets but no better than standard six groove if all other variables are held constant. I have a couple of nearly identical Kriegers with 5R and six groove. They shoot identically too. There is no advantage, and there is no disadvantage. I will say my best shooting Garand has an Obermeir 5R barrel on it, but it was smithed by Don McCoy, double lugged, tuned op rod and all that stuff and it shoots good, but again, no better than my friends Don McCoy with a Krieger six groove.
Bob
Bob