I have all the parts to convert one of my AR10s to 6.5CM. How important is the HP bolt some manufactures sell? I will be running a JP adjustable gas block as well.
It is the most important part of a 6.5CM build next to using a extended rifle length system.
Why is it that important? Are cratered primers really that big of a deal for people?
The standard firing pin hole will not let you get anywhere near the potential of the cartridge when reloading due to the high-pressure nature of the 6.5 CM or a 260 you'll get more than just cratering primers, blown and pierced primers are very common especially with some of the hotter loads from companies like Horniday.
In my experience with it, I would get all the proper parts. AR10s weren't originally designed to work with suck high pressure rounds.