JJCII,
Your headspace may very well check out, as the headspace dimension doesn't include the bullet in the measurement. Headspace is measured from a "datum line", about midway of the shoulder, to the base of the cartridge. The long throat in the FR-8's was to clear the longer,heavier bullets in the Spanish rounds.
I wouldn't worry too much tho', as your groups indicate that something is working right. These were not built to be as accurate as a good sporter, just to reliably kill in a combat environment. Still, I'd check headspace & probably do a chamber cast just to add a little peace of mind. Sounds like you got a good 'un.:0
My previous post was meant only to inform, so that you could make an educated decision about reloading or rebarreling, depending on your needs. Hope this helps.