I want to build an 80% G3-style rifle in .308. I don't think I can run .308 through a rifle chambered in 7.61x51. I would like to put the longest barrel available on it. I need to start with the receiver. Will this suffice https://hkparts.net/product/receiver-flat-hk-91-g3-ptr-cetme-ptr-p2320.htm or is there another company that sells everything I need?

So how hard are they to bend? I assume you will need some kind of fixture. It will be cool. If you buy a PTR91 for cheap, used, I assume you can switch all the nexesaary parts, and Voila! ( Vew-Ella!)

I’ve run commercial.308 through my clone without issue.

I only run .308 thru my Cetme clone. No issues whatsoever. Covers a lemon at 100 yds w/ shit steel case.

@gunsliquorstrippers

If you can find a barrel with an original
style muzzle profile & matching brake,
you can use it to tune your barrel
harmonics to match your load, if you
use quality ammo.

I tuned my bone stock 91 to shoot sub
1/2 minute with 168 gr Gold Metal Match.
Amazingly easy once I stumbled upon the
concept & made a couple of trips to the
range. Study up on the Browning BOSS
system for specifics, or hit me up here if
you want me to explain what I did in more
detail.

That was a lot of fun back in the day.

Edit to add: Ignore the text below. I was
just using the image to indicate the original
HK muzzle & brake design.