Home Forums Hunting & Shooting AR and Tactical Rifles Convert from 6.8 SPC II to 6.5 Grendel

So lets say I'm pondering changing my Bison Armory 18" 6.8 SPC II to 6.5 Grendel, again going with an 18" barrel (maybe 20"?). So I need a barrel, and a bolt, do I need a whole carrier for some reason? Buffer/spring? Adjustable gas block? Mags? What mags feed 6.5 Grendel? I have a can of 6.8 and PRi mags as well, I'll look at trading that stuff off down the road, after I'm sure about the 6.5.
Anybody use Faxon barrels?

Barrel bolt and mags.

I use ASC mags and have been pleased.

The gas system should work in the switch.

I use my 556 rifle buffer/spring when i switch out uppers.

So, in a pinch you could probably use the 6.8 SPC mags for the Grendel. There's a youtube video of a guy saying only the follower is different in them. I honestly couldn't tell you. As mentioned you will need the barrel and BCG to make it convert over.

My grendel mags are the same as 6.8

Aren't 6.8 SPC II and .224 Valkaryie the same as well? I think so, and my son just bought a complete .224 upper from PSA.

You won't need a complete BCG for the conversion, just the bolt itself. Also, there are two types of Grendel bolts...you must get the correct one for the barrel. The original used a 7.62x39 bolt and the Type II Grendel bolt is recessed deeper. Make sure the one you get matches the chamber on your new Grendel barrel.

Oh boy, you’re going to get the hardcore Grendel fans horned up...pretty sure the type II (.136”) recess was designed for the original Saami Grendel. The type 1 and 2 business was started later (by BHW I believe). I’m also pretty sure that most all barrels other than BHW 264 LBC are being chambered to run with the .136” bolt. Like you said, best to double check though and it wouldn’t be a bad idea to buy a barrel and bolt together.

I dunno who started what...but I do know that if you buy a BHW barrel for 6mm LBC (or 6mm AR, 56mm Grendel, or whatever you wanna call it) you will need a 7.62x39 bolt. I do know it's possible to come up with incompatible parts. I think it's a good thing to warn anyone interested in converting or building.

That's okay, that's the kind of thing that is good to know. I will try my 6.8 mags before I sell/swap them, they are great mags (for a 6.8)

I’ll call 1st option on 6.8 stuff. LOL

Seconds.

Lol.

Is it just me because I do I like the idea that I could use the 6.8 brass for the .224 and vice versa should I get in a pinch. The 6.5 would be fine if I didn't want a .224 as well. What does the 6.5 do that the 6.8 won't ? Apparently I'm missing something.

kwg

No.

If you’re hand loading, there’s really not much either ‘can’t’ do, that the other ‘can’, until maybe 800-1k, and some newer 6.8 bullets are apparently getting into that bracket a bit. Grendel is deemed ‘better’ at the >400 work, but that’s range only in my mind, due to the lighter bullets both use and velocity/energy numbers. You’ve got more bolt in the lugs with the 6.8/224, and a broader pressure range than sanity allows with x39 bolt faces, if slightly less case capacity. You’ve got a case/bore that’s a bit more efficient for shorter barrels, if that matters. Possibly less feed issues, though that’s mostly been rectified. Your call. If you need slightly more case capacity and higher BC bullets for milking to 1k, then the Grendel is you....though if handloading everything, there’s a few folks running 6.5x43 (6.8 necked) cats, doing good stuff. On game, inside 400, with 90-115 bullets running 2600-3k, the 6.8 doesn’t get ‘bested’ by much in the AR15..... unless you want to use the same case, and go TAC 30/Herrett.....then you’re getting somewhere. If changes happen enough shortly to give me reloading back in my time syncs, I’ll probably start playing with the TAC and 224, and even 6x6.8. I think the cases has a lot going for it in the AR platform, if wanting a step up.

You really have to shoot the 6.5 Grendel yourself to get a feel for how much easier it is to hit with at longer distance; the numbers don't really tell the full story.

With that said, I don't think I'd take apart a good upper to change calibers; I'd just build another one. Nothing wrong with owning both and taking advantage of their capabilities.

I have a 6.5x43 wildcat (Six5 from AR15Performance). He has 4 barrels left and not making anymore. It's a fun little round. Resize with 6.8 FL bushing die, trim and load. He has a good amount of info on 68forums about this cartridge. If you want more info, PM me.

Fantastic synopsis of the 6.5 vs. 6.8 discussion. Best I've seen pretty much anywhere.

I'd have a 6.5 myself if I didn't already have a couple 6.8s. But like another poster said, why take apart a good upper? Just build another one and have a choice. It doesn't cost that much to build a good upper these days.