AR Pistol Build: Help Appreciated

[LRRPF52]

Thanks for all of the input everyone. I genuinely do appreciate it.

Those Lilja barrels seem like a good option. I'll keep following that thread for updates and try to see what prices would look like from rebby. Do you think the Lilja would do well with light steel-cased stuff? Is it overkill in terms of quality? How would that compare to the 11.5" AA barrel?

The main motivation for the takedown feature is a much higher level of possible portability and concealment. I estimate that an upper with a 12" barrel would be a little over 21" long, depending on how the barrel extension overlap plays out in reality, whereas the takedown options shorten that to 14" or so overall length for the longest part. For regular use, that probably doesn't matter very much. But I really like the idea of being able to fit a firearm as capable as a Grendel AR into a tackle box, child's backpack, or perhaps even a large purse.

That's probably just me, and that's ok. I'm not really sold on that aspect of the build yet anyway. I'm mostly curious about matching the "right" barrel and bolt for the ammo. I'm not expecting incredible accuracy or anything, maybe reliably under 3 MOA. Under 2 would be magical dream land expectations.

LRRPF52, was it the inaccuracy of the MGI system that turned you off to those styles of systems? I was hoping that being able to pick my own barrel would alleviate a good chunk of that. Also, the Havoc appears to have a sturdier lockup than the Hydra did. LaRue's PredatOBR seems to do pretty well with a takedown system. Maybe, I'm just fooling myself though. Also, it's easy to say now but, the weight increase isn't a big deal to me.

I started out just seeing what it would do with initial load development for velocity, as I was more focused on velocity at that time. I think it was still in that configuration when I let some of my nephews shoot it with AA 90gr TNT loads at 300yds on some 12" steel poppers, which it flattened with ease 1st-round hits for them.

I was mainly shooting .260 Rem out of a large frame at the time for all my LR work, while Grendel was just a side interest I was playing with in hopes to have a lighter rifle for military Sniper team competitions conducted in field settings, no KD ranges. Once I started to see how easy it was for a new shooter to get on the rifle and make 1st round hits, I decided to put it in a dedicated upper and not mess with the Quick Barrel Change system anymore.