[tumblindice]

I was going to ask if you could put a 6.5 Grendel upper on a 5.56 lower, but from this Guns and Ammo survey it looks like most shooters prefer .223/5.56 as `best all around (varmint) cartridge’.
That 6.5 is hard to find anyway, isn’t it?

.223/5.56mm NATO 43.4% (12,247 votes)

6.5 Grendel 23.96% (6,762 votes)

.300 Blackout 14.49% (4,088 votes)

6.8 SPC 13.53% (3,817 votes)

Other (Comment Below) 2.73% (771 votes)

5.45x39mm 1.89% (535 votes)

Total Votes: 28,220

[Ancesthntr]

“I was going to ask if you could put a 6.5 Grendel upper on a 5.56 lower”

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Yes. In fact, the Grendel was specifically designed to fit the standard AR-15/M-4/M-16 magazine’s. Same bolt, too. You really just need a new barrel.

[B4Ranch]

It all depends on what you are building the rifle for. For extreme accuracy, formidable terminal ballistics and long range applications, the 6.5 Grendel from Alexander Arms is unbeatable. Under 500 yards the 5.56 would be my choice, over 500, the Grendel because you have a much larger choice of bullets to sort through as you reach further out.