02-28-2018, 12:28 AM
Nope, any mil-standard upper works. The one caveat would be to check the feed ramp style on your barrel extension, (I would assume based on my experience that it would most likely be the M4 style), and make sure the upper has the appropriate feed ramps machined in. You don't want to put a M4 extension into an rifle feed ramped upper, it creates a lip where the bullet tip will catch or drag on, causing feeding problems. You can get away with a rifle extension in an M4 upper, but it's not ideal. Best to match the two.
From another thread here you can gather some knowledge from some guys on their experiences with various brands of uppers.
http://www.65grendel.com/forum/showthrea...ing-thread
I don't think you can go wrong with either Aero Precision, or Bravo Company Manufacturing; both are well reputed and excellently machined. The Aero has more of a reputation for being pretty (function AND form!), where the BCM is just a proven industry member that puts out top-shelf stuff in general. Aero has an upper that is a little more involved they designate as the M4E1, which has some extra material in the forging to give it racier lines and a unique appearance. I don't know if it has mil-spec dimensions or if there are other build complications, so if you decide to go that route do some checking.
For me, any upper I buy henceforth for Grendel, unless part of a billet set, will be a BCM M4. They just don't have problems, and you will always know you've got good stuff in hand. Incidentally, Primary Arms has theirs on sale for $99 and in stock. That probably won't last long. Unless they have unusually high numbers in stock. http://www.primaryarms.com/bravo-company...bcm4-ur-m4
Blem (blemmished) uppers are okay from either, this can save you money, (if you can find them). However, they may have a tick or two that needs a little TLC. If you're mechanically inclined, you can almost always take care of it quickly and simply. I've never gotten a blem part from a reputed manufacturer that was anything more than a scratch in the finish or discolored spot in the coating... I don't mind either.
KS
From another thread here you can gather some knowledge from some guys on their experiences with various brands of uppers.
http://www.65grendel.com/forum/showthrea...ing-thread
I don't think you can go wrong with either Aero Precision, or Bravo Company Manufacturing; both are well reputed and excellently machined. The Aero has more of a reputation for being pretty (function AND form!), where the BCM is just a proven industry member that puts out top-shelf stuff in general. Aero has an upper that is a little more involved they designate as the M4E1, which has some extra material in the forging to give it racier lines and a unique appearance. I don't know if it has mil-spec dimensions or if there are other build complications, so if you decide to go that route do some checking.
For me, any upper I buy henceforth for Grendel, unless part of a billet set, will be a BCM M4. They just don't have problems, and you will always know you've got good stuff in hand. Incidentally, Primary Arms has theirs on sale for $99 and in stock. That probably won't last long. Unless they have unusually high numbers in stock. http://www.primaryarms.com/bravo-company...bcm4-ur-m4
Blem (blemmished) uppers are okay from either, this can save you money, (if you can find them). However, they may have a tick or two that needs a little TLC. If you're mechanically inclined, you can almost always take care of it quickly and simply. I've never gotten a blem part from a reputed manufacturer that was anything more than a scratch in the finish or discolored spot in the coating... I don't mind either.
KS
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