Which 9mm AR upper???

[DocIndy]

I've been thinking of getting one for a while and just wanted some input. Are there any out there to stay away from? It will be used on a .223 lower and which mag adapter is best? Flattop upper is a plus.

 

[bigcraig]

The best magwell adapter is by FAR the Hahn, but it is also the most expensive.

All of the following make good 9mm uppers.

Colt-if you can find one.
RRA
CMMG
Spikes

For trouble free 9mm use, remember the following.

Use a rounded hammer, use none with any notches.
Use the heaviest buffer and spring combo you can find.
When installing your mag-block, you might need to make some minute adjustments if using a "drop in" block, the dedicated blocks are a bit more precise upon installation.
Steer clear of light hammer springs.

 

[8th SPS USAF]

9mm upper

I had a Colt preban M4 great gun, sold it and bought a RRA M4
FT. SBR'ed it and both uppers are great shooters. Very accurate.

 

[Ridgeway]

I've been using a RRA upper & mag block w/o any problems. It has functioned 100%.

 

[jd4320t]

The best magwell adapter is by FAR the Hahn, but it is also the most expensive.

All of the following make good 9mm uppers.

Colt-if you can find one.
RRA
CMMG
Spikes

For trouble free 9mm use, remember the following.

Use a rounded hammer, use none with any notches.
Use the heaviest buffer and spring combo you can find.
When installing your mag-block, you might need to make some minute adjustments if using a "drop in" block, the dedicated blocks are a bit more precise upon installation.
Steer clear of light hammer springs.

Great info. Thanks

 

[DocIndy]

So with a RRA upper, I would have to replace the hammer too? Are there any out there that the .223 hammer in the lower wouldn't need to be switched? Can I use the 9mm hammer with the .223 upper? RRA makes good stuff..... but I might be able to get my hands on the original 9mm AR....a Colt.

 

[revsaxon]

As long as its a non-notched rounded hammer, it should work. The one I have in mine right now I got from spikes and it was sold as a multi-caliber hammer (like pretty much everything else they sell).

It wasnt mentioned, but if you plan on going with a supressor, id suggest the gem-tech talon. Its a bit pricy and you need to find your own bolt, but its designed from the start to use a multi-mount silencer (and the new isis from thomson machine should fit it in theory), and ive shot thousands of rounds thru mine without a single problem.