What lower is best for 9mm AR?

[patrickbeijer]

I currently run a 9mm AR with mill spec lower and hahn toploading block but i want to switch to a glock mag lower. I can get 

my hands on a Critical Components or a quarter circle 10 lower (live in Europe so not many choices)      At this time i also own a MP5 and a sig mpx but for competitve shooting i like the AR more.. which lower of the above would be the best choice ? The rest of the 9mm Ar is Odin 16” barrel , colt 9mm receiver and JP bolt and paper city handguard ,trigger i use is mill spec hammer with JP trigger since all my others (geissele , hyperfire, Elf9 ) seem to break...

[RangerTrace]

I'd say keep what you have and buy more ammo.  I like the flexibility of being able to use mine as a 9MM SBR or remove the block and make it whatever I want.

[patrickbeijer]

I am a gundealer and have no ammo problem but i like having a very competitive gun

[RangerTrace]

What does having a dedicated Glock lower have to do with being competitive?

[stick]

If you want a dedicated lower then get the QC10.  

[Smithcity]

If your MPX runs...it's close enough to AR controls, I'd start there. If you really want an AR in 9mm, you need to marry a barrel, upper, and lower together that presents the magazine at an appropriate angle / height for reliable feeding. I've seen to many barrel / upper / lower combinations that don't feed reliably. I have an New Frontier Armory upper/lower combo with QC10 barrel that works "best" for me. By "best" I mean it feeds round nose reliably, and has issues feeding hollow points 2-5% of the time. 

 

The JP's I've seen feed everything reliably, but they control the 3 key aspects for reliable feeding. The Radial Delayed Blowback by CMMG also feeds reliably from what I've seen (speaking based off of observations of friends guns), again, CMMG is controlling the 3 important components.

 

In short, if you want it to be reliable, might be best to get an upper / lower / barrel that are from the same manufacturer with a record of reliable feeding. Franken-build your own combination at risk of unreliable feeding.

[mahamoti]

3 hours ago, RangerTrace said:

What does having a dedicated Glock lower have to do with being competitive?

 

Reloading even the best mag block sucks.

[Stuey]

I'd say keep what you have and buy more ammo.  I like the flexibility of being able to use mine as a 9MM SBR or remove the block and make it whatever I want.

This is the best advice to go with. Work with what you got, shoot it till it breaks, fix it and shoot some more.

Just having the best and greatest is not going to make you better. I have been there and done that.


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[blaster113]

QC10 has an AR lower which takes MP5 mags as another option.  I wish they made one that'd take 10mm MP5 mags, but thats another story. 

[Patrick Scott]

Dont know if they are the best, but I have had great luck with the two QC10 Glock lowers I have. 

[Judo]

Quarter Circle 10

Edited July 31, 2018 by Judo

[biggulp]

I had the same question and did the same research (except I wanted Colt pattern).  As most everyone else said, QC10 is the way to go.

 

It's more expensive than the Critical Capabilities lower, but in this case you can see and feel the quality difference.  It's not just the actual finish (which is nice), but also the little touches like the flared magwell and a few things like that.

 

 

[wyliearms]

"Best" is subjective.