AR-9mm Question?

[mccolm323]

Alright guys/gals,

I am building a AR-9mm and I might have a dummy question. The lower parts kit, same as a standard lower parts kit on a ar-15? I know that the upper/bolt/mag well insert are different. Thanks everyone!

[chillincody]

im not 100% but how I understand it . the standard ar 15 hammer doesnt work with a 9mm BCG but if you buy a ramped 9mm bolt then it will work with the ar 15 hammer also you need a 9mm buffer but other than that you should be GTG

[bonesurf]

Ok if you use a cmmg ramped bolt then you can use a regular hammer. If you use the RRA bolt you will need one of those .22lr/9mm hammers. Also due to the blow back nature of function the anti rotation (kns) kits are recommended though I'm honestly not exactly certain I understand that one. Finally buffer changes are recommended.


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[Intimid8tor]

Ok if you use a cmmg ramped bolt then you can use a regular hammer. If you use the RRA bolt you will need one of those .22lr/9mm bolts. Also due to the blow back nature of function the anti rotation (kns) kits are recommended though I'm honestly not exactly certain I understand that one. Finally buffer changes are recommended.


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Exactly right. Last I checked, cheaper than dirt had the best price on the CMMG bolt.

The 9mm system, especially with the RRA bolt seems to be much harder on the pins and holes. Has to do with how quick the hammer is reset due to no ramping. I think it is just a little extra insurance.

[JPurp]

Standard lower parts kits if you are using a magwell adapter. The upper is the same though you can go with a slabside upper, the forward assist and shell deflector aren't used or 9mm. The ejection port cover is different.

I have two 9MM ARs and I highly recommend the CMMG ramped bolt. As was said before the ramped bolt and standard AR hammer are less stress on your pins.

I also have one of the CMMG MK-9 dedicated lowers and I like the fit and function better than the mag well adapters. There is one issue to note the bolt catch doesn't consistently get tripped with C Products magazine plastic followers.

-JP

[NSR500]

Ramped bolt and KNS anti-rotation pins FTW.

[mccolm323]

Thanks everyone for the info, as always very helpful!

[bonesurf]

Don't forget the 9mm buffer. Fwiw with my carbine length buffer tube I couldn't get a spikes 9mm buffer to work. My bolt wouldn't rack. RRA bolt and some quarters in back to limit excursion works though. They say that if you don't limit bolt excursion you get extractor (?) breakage.

[ch3ck5ix]

Don't forget the 9mm buffer. Fwiw with my carbine length buffer tube I couldn't get a spikes 9mm buffer to work. My bolt wouldn't rack. RRA bolt and some quarters in back to limit excursion works though. They say that if you don't limit bolt excursion you get extractor (?) breakage.

Heavy buffer and spacer (or ~2 bucks worth of quarters) to reduce the bolt inertia and reduce the bolt travel as insurance to prevent breakage of bolt catch, hammer/trigger pins and/or egging out the hammer/trigger pin holes.

[CHS]

Ramped bolt and KNS anti-rotation pins FTW.

If you have a ramped bolt carrier then you don't need the KNS pins as the ramped carrier fixes the original problem.

[CHS]

They say that if you don't limit bolt excursion you get extractor (?) breakage.

It's the bolt-stop that breaks, actually.

[NSR500]

The ramped bolt might not need it, but I like the insurance of the KNS pins.

[mccolm323]

Awesome! Thanks

[foOlio]

I went with a 9mm-q buffer.

http://www.heavybuffers.com/ar15carbine.html

[johnny1290]

I'd love to see the specs on your build if you have time. I'd love to have one of these, they're just so darn pricey.