School me on go to 9mm AR parts

[indianalex01]

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BCG - JP rifles has some of the best, second is any that copy their style... NO psa 1's period
buffer - dedicated 9mm extended buffer (7.5 oz minimum)
spring - 308 spring works good, more money XP or wolf
receiver extension - any mil-spec tube will work
barrel - Ballistic Advantage makes some good ones

I run 2 Colt 6991 10.5 inch carbine/pistol. One is full auto. I found that on the FA that a KAK 10 oz tungsten sliding weighted buffer and a regular carbine buffer works the best. On FA it slows the rate of fire down to about 850-900rps.
The simi auto l runs a Vltor H2A5 buffer just shy of 7 oz. I found that a 308 buffer spring gives to much speed as it slams another round home. I went to a regular carbine buffer spring after that. I’ve tried every combo and then some. These for me have worked out the best. It’s all subjective though.

Smokin338 seems like he has tried different combos as well. When it comes to 9mm AR’s there is no perfect combo. Both of us have tried obviously. I like what smokin338 has going except the 308 spring(not saying it’s bad). For me I like carbine buffer spring.