there are always questions about 9mm AR15 builds that pop up every so often. i've decided to document my build; this is my second build so i know that finding info doing my first one was a pain. hopefully this takes some of the mystery out of building a 9mm for someone who has never done it before.
first off, this is by no means the only way to do it nor the best way. it's just the way i happened to do it.
when reading through this thread, remember to take into account that i based this build on the parts i already had, the parts that are currently available, and my budget.
this is also a theme build. i've been wanting to go with a 9mm AR for SSA and i've also decided sometime ago that for a future build i wanted to do a mk 18 style AR. yes, i know that a mk 18 is not 9mm, but whatever, i still wanted to build a mk 18 looking AR so i decided to meld the two projects into one.
here is what a suppressed mk 18 (or replica) looks like. (not my pic, i took this from another forum and forgot where and from whom i took it from. to that person, i say thanks!)
PARTS & COST:
so now that i have a theme and purpose set, let's get the parts together.
stuff i bought for this build (not including tax, dros, or shipping):
kd calguns lower - $99
lmt sopmod stock - $175
milspec buffer tube - $30
raddlock - $35
spike's 9mm ST-9X buffer - $50
rra 9mm buffer spring - $4
spike's 9mm M4 profile 16" barrel - $165
cmmg 9mm bolt - $150
hahn dedicated 9mm mag block - $160
magpul miad grip (basic) - $33
yhm upper receiver - $75
forward assist assembly - $9
colt 9mm upper ejection port door and gas deflector - $22
kac uk sas ras rail - $200
mfi kac style fake suppressor + 1.5" adapter - $125
aimpoint m2 on wilcox mount - $350
c products 10 round mags (2) - $40
stuff i already had (not including tax, dros, or shipping):
lower parts kit - $70
charging handle with badger gen 2 latch - $40
lmt rear sight - $110
dez arms set screw type A2 FSB - $25
delta ring assembly - $0
ejection port cover pin and clip - $5
hand guard front ring - $0
kns trigger and hammer pins - $25
kac vertical foregrip - $25
magpul bad - $29
not shown, magpul/ergo rail ladders (2) - $22
so the grand total (not including tax, dros, or shipping) is: $2,073
the prices are rounded up, some items were bought during "the rush" so they are probably a lot less now.
here are a few key notes of parts that i got and why:
cmmg 9mm bolt:
unlike the rra one, this one comes ramped to accept standard AR (rounded head) hammers. no need for a special 9mm hammer.
spike's 9mm M4 profile barrel:
for my first build i was stuck getting a rra barrel which turned out to be a heavy profile barrel which completely sucked. the barrel was fine, it was the weight that made me not want to shoot it and eventually i sold it. so this time around, i wanted lighter.
spike's ST-9X buffer:
it's heavier and longer than even an H2 buffer. i used this in my first build with great results, so i went with it again. the extra length helps keep your bolt catch from breaking.
hahn dedicated mag block:
i had this on my first build. love it. it has the bolt lock back on empty mag feature and is dedicated, which means no need for adjustment to get it working. (at least in my experience) there are other brands out now, but i just went with what i knew.
YHM/COLT upper assembly:
i bought the YHM upper used for $75 + $9 for the forward assist (which i don't need but i didn't want to leave a hole and it added to the mk 18 look) + the colt 9mm ejection port parts for $22 still was a cheaper route to go than to have bought a 9mm upper. typically $140-150. btw, the 9mm plastic ejector port thing is a gas deflector, not a shell deflector. i learned this after burning time doing research trying to find a 9mm shell deflector. there is no such thing.
KNS Trigger and Hammer Pins
- needed because the 9mm action is harsher than .223/5.56 so it is said that the regular hammer pin snaps. this is up for debate, but i had them anyway so i used them.
MFI fake suppressor:
i went with this for my mk 18 theme. it looks a lot like KAC's suppressor and helps me make my 16" barrel look 10.5" which is what a mk 18 has. if you want the same look, go with a 1.5" spacer with your MFI. remember that the 16" barrel sinks into the upper receiver about an inch more than a standard .223/5.56 barrel due to the lack of a barrel extension. so you actually need to extend your barrel a little bit for the MFI to fit. a .75" would have been better but it was a $35 up charge, so i stuck with the 1.5". in the end, my 9mm upper and a real mk 18 suppressed upper will deviate by only about .25" - mine being longer.
DEZ Arms A2 FSB:
the 9mm system does not need a gas block but i wanted an A2 FSB for the mk 18 look anyway. so, i opted for the easy install of a set screw FSB that DEZ arms makes. it still mounts very solid.
ok, assemble as per calguns or arfcom instructions. if this is your first build, take your time. there are tons of parts to lose or to put together in the wrong order. don't do that.
i've done so many now that this took me about an hour and twenty minutes. i burned some time finding out that the KAC RAS needed to be modified in order to fit over the spike's barrel. even though it is advertised as an M4 profile barrel, the part that is under the hand guard remains a heavy profile. i was kinda bummed at that since i was looking to shave off weight to offset the weight of the MFI fake suppressor. i had to knock off a pin and take off a part of the RAS from the underside. so this upper is still heavier than i would like, but lighter than my last build so i'll live.
viola, here it is assembled:
looks a lot like the pic i based my theme after, doesn't it?:
some more beauty shots: