AR-9 Builder
Over 1 million parts configured since 2020
Build a 9mm AR-9 pistol or carbine part by part and price it in real time. Pick a 9mm lower, then the upper, barrel, blowback bolt, buffer, handguard, trigger and optic. GunPartPicker flags 5.56 barrels and bolts that do not match a 9mm lower and compares live prices across 35+ retailers so you can see what the full build costs before you buy.
Not sure where to start? The AR Build Cost Calculator fills every slot with the part builders add most, in stock, and prices the whole build.
AR-9 build basics
- Most AR-9s run straight blowback: no gas block or gas tube, and a heavier buffer instead.
- An AR-9 needs a 9mm lower, a 9mm upper and barrel, and a 9mm blowback bolt. AR-15 barrels and bolts do not fit.
- Glock pattern lowers take Glock 17 and 19 magazines; Colt pattern lowers take Colt 9mm SMG magazines.
What parts do you need to build an AR-9?
A 9mm lower for Glock or Colt pattern magazines, a 9mm upper with a 9mm barrel, a 9mm blowback bolt, and a heavier 9mm buffer and spring. Then a trigger, grip, stock or brace, handguard and optic. A blowback AR-9 has no gas block or gas tube.
Can you use an AR-15 lower for an AR-9?
With a magazine well adapter for Colt or Glock magazines, yes, but the bolt usually will not lock back on empty without a 9mm specific last round hold open. A dedicated 9mm lower is the simpler build.
Glock or Colt magazines for an AR-9?
Glock pattern is the common choice now: the magazines are cheap and the same ones a Glock 17 or 19 uses. Colt pattern is the original 9mm AR magazine, from the Colt SMG.
Choose a part to start your build
Build an AR-15, AR-10 or AR-9
AR-15 Builder
5.56 NATO, .223 Wylde, 300 Blackout or 6mm ARC on a standard small frame lower. Every slot is checked for fit.
AR-10 Builder
.308, 7.62 NATO or 6.5 Creedmoor on a large frame lower. The builder flags small frame parts that will not fit.
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