Do CMMG lowers fit PSA uppers?
CMMG lower + PSA upper: yes, they fit
Yes. CMMG AR-15 lowers fit Palmetto State Armory (PSA) AR-15 uppers. Both are AR-15 size receivers. A real mil-spec keeps AR-15 receivers from different makers close, though not exact, and fit problems show up most when the upper and lower come from different makers. We checked them with the rules the AR builder runs.
One exception: CMMG AR-15 lowers are a smaller frame and do not fit PSA AR-10 (.308) uppers. One catch: AR-10 parts aren't standardized between makers, so ask CMMG and Palmetto State Armory if this lower and upper fit before you buy.
Fit comes from the same rules the AR builder runs on every part you add. Build data only ranks the setups; it never decides fit. Checked November 10, 2026.
Our take
Most built setup: the CMMG MK4 .223 Remington AR Lower with the PSA Upper 5.56 16in Mid-Length.
About 1 in 10 CMMG lowers in our builds carries a PSA upper.
CMMG makes complete AR rifles, pistols and parts, and it's known for Radial Delayed Blowback, its action for pistol caliber ARs in rounds like 10mm and .45 ACP.
Founded 2002, Boonville, Missouri, Made in USA
PSA sells affordable AR lowers, uppers, BCGs and complete rifles, and it makes them in house from forging to finished part.
Founded 2008, Columbia, South Carolina, Made in USA
CMMG lowers and PSA uppers by platform
Each row is checked on the most built part of that platform from each brand.
| Platform | Fit |
|---|---|
| AR-15 | Yes, they fit |
| AR-10 (.308) | They fit, with a catch |
| AR-15 lower + AR-10 (.308) upper | No, they do not fit |
AR-15: yes, they fit
Both are AR-15 size receivers. This multi caliber lower takes the upper's 5.56 NATO.
Checked on this CMMG lower
CMMG MK4 .223 Remington AR Lower$100.02and this PSA upper
PSA Upper 5.56 16" Mid-Length Nitride 13.5" M-LOK$259.99AR-10 (.308): they fit, with a catch
AR-10 parts aren't standardized between makers, so ask CMMG and Palmetto State Armory if this lower and upper fit before you buy.
Checked on this CMMG lower
CMMG MK3 Semi-automatic Stripped Lower Receiver 308$204.99and this PSA upper
PSA GEN3 PA10 20" Rifle-Length .308 WIN 1:10 Stainless$499.99AR-15 lower + AR-10 (.308) upper: no, they do not fit
The lower receiver (.223 Wylde / 5.56 NATO / Multi) cannot support a AR-10/.308 build.
Checked on this CMMG lower
CMMG MK4 .223 Remington AR Lower$100.02and this PSA upper
PSA GEN3 PA10 20" Rifle-Length .308 WIN 1:10 Stainless$499.99Most built CMMG lowers and PSA uppers setups
Ranked by how often builders pick the exact pair. Only pairs our rules pass are listed.
#1Yes, they fit9% of these buildsCheck fit
#2Yes, they fit6% of these buildsCheck fit
#3Yes, they fit6% of these buildsCheck fit
#4They fit, with a catch6% of these buildsCheck fit
#5They fit, with a catch3% of these buildsCheck fit
#6They fit, with a catch3% of these buildsCheck fit
#7They fit, with a catch3% of these buildsCheck fit
#8They fit, with a catch3% of these buildsCheck fit
What CMMG and PSA say
CMMG: A CMMG DISSENT upper fits most of CMMG's BANSHEE, RESOLUTE and ENDEAVOR lowers only after you pull the buffer tube and stock and install the adapter plate that comes with the upper.
CMMG: CMMG does not guarantee its DISSENT runs right with mil-spec or other aftermarket triggers.
CMMG: CMMG's Mk3 .308 platform is based on the DPMS LR-308 Gen 1 high pattern design.
PSA: PSA owns its supply chain, including Spartan Forging and DC Machine, from forging the receivers to finishing the muzzle brake.
PSA: PSA's Gen3 PA10 lowers work with Gen1 and Gen2 PA10 uppers, but Gen3 with Gen3 is recommended for the best look and performance, since mixed generations differ on the outside.
PSA: The PSA PA-10 follows the DPMS pattern, so it can use a wide range of DPMS style parts.
PSA: The AR-10 has no common design across makers the way the AR-15 does, so use only PSA PA10 parts in PSA's PA10 receivers and not other makers' parts.
Fit is judged from the specs retailers list, which can be missing or wrong. Confirm with the manufacturer before you buy, and have a qualified gunsmith check any build before you fire it.
Other uppers builders put on CMMG lowers
- CMMG lowers + CMMG uppersMost picked
- CMMG lowers + Aero uppersSecond most picked
- CMMG lowers + TacFire uppersThird most picked
- CMMG lowers + BCM uppersFourth most picked
Other lowers under PSA uppers
- PSA lowers + PSA uppersMost picked
- Aero lowers + PSA uppersSecond most picked
- Smith & Wesson lowers + PSA uppersThird most picked
- Wilson Combat lowers + PSA uppersFourth most picked
- Spike's lowers + PSA uppersFifth most picked
- Sharps Bros lowers + PSA uppersSixth most picked
- Griffin Armament lowers + PSA uppersSeventh most picked
- LMT lowers + PSA uppersEighth most picked
CMMG lowers and PSA uppers: questions builders ask
Will a PSA upper fit a CMMG lower?
Yes. CMMG AR-15 lowers fit PSA AR-15 uppers. Both are AR-15 size receivers.
Do I need a matched upper and lower?
A real mil-spec keeps AR-15 receivers from different makers close, though not exact, and fit problems show up most when the upper and lower come from different makers.
Does a CMMG AR-10 lower fit a PSA upper?
CMMG AR-10 (.308) lowers fit PSA AR-10 (.308) uppers, with one thing to check. AR-10 parts aren't standardized between makers, so ask CMMG and Palmetto State Armory if this lower and upper fit before you buy. CMMG AR-15 lowers are a smaller frame and do not fit PSA AR-10 (.308) uppers.
Why might a PSA upper feel loose or tight on a CMMG lower?
Some play between an AR-15 upper and lower is common, but it can get excessive when the two come from different makers, and a tension screw or an Accu-Wedge takes it up.