Do LMT lowers fit PSA uppers?
LMT lower + PSA upper: yes, they fit
Yes. Lewis Machine & Tool (LMT) 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: LMT AR-15 lowers are a smaller frame and do not fit PSA AR-10 (.308) uppers.
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 LMT MARS-LS PDW lower with the PSA Upper 5.56 16in Mid-Length.
About 1 in 20 LMT lowers in our builds carries a PSA upper.
LMT, now LMT Defense, makes rifles for militaries around the world. On the parts side it's known for the MRP monolithic upper and the Enhanced Bolt.
Founded 1980, Eldridge, Iowa, 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
LMT 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-15 lower + AR-10 (.308) upper | No, they do not fit |
AR-15: yes, they fit
Both are AR-15 size receivers. An AR-15 lower takes the upper's 5.56 NATO.
Checked on this LMT lower
LMT MARS-LS PDW Lower Receiver$989.99and this PSA upper
PSA Upper 5.56 16" Mid-Length Nitride 13.5" M-LOK$259.99AR-15 lower + AR-10 (.308) upper: no, they do not fit
The lower receiver (AR-15) cannot support a AR-10/.308 build.
Checked on this LMT lower
LMT MARS-LS PDW Lower Receiver$989.99and this PSA upper
PSA GEN3 PA65 20" Rifle-Length 6.5 Creedmoor 1/8$519.99Most built LMT lowers and PSA uppers setups
Ranked by how often builders pick the exact pair. Only pairs our rules pass are listed.
#1Yes, they fit8% of these buildsCheck fit
#2Yes, they fit8% of these buildsCheck fit
#3Yes, they fit8% of these buildsCheck fit
#4Yes, they fit6% of these buildsCheck fit
#5They fit, with a catch4% of these buildsCheck fit
#6Yes, they fit4% of these buildsCheck fit
#7Yes, they fit4% of these buildsCheck fit
#8Yes, they fit4% of these buildsCheck fit
Watch the frame size. Builders also pair parts our rules say do not fit, like these two: Lower Receiver (6.5 Creedmoor) cannot support an AR-15 Standard (5.56/.223/.300 BLK etc.) build.
What LMT and PSA say
LMT: The MRP upper is machined from a single 7075-T6 forging with the rail built in, and it's set up for quick barrel swaps.
LMT: LMT's MWS .308 lowers are only guaranteed to work with LMT uppers, and other brands may not fit or run right.
LMT: LMT's ambidextrous MARS-H .308 lower is known to work with other uppers, but pairing it with an LMT upper is the safe choice.
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 LMT lowers
- LMT lowers + BCM uppersMost picked
- LMT lowers + Daniel Defense uppersSecond most picked
- LMT lowers + Geissele uppersThird most picked
- LMT lowers + LMT uppersFourth most picked
- LMT lowers + Aero uppersFifth most picked
- LMT lowers + TacFire uppersEighth 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
- Anderson lowers + PSA uppersNinth most picked
LMT lowers and PSA uppers: questions builders ask
Will a PSA upper fit an LMT lower?
Yes. LMT 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 PSA AR-10 upper fit an LMT lower?
LMT 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 an LMT 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.