Do Spike's lowers fit PSA uppers?
Spike's lower + PSA upper: yes, they fit
Yes. Spike's Tactical 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. Spike's and PSA AR-9 (9mm) lowers and uppers fit each other too.
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 October 31, 2026.
Our take
Most built setup: the Spike's Tactical Spider lower with the PSA Upper 5.56 16in Mid-Length.
PSA is one of the most picked upper brands on Spike's lowers.
Spike's Tactical makes AR rifles, uppers, lowers and parts in Florida, with the Spider logo on the lowers. The T3 tungsten buffer is one of their most known parts.
Founded 2001, Apopka, Florida, 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
Spike's 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-9 (9mm) | Yes, they 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 Spike's lower
Spike's Tactical Spikes Tactical M4 Lower Receiver$274.99and this PSA upper
PSA Upper 5.56 16" Mid-Length Nitride 13.5" M-LOK$219.99AR-9 (9mm): yes, they fit
Both are AR-9 receivers. A 9mm lower takes the upper's 9mm.
Checked on this Spike's lower
Spike's Tactical Spider 9mm Lower$161.10and this PSA upper
PSA GEN4 8" 9mm 1/10 Suppressor Ready 10" M-LOK Upperout of stockMost built Spike's lowers and PSA uppers setups
Ranked by how often builders pick the exact pair. Only pairs our rules pass are listed.
#1Yes, they fit4% of these buildsCheck fit
#2Yes, they fit3% of these buildsCheck fit
#3Yes, they fit2% of these buildsCheck fit
#4Yes, they fit2% of these buildsCheck fit
#5Yes, they fit2% of these buildsCheck fit
#6Yes, they fit2% of these buildsCheck fit
#7Yes, they fit2% of these buildsCheck fit
#8Yes, they fit2% of these buildsCheck fit
What Spike's and PSA say
Spike's: The Spider stripped lower is forged 7075-T6 with a Type III Class 2 hard coat anodized finish.
Spike's: Spike's 9mm Glock Gen II billet set comes with last round bolt hold open and the ejector, and the upper has no dust cover, forward assist or brass deflector.
Spike's: Spike's 9mm Spider lower comes in a Colt version with a dedicated Colt mag well and a Glock version with a Glock mag well and last round bolt hold open.
Spike's: Spike's stripped lowers take standard .154 inch trigger and hammer pins.
PSA: PSA owns its supply chain, including Spartan Forging and DC Machine, from forging the receivers to finishing the muzzle brake.
PSA: PSA's PX-9 lower takes Glock style magazines, is designed to work with PSA's 9mm Hybrid uppers and has no last round bolt hold open.
PSA: PSA's PX-9 Glock lower works with most AR-9 uppers, including Aero, Daniel Defense, Foxtrot Mike and Bear Creek, though non PSA uppers can see some tolerance stacking.
PSA: The KS-47 Gen2 bolt has two lugs reshaped so it feeds from AK magazines.
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 Spike's lowers
- Spike's lowers + BCM uppersMost picked
- Spike's lowers + Aero uppersThird most picked
- Spike's lowers + Geissele uppersFourth most picked
- Spike's lowers + Spike's uppersFifth 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
- Sharps Bros lowers + PSA uppersSixth most picked
Spike's lowers and PSA uppers: questions builders ask
Will a PSA upper fit a Spike's lower?
Yes. Spike's 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.
Why might a PSA upper feel loose or tight on a Spike's 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.