Does the Foxtrot Mike Products FM9 Premium 9mm work with the Stern Defense SD 4in MOD4 M-LOK 4in?

Foxtrot Mike Products Complete Fm9 Premium 9mm Ar-15 Lower Receiver

Lower Receiver

Foxtrot Mike Products FM9 Premium 9mm

from $275.00

Stern Defense SD 4in Mod4 M-Lok 4in Barrel 9mm Black Complete Upper Receiver Black SDINBRLKK

Upper Receiver

Stern Defense SD 4in MOD4 M-LOK 4in Barrel 9mm SDINBRLKK

from $419.27

Foxtrot Mike Products lower and Stern Defense upper compatibility

Yes, they fit

The Foxtrot Mike Products FM9 Premium 9mm works with the Stern Defense SD 4in MOD4 M-LOK 4in Barrel 9mm. Our compatibility rules found no conflict between them.

This exact setup is in a real GunPartPicker build.

Counted from real GunPartPicker builds: parts lists people put together while planning to buy.

Checked by the same rules the AR builder runs on every part you add: caliber, frame size, receiver pattern, thread pitch and gas length.

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.

How often builders pair the Foxtrot Mike Products lower and Stern Defense upper

Backed by tens of thousands of qualified builds that have both a lower and an upper.

Upper Receivers builders put on the Foxtrot Mike Products FM9 Premium 9mm

Share of builds with the Foxtrot Mike Products FM9 Premium 9mm and any upper

Lower Receivers builders put under the Stern Defense SD 4in MOD4 M-LOK 4in

Share of builds with the Stern Defense SD 4in MOD4 M-LOK 4in and any lower

  • Foxtrot Mike Products FM9 Premium 9mm

    Of lower picks
    1.3%
    Median paid
    $275

  • Stern Defense SD 4in MOD4 M-LOK 4in

    Of upper picks
    0%
    Median paid
    $419
How we count ⌄

These shares come from GunPartPicker's build data: real parts lists people put together while planning a purchase, not sales or surveys. A build counts a part only when it is the final pick for its slot, so parts that were swapped out never count. Fit never comes from these numbers; it comes from our compatibility rules alone.

Frequently built with the Foxtrot Mike Products lower and Stern Defense upper

The part builders pick most often in each slot alongside these two, checked against both. Parts that conflict are left out.

Trigger

Stock & Brace

Charging Handle

Optic

Light

Bolt Carrier Group

Foxtrot Mike Products FM9 vs Stern Defense SD 4in MOD4: specs and prices

Foxtrot Mike Products FM9Stern Defense SD 4in MOD4
Best price$275.00 at Primary Arms$419.27 at Optics Planet
Stores0 of 1 in stock1 of 1 in stock
AssemblyCompleteComplete
PlatformAR-9AR-9
Caliber9mm9mm
Trigger Pin.154n/a
FinishHardcoat Anodizedn/a
Lengthn/a4

Both for $694.27 at today's best prices.

Today's best prices and 90 day price history

Every store we track for each part, cheapest in stock first. Prices are checked through the day.

Foxtrot Mike Products FM9 Premium 9mm

Stern Defense SD 4in MOD4 M-LOK 4in Barrel 9mm

Price history, last 90 days

  • Foxtrot Mike Products FM9 Premium 9mm: lowest $275.00 on Jul 7, highest $275.00 on Jul 7 over the last 90 days.
  • Stern Defense SD 4in MOD4 M-LOK 4in: lowest $376.96 on Jul 5, highest $419.27 on Jul 12 over the last 90 days.

Upper Receivers frequently paired with the Foxtrot Mike Products FM9 Premium 9mm

Most picked next to it in real builds. Only parts our rules say fit the Foxtrot Mike Products FM9 Premium 9mm are listed.

Lower Receivers frequently paired with the Stern Defense SD 4in MOD4 M-LOK 4in

Most picked next to it in real builds. Only parts our rules say fit the Stern Defense SD 4in MOD4 M-LOK 4in are listed.