Does the Smith & Wesson M&P15 Lower work with the Colt M4 LE6921ERP Upper Group 14.5in?

Smith & Wesson M&P15 Complete Lower 5.56x45mm/.223 Remington, Black - 812002

Lower Receiver

Smith & Wesson M&P15 Lower 5.56x45mm/.223 Remington

from $269.99

Colt M4 Le6921erp Upper Group 14.5in With Bcg

Upper Receiver

Colt M4 LE6921ERP Upper Group 14.5in

from $930.27

Smith & Wesson lower and Colt upper compatibility

Yes, they fit

The Smith & Wesson M&P15 Lower 5.56x45mm/.223 works with the Colt M4 LE6921ERP Upper Group 14.5in. Our compatibility rules found no conflict between them.

No one has built this exact setup yet, but Smith & Wesson lowers with Colt uppers are a common pairing.

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 Smith & Wesson lower and Colt upper

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

Upper Receivers builders put on the Smith & Wesson M&P15 Lower

Share of builds with the Smith & Wesson M&P15 Lower and any upper

Lower Receivers builders put under the Colt M4 LE6921ERP Upper Group 14.5in

Share of builds with the Colt M4 LE6921ERP Upper Group 14.5in and any lower

  • Smith & Wesson M&P15 Lower

    Of lower picks
    4.9%
    Median paid
    $270

  • Colt M4 LE6921ERP Upper Group 14.5in

    Of upper picks
    0%
    Median paid
    $930
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 Smith & Wesson lower and Colt 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

Bolt Carrier Group

Optic

Suppressor

Charging Handle

Light

Smith & Wesson M&P15 Lower vs Colt M4 LE6921ERP Upper Group: specs and prices

Smith & Wesson M&P15 LowerColt M4 LE6921ERP Upper
Best price$339.20 at Classic Firearms$930.27 at BattleHawk Armory
Stores4 of 6 in stock3 of 4 in stock
AssemblyCompleteComplete
PlatformAR-15AR-15
Caliber5.56 NATO5.56 NATO
ColorBlackn/a
Receiver Typen/aM4
Lengthn/a14.5

Both for $1269.47 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.

Smith & Wesson M&P15 Lower 5.56x45mm/.223

Colt M4 LE6921ERP Upper Group 14.5in

Price history, last 90 days

  • Smith & Wesson M&P15 Lower: lowest $269.99 on Jul 11, highest $420.99 on Sep 26 over the last 90 days.
  • Colt M4 LE6921ERP Upper Group 14.5in: lowest $886.99 on Jul 5, highest $1093.99 on Aug 24 over the last 90 days.

Upper Receivers frequently paired with the Smith & Wesson M&P15 Lower

Most picked next to it in real builds. Only parts our rules say fit the Smith & Wesson M&P15 Lower are listed.

Lower Receivers frequently paired with the Colt M4 LE6921ERP Upper Group 14.5in

Most picked next to it in real builds. Only parts our rules say fit the Colt M4 LE6921ERP Upper Group 14.5in are listed.