Sig Sauer

SIG SAUER SIGMCX 300 Blackout 9in 30rd FDE Semi-Auto Rifle (RMCX-300B-9B-IR-SBR)

SIG SAUER SIGMCX 300 Blackout 9in 30rd FDE Semi-Auto Rifle (RMCX-300B-9B-IR-SBR) - Complete Rifle - view 1
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Sig Sauer

Overview

The SIG SAUER SIGMCX 300 Blackout 9in 30rd FDE Semi-Auto Rifle (RMCX-300B-9B-IR-SBR) is a complete rifle. Compare prices from multiple merchants and find the best deal.

Specifications

MPNRMCX-300B-9B-IR-SBR
PlatformAR-15
Caliber300 Blackout
Gas System LengthPistol
Thread Pitch5/8x24
Action TypeSemi-Auto
Twist Rate1:5
ColorFDE
Barrel Length9.0
ComplianceStandard

Available Merchants(3)

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Brownells
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$2,500
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BattleHawk Armory
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$2,500
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KY Gun Company
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$2,500
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Build history on GunPartPicker

Builders on GunPartPicker first added the SIG SAUER SIGMCX 300 Blackout 9in 30rd FDE Semi-Auto Rifle (RMCX-300B-9B-IR-SBR) to a build in May 2026.

It was out of stock everywhere we track for all of September 2026, and today none of the 3 retailers we track has it in stock right now. Listed prices start at $2,499.99 at Brownells for when it comes back.

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