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Sig Sauer M400 16" .300 BLK Upper Receiver

Sig Sauer M400 AR-15 Upper Receiver, .300 BLK, 16" BBL, Magpul MOE Handguard

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Now available from SIG SAUER. SIGM400 .300 BLK16" SRP upper receiver complete assembly.

- .300 BLK
- 16" barrel
- Direct Impingement Gas Operating System with Rotating Bolt
- Hard Coat Anodized Finish
- Magpul MOE Handguard

Specs - More Info
Additional Info
SKU UAM400-300B-16-SRP
UPC Code 79868150032
Caliber .300 Blackout
Manufacturer Sig Sauer
Sights (detailed) None
Grips Magpul MOE Handguard (Black)
Barrel Length (in) 16.0 in
Accessory Rail Not Applicable
Warranty Warranty provided by Sig Sauer. Warranty information is available for Sig Sauer products at
Customer Reviews (2)
Very Accurate
This was my 1st Sig Upper out of several builds I have done. This is the most accurate of any other upper. I built a new S3G competition rifle with this and I am waiting for inventory to be available so I can get another for my hunting rifle build. Review by Ken (Posted on 5/22/2015)
Great Upper!
I used this upper on my last build and it is very accurate. I am building another and am waiting for them to be back in stock so that I can pick up another. The only change I made was to swap the A2 flash hider for a muzzle brake to help with muzzle rise during 3 Gun shoots. I have build numerous Ar's and used several different uppers but this is my favorite. I am also hooked on the 300 Blackout caliber. the one I am building now is going to be a hunting rifle rather than a competition one. Review by Ken (Posted on 4/3/2015)
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