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Reviews & Ratings for Rock River Arms A4 .450 Bushmaster Completed Upper — 4 reviews

(4 reviews)
Rock River Arms A4 .450 Bushmaster Completed Upper
Rock River Arms A4 .450 Bushmaster Completed Upper
As Low As $584.20 Save Up to $60.01
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Most Helpful Positive Review Rock River 450 FTW!
Dunno what the deal was with the 1 star review I saw the other guy submit. I have had zero malfunctions out of about 80-100rds. Running it on a rifle buffered, ace stocked lower as god intended. Accuracy has been extremely impressive with the hornady custom 250’s through this chonky boi. Holding a ...
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Most Helpful Negative Review .450 Rock River A4 uppers
Bought 2 uppers and neither of them cycled so I sent them back and got 2 new Uppers and now they are still doing the same thing. Rounds don't eject and bolt doesn't stay open once mag is empty. I am returning these items because it seems like the quality assurance is not there. I was really hoping f...
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450 BM upper receiver

by Z, Verified Owner from CO, United States Written on April 10, 2025
Great upper. Haven't fired it yet but will this weekend. I can't say enough good about Optics Planet. They shipped this fast so it would get to Colorado before our communist tax bill went through. The 2A community is absolutely amazing.
Pros:
  • It's a Rock River Arms. Quality is always over the top.
Cons:
  • None yet.
Best Used for:
  • AR-15 lower receivers.
Would recommend: Yes
Was it helpful to you? Yes | No
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This upper won’t cycle

by Dustin Taylor, Verified Owner from TX, United States Written on March 2, 2025
I’m having issues with mine cycling the has block is aligned right I don’t know what to do it is very accurate but don’t cycle
Would recommend: No
0 of 1 found the following review helpful.
Was it helpful to you? Yes | No
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