Yes. The case for all 3 rounds uses the same base diameter and rim thickness. It was one of the main criteria for making 300BLK that the only change needed from a 5.56 was a new barrel. Same BCG, same mags. You’re good to go!
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Cryptic .223 / 5.56 / .300 AAC Blackout Low Mass Steel Bolt Carrier Group (BCG)
Cryptic .223 / 5.56 / .300 AAC Blackout Low Mass Steel Bolt Carrier Group (BCG) Q&A
Question - Can it run all three calibers listed? My main concern i
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AR 15 Parts
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AR15 Upper Parts
Cryptic AR15 Upper Parts
Cryptic .223 / 5.56 / .300 AAC Blackout Low Mass Steel Bolt Carrier Group (BCG)
Cryptic .223 / 5.56 / .300 AAC Blackout Low Mass Steel Bolt Carrier Group (BCG) Q&A
Question - Can it run all three calibers listed? My main concern i
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AR 15 Parts
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AR15 Upper Parts
Cryptic AR15 Upper Parts
Cryptic .223 / 5.56 / .300 AAC Blackout Low Mass Steel Bolt Carrier Group (BCG)
Cryptic .223 / 5.56 / .300 AAC Blackout Low Mass Steel Bolt Carrier Group (BCG) Q&A
Question - Can it run all three calibers listed? My main concern i
Cryptic
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Gun Parts
Cryptic Gun Parts
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AR 15 Parts
Cryptic AR15 Parts
Cryptic .223 / 5.56 / .300 AAC Blackout Low Mass Steel Bolt Carrier Group (BCG)
Cryptic .223 / 5.56 / .300 AAC Blackout Low Mass Steel Bolt Carrier Group (BCG) Q&A
Question - Can it run all three calibers listed? My main concern i
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Cryptic .223 / 5.56 / .300 AAC Blackout Low Mass Steel Bolt Carrier Group (BCG)
Cryptic .223 / 5.56 / .300 AAC Blackout Low Mass Steel Bolt Carrier Group (BCG) Q&A
Question - Can it run all three calibers listed? My main concern i
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Cryptic .223 / 5.56 / .300 AAC Blackout Low Mass Steel Bolt Carrier Group (BCG)
Cryptic .223 / 5.56 / .300 AAC Blackout Low Mass Steel Bolt Carrier Group (BCG) Q&A
Question - Can it run all three calibers listed? My main concern i
Cryptic
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AR 15 Parts
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AR15 Upper Parts
Cryptic AR15 Upper Parts
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Bolt Carrier Groups
Cryptic Bolt Carrier Groups
Cryptic .223 / 5.56 / .300 AAC Blackout Low Mass Steel Bolt Carrier Group (BCG)
Cryptic .223 / 5.56 / .300 AAC Blackout Low Mass Steel Bolt Carrier Group (BCG) Q&A
Question - Can it run all three calibers listed? My main concern i
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AR15 Upper Parts
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Bolt Carrier Groups
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Cryptic .223 / 5.56 / .300 AAC Blackout Low Mass Steel Bolt Carrier Group (BCG)
Cryptic .223 / 5.56 / .300 AAC Blackout Low Mass Steel Bolt Carrier Group (BCG) Q&A
Question - Can it run all three calibers listed? My main concern i
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Can it run all three calibers listed? My main concern is can I run 300aac if I were to purchase this exact BCG? — 1 Answer
by Alfonso, from TX, United States Asked on August 20, 2025
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Gun Parts
Cryptic Gun Parts
Cryptic .223 / 5.56 / .300 AAC Blackout Low Mass Steel Bolt Carrier Group (BCG)
Cryptic .223 / 5.56 / .300 AAC Blackout Low Mass Steel Bolt Carrier Group (BCG) Q&A
Question - Can it run all three calibers listed? My main concern i
Cryptic
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Gun Parts
Cryptic Gun Parts
+
AR 15 Parts
Cryptic AR15 Parts
+
AR15 Upper Parts
Cryptic AR15 Upper Parts
Cryptic .223 / 5.56 / .300 AAC Blackout Low Mass Steel Bolt Carrier Group (BCG)
Cryptic .223 / 5.56 / .300 AAC Blackout Low Mass Steel Bolt Carrier Group (BCG) Q&A
Question - Can it run all three calibers listed? My main concern i
Cryptic
+
Gun Parts
Cryptic Gun Parts
+
Rifle Parts
Cryptic Rifle Parts
+
AR 15 Parts
Cryptic AR15 Parts
+
AR15 Upper Parts
Cryptic AR15 Upper Parts
Cryptic .223 / 5.56 / .300 AAC Blackout Low Mass Steel Bolt Carrier Group (BCG)
Cryptic .223 / 5.56 / .300 AAC Blackout Low Mass Steel Bolt Carrier Group (BCG) Q&A
Question - Can it run all three calibers listed? My main concern i
Cryptic
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Gun Parts
Cryptic Gun Parts
+
AR 15 Parts
Cryptic AR15 Parts
Cryptic .223 / 5.56 / .300 AAC Blackout Low Mass Steel Bolt Carrier Group (BCG)
Cryptic .223 / 5.56 / .300 AAC Blackout Low Mass Steel Bolt Carrier Group (BCG) Q&A
Question - Can it run all three calibers listed? My main concern i
Cryptic
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Gun Parts
Cryptic Gun Parts
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Rifle Parts
Cryptic Rifle Parts
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AR 15 Parts
Cryptic AR15 Parts
Cryptic .223 / 5.56 / .300 AAC Blackout Low Mass Steel Bolt Carrier Group (BCG)
Cryptic .223 / 5.56 / .300 AAC Blackout Low Mass Steel Bolt Carrier Group (BCG) Q&A
Question - Can it run all three calibers listed? My main concern i
Cryptic
+
Gun Parts
Cryptic Gun Parts
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Rifle Parts
Cryptic Rifle Parts
Cryptic .223 / 5.56 / .300 AAC Blackout Low Mass Steel Bolt Carrier Group (BCG)
Cryptic .223 / 5.56 / .300 AAC Blackout Low Mass Steel Bolt Carrier Group (BCG) Q&A
Question - Can it run all three calibers listed? My main concern i
Cryptic
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Gun Parts
Cryptic Gun Parts
+
AR 15 Parts
Cryptic AR15 Parts
+
AR15 Upper Parts
Cryptic AR15 Upper Parts
+
Bolt Carrier Groups
Cryptic Bolt Carrier Groups
Cryptic .223 / 5.56 / .300 AAC Blackout Low Mass Steel Bolt Carrier Group (BCG)
Cryptic .223 / 5.56 / .300 AAC Blackout Low Mass Steel Bolt Carrier Group (BCG) Q&A
Question - Can it run all three calibers listed? My main concern i
Cryptic
+
Gun Parts
Cryptic Gun Parts
+
Rifle Parts
Cryptic Rifle Parts
+
AR 15 Parts
Cryptic AR15 Parts
+
AR15 Upper Parts
Cryptic AR15 Upper Parts
+
Bolt Carrier Groups
Cryptic Bolt Carrier Groups
Cryptic .223 / 5.56 / .300 AAC Blackout Low Mass Steel Bolt Carrier Group (BCG)
Cryptic .223 / 5.56 / .300 AAC Blackout Low Mass Steel Bolt Carrier Group (BCG) Q&A
Question - Can it run all three calibers listed? My main concern i
Last updated 2026-02-13 UTC.