The AR-18/180, the AK series, and the M-240, M-249, M-60's bolt system runs on a type of a rail to prevent it from carrier tilt. These new ones for the 15 series do not.
This is where they run into problems.
1. Uneven wear or scaring the bottom of the receiver extension tube as the op rod pushes the top of the BCG, the bottom rubs against the receiver extension tube.
2. More moving parts and springs.
On the same line with carrier tilt.
3. If the carrier tilts enough before it comes out of battery, it does have the possibility to break the bolt at it's weakest point. The cam pin hole. That is where the walls are the thinnest.
on a side note...
4. It is claimed to run cleaner...
FALSE ... It just relocates the carbon to a different location (under the handguard). You still have to clean it. If you do happen to run it suppressed, it still put the residue in the receiver.
Good info thank you. I just regret selling my AR 180 back in 1988! I still think there could be a market for an updated one, although I know Armalite tried before.
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