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M4S90 vs. M1014 barrel extension flare/ring?


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Did we ever determine the "why" as to why this was added to the M4S90? Do current USMC issue M41014's have it? Picture evidence for yay or nay?


Anyone with a high-mile M1014 notice any abnormal wear in the receiver because it ISN'T there? Pix?


The 2000 circ USMC manual shows it clearly not being there:



This clearly shows it sans said collar, taken 2009:


This taken at Camp Pendleton, 2013, also clearly shows lack. This is entirely speculation, but the gun looks pretty "clean" to not be somewhat new:


Edited by Unobtanium
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Nothing definitive in writing. It seems like an inline upgrade. It does act as a visual indicator to determine if the barrel is fully seated. It does provide a larger seating area for the barrel. This could reduce harmonics of the barrel. There are further modifications to the barrel on the portion that enters the receiver. If I recall, the "wing" at the rear of the barrel was enlarged from the original model to the current production units.


I'll take some quality pictures of the 11707 mod barrel's inner receiver extension. If someone with a M1014 could take the same, we could show the design changes. Might take me a bit to post up since I'm out looking at a ranch to buy at the moment.


So others know what we're talking about when we mention the barrel ring, note the portion of the barrel just ahead of the receiver:


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Great photos VertigoFirearms!


After looking at the rear extended wing, it appears it is mainly to protect the aluminum receiver from ejecting shells. The barrel ring and larger wing also acts as a larger dead blow during recoil. Larger surface area for the barrel to recoil against the aluminum receiver.


Here are some shots I took:




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I would concur with it helping with recoil except that this goes against physics. Under recoil, the barrel will attempt to move FORWARD, not rearward. The shot charge will hit the forcing cone, pushing AGAINST the barrel. The recoil will knock the weapon as a whole backwards, and thus everything on it will be pushed forwards due to the laws of inertia. This is how the ID system in other Benelli's functions, as well as why every keyed mount should be pushed FORWARD in the 1913 rail slots on a weapon system.


As to a visual indicator, the USMC and civilian manual states "make sure no silver is showing". It doesn't get simpler than that.


Regarding harmonic stability, this is the only thing I can think of that makes sense based on the physics of the system. It well could damp vibration. The accuracy from my M1014 with slugs is stunning (1-hole groups at 25 yards, hitting torso-sized targets at 200 yards once I find my range, if I can "guess" where they are behind the HUGE fsp, lol). That said, this was why I was curious if anyone had a high-mileage M1014 that an inner-receiver picture could be taken of, to see if the harmonics are not as kind to it as the M4S90's.

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Well...that's that, then.


My point was it would have been a soup sammich if that actually was load-bearing, really, as only 1 load bearing surface should be used in a non-precision (Sorry, the M4 barrel/receiver interface isn't a precision piece of machinery by this definition) instrument. This prevents un-even load-bearing between the two. It appears it really is, just a stop.

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Yes both barrels fit. The issue is the handguard, M4 civilian handguard will fit into both barrels, but the M1014 will only fit its original. M1014 handguards are uncommon to find, and even then they are cheap to replace.


I put a M1014 barrel on my M4 and didn't notice anything out of the ordinary regarding the M4 handguards going back on.

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