Unobtanium

Correct. With irons in got zero difference in poi shift. With the receiver mounted optic, I got the shift. This furthers my opinion that barrel expansion is the cause, as if the barrel moved, the FS moved with it , compensating aim for the movement.

But only when hot , and immediately corrected by loosening and retightening the mag cap?

I am M4-less currently.

I did not. I will see what this SBS does. I am curious if anyone else would care to replicate my test with THEIR M1014/M4. It's easy enough, get 6 targets, place at 25 yards. You should be able to place a slug within 1/2" of POA at this distance on demand from the prong over a bag. Shoot all 6 bulls rapidly, see where shot #6 ends up... They make a "6 bull" target and sell it at most stores. If not, I am sure it could be improved, fire 1 round on target, 5 into the dirt, 1 round on target, see where the two are in relation, etc.

I am not saying it did. I do know that after 6 rounds , I had a 12moa shift to 6 o clock. This went away once the weapon cooled...or immediately , if I loosened and retightened the retaining cap, which was tighter than originally, indicating that the barrel had elongated and tension was being applied to the barrel hanger in greater amount. Would the steel mag tube grow at the same rate as the barrel? Doubtful. It doesn't get as hot as fast. Still a curious test.

Well, like in said initially, there were several reasons for my choice. Eliminating that variable is one of them. I would need to do more testing to see if the mag tube contributed. My gut says no, but it IS a variable beyond the configuration the military tested. Ti is very good for high heat areas as you state, but coefficients of expansion must Play Well together. Remember the days of iron blocks and aluminum heads? Again, not saying the tube caused it, just saying it's a variable in play, and at the reduced length of the 5 shot tube , it's not worth messing with, as you state, imo

I am not saying it was the mag tube. I am saying it could have been. Was It? No, I'd need more data. Was it me? No. I was stacking them. I of course thought I was to blame, so I benched the gun and tested as such at 25 yards. At 25 yards, from a sandbag, there is no way this user was to blame. Ymmv. Here is a 50 yard group from a sandbag fired using my benelli supernova as proof of capability. 3 rounds.

A deer no, but pigs yes. I just used deer as an example. In a mere 6 rounds, I was hitting 12moa low. You can easily fire 6 rounds at some hogs in some areas. Or just target shooting etc. It shocked me to be honest. Now, I doubt enough heat is transmitted to the mag tube to matter, but I am curious to see, and I do note that the milspec m1014 passed all testing , and it would seem a concern I would think if it exhibited this much shift that fast, but maybe not. I need more data.

Out to 50 yards using irons I shoot sub moa. Further, I have tracked 12moa + shifts due to thermal barrel expansion vs. mag tube etc. It's not as mundane as your like to make it when it can cause. Complete miss of a deer kill zone at 100 yards.

Weight closer to the shooter matters less. With the 7 shot tube, you also add 4oz or so of shells past the 5 shot tube, making weight savings a bigger deal. You are correct on longer tube being more critical regarding rigidity. Also same on heat transfer. However, recent experiences have led me to preferring the milspec tube, it just hurts a lot less in the weight dept. On the sbs.

The 5 shot tube is shorter than the 7 shot tube, so less weight to be saved. Also, it's closer to the shooter. Steel is 200% stiffer than Ti. Also, the barrel is steel. Coefficient of expansion is much less in Ti than steel. The mag tube stabilizes the barrel. I want it to expand and contract the same as the barrel with heat, and be as rigid as possible, as the weight savings of going Ti aren't really worth it to me on this setup.

However, were you to SBS the Benelli M4 to a 14" gun, you could add the 12" barrel later to your collection and legally use it, as it is still an SBS. The BATFE REQUESTS that you inform them if you PERMANENTLY change it (say you sell your 14" barrel and the only configuration you possess is the 12")

Exactly. I didn't want the receiver messed with, etc. Also, "factory SBS" is just CDI points.

Showing 3 available, better get yours fast.

Apparently so was my X gf. Now guess who's single That said, you can buy an OEM Benelli M4 SBS barrel assembly here: https://www.benelliparts.net/store/p6/Benelli_M4_14"_SBS_Short_Barrel.html

I thought about running a suppressor, but decided against it. Shotguns are low-pressure, and while loud, less likely to absolutely screw hearing than say, a rifle or .357 mag, and a can will only knock it down into the high 130's, and it weighs about 2#. I am also keeping the OEM mag tube. I thought about going the Ti route, but thermal expansion properties and elasticity modulus on this component outweighed the benefits of lighter, in this application for me.

Interesting barrel/muzzle profile. Mine is cut flat across, and on the transition of the ID to the flat "face" of the barrel, has a 45* angle chamfer about 1/4mm long (yes, microscopic nearly, they broke the edge is it). The flat is finished, not bare. When was your barrel made?

I do have friends in the NFA branch, but not on the approvals side of things. Investigative. I've come to the conclusion that I have friends pretty much everywhere. Except there. Those people don't have friends

Thanks! I know going from 18.5" to a 14" barrel doesn't sound like a lot "on paper", but just moving from low ready to target, and handling the weapon in general...it's literally like comparing my SUV now to the Z06 corvette I used to have. Yeah, they weigh similar (CX5, couldn't get 100% away from sportiness, even if I needed AWD and practicality) and have 4 tires...but damn! I installed a TTI black safety, and it is now my favorite of the breed. I am waiting until I take it home to install the Surefire/IWC combo and the H2/Scalarworks combo, but this thing is awesome. Oh, and the barrel is re-finished where they chopped it. NOT bare metal. The shop said they have seen this on more recent SBS M4's (circa polymer trigger-guard). I however already dropped in my OEM metal one that I bought from a poster here, earlier. SO it's G2G

The most expensive empty box to ever ride in my vehicle.

Kinda sorta not exactly. A&S has copied benelli critical dimensions...but How? Did they call and get the tdp? Doubtful. My guess is that they got a few and modeled them up. But were those on the small or large end, and will A&S be able to keep their tolerances so small that this is fine , or did they copy the tightest 10% and do they have 15% in variance of their own , while benelli has the tdp, and shoots their say, 20% variance right down the middle, ensuring that x percent of A&S parts are outside the spec? We dunno... ...welcome to ar15s, circa 1990!

There's a free surgery that can help with that. They offer it for 922r violators, free of charge!

Just got done paying for an 11724 that had the polymer fcg. It is so difficult to cock with safety on that I didn't try harder. I guess with enough force it could be... The vary. Ymmv. It has been and is normal.

1998ish or so

The main issue is off-axis weight. Keep it less than OEM, and you're G2G. Don't forget though that the bolt-handle does endure a lot of stress. The GG&G larger ones were actually bending back in the day. Part of the issue with the bolt-handle is that when you enlarge the tactile portion's diameter, and enhance its gripping surface, you allow more rotational force to be transmitted as the weapon is charged. This rotational force causes the CH to want to turn, and it can lead to losing the CH in the dirt/forever. I had an original Carrier Comp Black CH that would do this. Fit was flawless, it was just physics. If you got aggressive with it, it could and would happen. I personally just run the OEM CH. If Kip were to do another run, I'd buy it "because", but that's my .02 on it.