benelliwerkes

Here are some......if you had the Benelli M4 Anatomy Series Manual you would have such photos ! [ATTACH=CONFIG]1469[/ATTACH][ATTACH=CONFIG]1470[/ATTACH]

The information on the other forum was wrong !

I don't know if Benelli's "lowest level of kinetic energy that must be generated by the cartridge" (as stated in their manuals) was for the standard or higher capacity magazine model. My assumption, is that if Benelli was going to offer 2 models, they would design the bolt weight and know which cartridge energy was required for the heavier of the two models to function correctly. My only point being, is that adding optional equipment to the system, such that the bolt weight / total gun weight differential begins to exceed that engineered for the model's inertia bolt weight, reliability of the cycling action can be anticipated in these styled actions.

The inertia bolt systems require the gun to move relative to the bolt; so adding too much weight to the gun does not allow the gun to instantaneously move rearward sufficiently, relative to the bolt, for the action to cycle properly. In addition to weight, firing the gun held in a rigid bench rest may also cause the action to not cycle, for the same reason, the gun cannot move rearward instantaneously about the stationary "inertia" bolt, which compresses the bolt spring which drives the bolt rearward. A tactical situation that can almost replicate this, is firing the rigidly held gun with your back to a wall, the gun cannot move rearward relative to the bolt. When the gun buttstock is on the ground and fired, the same situation may occur. The M4 ERGO system, eliminates all these physics related issues that might occur with an inertia based action system.

From the Benelli M1 Manual: Extensive testing in ballistics labs and repeated field-testing of our line produced weapons put at 180 kgm the lowest level of kinetic energy that must be generated by the cartridge 12 gauge and at 125 kgm for 20 gauge to fully cycle the action (the measurement was taken on a manometric barrel, according to at a velocity of V1 at 10 meter distance from the muzzle). Empirically, Benelli has determined the minimum threshold of kinetic energy required to cycle the bolt; the rest of the understanding is simple mathematics / physics. Simple kinetic energy relationships will assist in understanding the rest of the story. KEMin = ½ m VMin2 KE=kinetic energy m=mass of gun V1 = Vmin = minimum cartridge power to cycle M1 action as derived by Benelli's empiric observation noted in the manuals. V 1 = √ 2 * KEMin / m1 When the mass of the gun is increased = m2 ; V2 will be LESS than V1 V 2 = √ 2 * KEMin / m2 Because V2 is less than V1, the minimum amount of kinetic energy to cycle the inertia bolt mechanism is not generated. The Benelli M1 20 gauge inertia bolt weighs 385 grams. Two 20 gauge cartridges weigh 65 grams Two shot magazine tube extension weighs 300 grams Total = 365 grams So, a 2 shot extension tube with cartridges is within 20 grams (2/3 of ounce) weight of the inertia bolt weight. The attached may assist in understanding how adding weight / mass to the inertia platform may interfere with reliable cycling operation. The 20 gauge M1 bolt weighs 385 grams; a 2 shot magazine tube extension weighs 300 grams Plus 65 grams for the 2 cartridges and you have 365 grams of extra weight; almost the weight of the bolt. Third parties cite Benelli sources as stating that ~ 500 grams of added weight (1.1 pounds) begins to reduce reliable function. A 12 gauge 2 shot extension and two 3" cartridges is just about 500 grams......again, just about the mass of the 12 gauge inertia bolt. So, the addition of the 2-shot extensions plus the cartridges do not exceed the bolt weight, but add a Picatinny rail and a light etc......therein the problems of operation may begin to be experienced.

A rough guide for adding weight above and beyond a fully loaded weapon for the inertia cycled Benelli bolts is 20 gauge : less than 385 grams and you should be okay 12 gauge: less than 500 grams and you should be okay These are the approximate weights of the bolts; when the weight added to the gun exceeds the bolt weight, you may begin to experience cycling problems with the inertia system.

Sounds like yours is working fine. The M4 has several different loaded status configurations. The Anatomy Series Benelli M4 Manual explains and illustrates all these things.

If you find yourself needing to apply strap wrenches to the magazine tube, or support the magazine tube in a vise you should consider supporting the inside of the tube to maintain its internal diameter; even the slightest deformation / indentation will prevent the cartridges from feeding properly. Place the largest socket wrench, usually a deep socket style) diameter that will fit inside the tube and only secure the magazine segment in a vise that is so supported. (a hard wood dowel also will work). As, necessary, applying a few winds of painters tape to the outside of the socket wrench will allow you to best fit the support to the inside tube diameter; you want the support to a few thousandths larger than the cartridge rim. To protect the outside of the tube and prevent it from spinning about in the vise, wrap the magazine in 1-2 layers of non-skid tool drawer liner......the soft rubber perforator style works well.

I could have sworn the inquiry was "WHY" not "HOW". As for how you do it in a chrome lined barrel, it's the same method, you just have to be prepared to pay extra to have your barrel re-chromed ($50-$250), get it Cryo stress relieved, or just use a honing stone and polish the forcing cone segment that was relieved to a mirror finish. The chrome lining is more corrosion resistant and a little easier to clean, but otherwise there is nothing sacred about chrome surface per se that will alter performance.

Modifying the forcing cone, by polishing and extending the length of the barrel "cone" it allows a more gentle constriction of the shot pellets to be shaped into their pattern, usually something like a 5 degree angle of constriction immediately in front of the chamber to a 2-3 degree angle of constriction (over the longer length); the result is generally a more consistent shot pattern and some claim a measurable reduction in felt recoil as well. AimPro Tactical specializes in performing this service on Mossberg 590's.

This setup is for Bello..... for when the operator enters the front door, but the bad guy has scampered a few hundred yards out the back door!!!.....the best part, it does fit in the kitchen sink. [ATTACH=CONFIG]1418[/ATTACH][ATTACH=CONFIG]1417[/ATTACH]

Wrap the bronze / brass brush in #3 / #4 - OOOO steel wool, and then chuck the brass rod securing the brush into a hand held variable speed drill......low speed, multiple passes will usually make the bore sparkle.

I agree with the notion of difficulty aiming these these beyond close quarters contact range......they look menacing, but it is not my first choice from the under the bed. [ATTACH=CONFIG]1409[/ATTACH]

[ATTACH=CONFIG]1402[/ATTACH]Not nose heavy when you cut the noses off.[ATTACH=CONFIG]1401[/ATTACH][ATTACH=CONFIG]1400[/ATTACH]

What KFab said. [ATTACH=CONFIG]1395[/ATTACH]

I have installed several of them. The Mesa part must be modified to be installed on the M4. As a general rule.....ALWAYS modify the least expensive part or the part that is most readily replaceable. In this case, do NOT modify your buttstock pin aperture; rather, reduce the external diameter of the 2-part "screw" from Mesa that replaces the OEM roll pin. You can chuck the 2 part screw in a drill press / lathe and use a file to reduce the diameter; go slow and trial fit the parts. See attached. [ATTACH=CONFIG]1389[/ATTACH][ATTACH=CONFIG]1387[/ATTACH][ATTACH=CONFIG]1388[/ATTACH]

I think the photos might depict "installed in the USA".

1:28" right hand twist.

[ATTACH=CONFIG]1321[/ATTACH] Normal tab has about a 85 degree angle.

AHA. The old magnet trick works again. All the trigger group components are steel except the carrier which is a light weight non-ferrous alloy. I was studying your photo.....it almost appears that the action lever tab that engages the hammer spring cap, is bent to less than 90 degrees ? parallax, or is it really turned inward ?

does the "aluminum" hammer spring cap pass the magnet test ?

Email your request to [email protected] and I will forward the information to you. Thanks for your interest.

These photos might help. Having your own Anatomy Series Benelli M4 Super90 Manual would answer all these questions ! [ATTACH=CONFIG]1305[/ATTACH][ATTACH=CONFIG]1306[/ATTACH][ATTACH=CONFIG]1307[/ATTACH]

The Super90 "M" trigger-disconnector group is pretty simple to disassemble.....however if you have two thumbs you may find it a bit challenging due to the small disconnector pin......removal is fairly easy, re-installing it a bit tricky. These photos might help[ATTACH=CONFIG]1261[/ATTACH][ATTACH=CONFIG]1262[/ATTACH][ATTACH=CONFIG]1263[/ATTACH][ATTACH=CONFIG]1264[/ATTACH][ATTACH=CONFIG]1265[/ATTACH]

I keep several options close at hand......the PDX patterns pretty well, however down range you have to remember those 3 pellets are veering off in 3 different directions than the slug which may cause some unintended collateral misery. [ATTACH=CONFIG]1249[/ATTACH]