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M2 Inertia System -Can I Mount A Light?


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I've been searching the forums and am confused with trying to find a mount and light for my new M2. My gun store sold me a LaserLyte magazine tube mount to mount a Streamlite TRL1S but this round mount is too small and would not go on the magazine tube. Searching around the internet seems like everything is for the M4.

 

I read on another forum that due to the inertia system the M2 uses that I shouldn't mount a light to the M2 or even think about adding a magazine extension.

 

1st post here...this Benelli M2 is my 1st shotgun so I am very new at this. Thanks in advance for any help.

 

Mike

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Hi mdrums and welcome to the forum! Surefire makes some very nice light integrated forearms for the M2

 

http://www.surefire.com/illumination/weaponlights/shotgun-forend/benellisuper90snabovem104800.html

 

beyond that the more weight you add (sidesaddles etc) the more the chance you may have cycling issues but as long as you stick to high power loads you can probably get away with the light and an extension. I have an extension on my M1 and have never had an issue

 

Later,

 

Hookster :)

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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.

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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.

 

Hi this is very insightful but I am curious to know where you got this information from. Or is this just from your personal experience? Thanks.

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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.

Edited by benelliwerkes
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Wow...my head hurts!

 

Well, maybe I bought the wrong gun and should have stuck with the Mossberg I was going to get that already had a light on it...plus it was only $489. Ouch..buyers remorse begins...my own fault, I didn't do my research like I usually do and got wrapped up and bought the Bennelli M2 thinking it was a reliable cool gun...guess I was totally wrong.

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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.

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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.

 

What does fully-loaded mean? That can vary by over half a pound comparing the neutered version of the M1/M2's to the full-length tubed M1/M2's, no?

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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.

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I met a guy at a local gun shop that has a M2 and he put on the Nordic +3 extension tube and Light Rail...zero issues with the gun and these accessories. PERFECT!

 

Check out the M2 3-gun model video posted by M1014...If they are running X-rails reliably I'm sure you can get away with your extension and light

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I've got a light (SF X300) and a custom 6 shot carrier (on the stock), and it works like a champ. I also tried firing it with the butt stock up against a tree (just 'cus I heard all the rumors about that) and it still functioned flawlessly. I mostly use 2 3/4" Federal LE 9 pel flight control or the true ball slugs, including some low recoil ones. I say try it and see, but that's just me.

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Thanks everyone for the reply's.

 

I think I'm going to order the +3 Nordic tub extension and their rail and a Sure Fire light with the on off ton I can place on the forearm.

 

I jut learned about the X-Rail and watched some video's on it...wow that thing is cool. If a M2 can shoot just fine with it and little light and +3 tube extension will not matter.

 

Thansl again for all the reply's!

 

Mike

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