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Benelli M4 cycling. Does it get better?


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The 4 port barrels do cycle light loads better. However as benelli said over thousands of heavy max loads it beats up the receiver/bolt. Since the gun is designed for heavy loads they switched to a 2 port design which lets less gas through, slowing the bolt reducing receiver/bolt impact with super heavy loads but not impacting reliability with those loads. The result however with super light loads is it does not cycle them as well.


Best bet is as others have said, polish all the surfaces you can, clean it very well, and use a light oil on it.

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How light of a load do you want to shoot? Your M4 should handle weak valuepack ammunition. I've even ran a few boxes of handicapt loads through the M4 just to try it. Determine what type of jam is occurring. A weak recoil spring will often leave the bolt carrier hanging up to the rear.


Through trial and error, a lighter bolt handle has shown to increase cyclic rates and reliability. Try removing the bolt handle when testing the weapon to see if there is any benefit.


Use a quality oil. Something like Machinegunners lube that LaRue sells. The M4 wants to run relatively wet. If it still continues to cycle poorly, there is a problem with that weapon.

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Most important things for a Benelli M4 to cycle light ammo in my experience and what I've seen on these boards.


1. Lube action generously.

2. Keep the stock securely seated when shooting. (not sure if this is true since the M4 is supposed to cycle from the gas piston system, but one person I've shot with couldn't get it to cycle properly occasionally, where I had no problems on the same outing.

3. Lube action generously.

4. It might need a break in period. (preferably with heavier ammo)

5. Lube action generously.


There is a big difference in most Benelli shotguns and the Benelli M4. The military didn't want to depend on inertia for cycling the loads, so they insisted that the shotgun have a gas system. That's why many say you can't hang a bunch of accessories on an Benelli M2 and other shotguns in their semi-auto line and expect it to cycle correctly.

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I just purchased a used Benelli M1 (20 gauge). Not the same gun but the lesson may be the same.

The gun would not chamber the shells reliably. When the bolt was locked back and I "hit the button" the bolt would not always go into a locked position.


I tore the thing apart and cleaned the dickens out of the recoil spring area, bolt receiver etc. I lightly lubed with RemOil and reassembled. It seemed to work a bit better but was still not reliable. I finally tore apart the magazine and cleaned and lubed everything. THAT was the issue. The follower was all gummed up and dirty and the magazine spring could not force the shells onto the carrier easily. I typically do not (or didn't ;)) clean my magazine assembly. Just another area to look at and make sure it is clean and working properly.


BTW I am looking to replace the recoil and magazine springs to make sure the gun is reliable as it is intended to be my chukar gun and I DO NOT want to be fiddling with the thing when the birds are a flyin.



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I second the heavy wet lube on the entire bolt carrier assembly - dripping wet.


I assume your trying to shoot 2.5 dram loads?


What I would do is save a bunch of your powder-puff #7 boxes and fill them with 3.25 dram #6 Federal ($4 for 25 at Walmart) and take that to the range. That will cycle 100%


This conversation reminds me why I love New Mexico - I can drive 20 minutes out into the desert and do WHATEVER I WANT. Haven't been to a range in a long time, and I don't like them.

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I'll add one more thought to this...if your gun DOES shoot the light load stuff, you might have a slightly weaker spring from the factory that may subject your gun to more battering when you shoot the kinds of loads the M4 was intended to shoot. Just sayin.


I figured the M4 had an automatically adjusting gas system so it could cycle light loads and heavy loads both without there being any issues like this.

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The m4 usually fails as a result of the spring being weak, but not in the way most think. Usually it will cycle to the rear, but the spring doesn't have the balls to load the new shell into battery. It gets hung up as the bolt rides the hammer near the rear of the cycle. A tap on the bolt handle will feed the round. If this is the case, it's time for a new factory spring. They're cheap.


A brand new "stiff" spring should cycle down to Micky mouse value pack crap reliably. I've installed brand new springs and entirely new recoil tubes. The end game is the same.

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Out of stock at the moment. Put a few on back order and play the waiting game. Wolff does not make a replacement unfortunately. They have a few that will fit, but I wouldn't recommend them. They're 25% extra power and 25% reduced power springs. You gain little by messing with the spring strength IMO.


The Wolff ones aren't meant to be used in the M4. They will say they are meant for all the Super90 series. I tried an extra power one, and it was only about 90% reliable with cheap value pack ammunition. High brass fired just fine, but I felt no benefit from running the heavier spring.


Kip, if you're reading this. Have you ever tried to light a fire under Wolff to get them to build a dedicated spring for the M4? I know you have an in with them with the magazine tube springs.

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