Sidesaddle affects recoil operated shotguns?

[Hammerhead]

Hello,
It is common to hear that you should not put a Sidesaddle on a Benelli or any other recoil operated shotgun, because the added weight will affect the operation, but I can't figure that out.

Added weight should HELP a recoil operated shotgun, not interfere with its operation. The added weight will help steady the gun, just like holding it tightly to your shoulder.

To take it to the nth degree, think about bolting it to a '57 Chevy. The receiver AIN'T gonna move, so the bolt will have plenty of recoil energy to eject/shuck/close.

So, what am I missing? It is also part of "common knowledge" that if you tighten the Sidesaddle too much, it will pinch the receiver and cause a malfunction, so are all Sidesaddle-related malfunctions caused by too much screwing?... err, having the screws too tight?

Anyway, thanks in advance for the information.

Regards,
Hammerhead

 

[EJ]

Sidesaddle-related malfunctions caused by too much screwing

LMAO

 

[JJohnston015]

Ohh! Ohh! Call on me!

After finally figuring out how recoil (actually "inertia" operated - there's a difference) guns work, I've been dying for the chance to run my explanation up the flagpole to see if anybody salutes.

First off, the Benelli has a rotary locking bolt in a carrier, like the ARs and Winchester pump shotguns. They also have an "inertia spring" (I believe Benelli calls it) between the carrier and bolt, which gets compressed if the carrier is pushed forward from the closed position. You always see this spring in the cutaway view of the bolt/carrier assembly in Benelli ads.

Picture this setup: you've got something heavy, say an engine block (the carrier), in the bed of a truck (the gun). There's a short, heavy spring between the block and the front of the bed (the inertia spring). There's also a longer spring between the block and the tailgate, which will be compressed when the block moves toward the back (the recoil spring).

Put the truck into reverse and punch it. What happens? The block will tend not to move with the truck right away, and will seem to move forward relative to the bed, compressing the short, heavy spring. The same thing happens to the bolt carrier in the Benelli from the initial rearward recoil movement.

Then, about the time the block gets up to speed going backwards, slam on the brakes or back the truck into a wall. What happens? The block slides toward the back of the bed, due to its inertia and with some extra push from the compressed short spring. As it moves back, it compresses the longer spring. When it has stopped, the longer spring pushes it back to its starting position. The same thing happens with the gun when it hits your shoulder and stops suddenly: the carrier keeps moving backward, from inertia and with a boost from the inertia spring (unlocking and opening the the bolt as it does), then the recoil spring pushes it forward again.

As for adding weight (actually mass - the sidesaddle): weigh down the truck with cinderblocks and try again. What happens? It doesn't accelerate as fast, so it's not going as fast when you hit the wall; the block (or bolt carrier) won't be going as fast when it starts moving to the rear, and may not make it all the way to the back of the bed. Result? Failure to extract, failure to eject, failure to pick up the next round, etc.

What about shooting light loads? Pull the big Detroit V-8 out of the truck and put in a 4-banger. Same result: rearward acceleration is reduced, so the block (or carrier) may not make it all the way to the rear.

As for bolting the gun to a solid object so it doesn't move, this should explain why nothing will happen. The carrier never starts moving to the rear, because the gun never moves to the rear.

Think of the other extreme: fire the gun in space (with nothing backing it up). It won't work there, either, because although the gun moves to the rear OK, it never stops. Same result.

So how come we never hear about "limp shouldering" when Benellis malfunction?

Hope this helps.

Edited for typos.

 

[Hammerhead]

Wow, excellent explanation DJJ! I think I understand now.

That also explains why no one has been able to get the malfunction when firing from the hip. It actually helps to "limp shoulder" the shotgun. (Cool phrase by the way!)

Regards,
Hammerhead

 

[Kobun]

DJJ,
That was a briliant explanation!
I know that the Benelli has to move to cycle.
This is why, when shooting with trap loads, and a pistolgrip stock, I have to hold the gun very loosly.
If I hold onto the gun with trap loads, it won't cycle.

 

[CWL]

If you call Surefire and talk to one of the techs, they'll actually recommend that you DO NOT buy their Benelli fixed-forestock light system because it is too heavy & may cause FTF difficulties. They recommend that you bolt a light with a clamp instead.

I think that regular sidesaddle will be OK, but you may want to test with your loads to ensure operation.

 

[Badger Arms]

I was under the impression that installing the sidesaddle on a Benelli caused a distortion in the receiver, which is more flimsy than most American guns, and caused binding. Inertia systems are finicky and have no place in a serious gun. (waiting to be struck down by flamers ) I prefer a system that I can shuck myself. The 1100 and 11/87 seem to be more sensible and less likely to fail.

Question: If you hold a Benelli very loosely as in from the hip or letting your petite wife shoot it, will the gun function reliably?

 

[JJohnston015]

Are you asking me? I'm not even sure if my explanation is right. I'm still waiting for some confirmation. In fact, I don't even own a Benelli. All my shotguns are gas operated, pump, or side by side. However, I did take physics, and two plus two equals four, everywhere you go.

I have heard that overtightening the crossbolt on a sidesaddle can pinch the receiver together, and that could indeed cause binding, but that's a different problem than just adding the mass of the sidesaddle to the gun.

As for holding the gun loosely: in short, it depends. Two requirements have to be met for the gun to work (assuming my explanation is correct):

1. The gun has to reach a minimum rearward speed before it starts slowing down.

2. It must stop fast enough at the end, i.e., it must have some minimum rate of deceleration (think: what would happen if you applied the brakes of the truck gradually?).

You can help requirement #1 by keeping your loads hot and the gun light. #2 is trickier: the shoulder into which the gun recoils has to give enough to allow the gun to get up to speed, but solid enough to stop it quickly. If it's held very loosely, it will probably get going OK, but may not stop fast enough.

So you're right about them being finicky. I imagine the Benelli engineers tore their hair out tuning the weight of the gun & carrier, and getting the spring rates just right, so the gun would function most of the time, for most shooters, without beating itself (or the shooter) to pieces.

Do you have one? I was next to one for the duration of a 4-day shotgun class, and it seemed like it made a strange sound when it cycled. Most shotguns make a "shuck-shick" sound, even semis, but this one made kind of a "ker-plonk". Have you noticed that?

 

[Badger Arms]

No, I don't own a Benelli. In fact, I don't own one for the reasons stated above, that they have the potential to be finicky. I did have an 1100 at one time but sold it. I have no need for an automatic shotgun. I doubt I'll ever own a Benelli, but if the price is right?

Anyhow, to continue about the warping of the receiver... I did have a gun in which the receiver was warped, it was a REMINGTON 870!!!! To tell you the truth, I bought this gun figuring it was a lemon but I'd be able to fix it. When I first got the gun, it was nearly impossible to cycle as the bolt and carrier were binding something fierce. I troubleshot the problem by first using action blaster and thoroughly cleaning and lubing the receiver. Problem diminished, but didn't disappear. I then took to dehorning and lapping the action raceways, action bars, etc., etc. The problem decreased still more but was still there.

I noticed that the left side of the receiver was worn like it had been shot lots with a sidesaddle. When I looked at the other side of the receiver, I detected an ever-so-slight bowing of the surface. A straight-edge showed a deflection of about .025". I corrected the problem by inserting a bolt from the inside of the receiver and inserting a punch through the left side of the receiver. With the receiver setting on two wooden dowels at the front and rear, I whacked the punch in small increments until the receiver was straight. Reassembled gun and gun cycled perfectly. It was also MUCH smoother due to my trobleshooting process.

 

[HS/LD]

Badger do you mean to say that you had a problem with an 870?!?!?

Even worse it was the receiver that was the problem????

HS/LD

 

[Badger Arms]

That's a correct statement. Yes, it was a problem with the receiver. The gun isn't an icon, it's a gun. I did however, fix the problem without too much hassle. In fact, I love the gun now. I trust the gun now because I have gone through a complete function check and action honing. My gun, MINE!!!

 

[mpthole]

I've got an M1S90 and I think they do make a different sound than most other shotguns when firing. I've never had any problems with mine what-so-ever... no FTF or FTE. It just keeps going and going and going...

 

[redneck]

I don't know whole heck of a lot about how the gun works, but I'll throw out an alternative to the one already out there. Or maybe the same idea explained differently

Simple physics. Force = Mass X Acceleration
You need a certain force to move an abject a certain distance. That force is provided by the recoil energy of the gun being fired. Expanding gas pushes on bullet/shot load and gun an equal amount in opposite directions (equal and opposite reaction)
Now, the reason a heavier gun doesn't have as much felt recoil is that it has more mass, which means more force is required to get the same push (acceleration).
So if you add mass to the gun, it absorbs more recoil energy, which means less energy acts on the bolt.
Basically when you have enough energy to move everything backwards, you have enough energy to slam the bolt backwards. If all the energy is sucked up trying to move the gun backwards, the bolt won't go anywhere though.

 

[Matthew Courtney]

The 1100/1187 gas mechanism pushes the action back while pushing the rest of the gun forward. That is why there is less felt recoil. It is also why the 1100/1187 design is very reliable as long as you keep the gas mechanism clean.

 

[Hammerhead]

Hmmm. After reading all these excellent replies, now I am wondering if a REALLY big, strong, guy could cause a failure with a recoil-operated shotgun? Especially firing from prone position?

Interesting to think about...

Regards,
Hammerhead