rattly inertial semi-auto

[jjohnwm]

I have a Beretta 1201F 3-inch 12-gauge semi-auto that I purchased near the end of the previous millennium. It's in excellent cosmetic shape, has not hunted or competed, but has had probably a couple or three thousand rounds through it just playing and plinking. I love it and shoot it a lot. Over the years its gotten smoother and smoother, and now cycles just about any load except some brands of superlight target stuff. It's bone-stock except for an aftermarket operating handle, and a recently-added (i.e. yesterday!) Speedfeed pistol-grip stock.

But, while trying it out after the stock swap, I noticed a slight rattling sound that seems to come from the rear receiver area when the gun is tipped forward and backward. It occurs only when the bolt is locked back; bolt forward, either cocked or after pulling the trigger, and there's no rattle. I actually removed the stock again and snooped around inside for a cause, but there's nothing visible. The noise is still there if the gun is manipulated and cycled with the stock removed.

I'm not really worried, because I looked at my only other semi-auto shotgun, a Super Vinci with only a couple hundred rounds fired, and damned if it doesn't make the same sound at the same times!

I've literally never noticed this before. In checking all over the internet, I see responses ranging from "They all do that!" to "Don't shoot it, you'll die!" Several shotgun "experts" have suggested it's the gas piston...strange answer considering that they are both inertial guns...

It's gnawing at me; what is it?

 

[kamlooky]

Plug in the mag tube?
Also known as a mag tube restrictor?

 

[Suther]

Plug in the mag tube?
Also known as a mag tube restrictor?

Rear of the receiver seems like an odd place for a magazine plug? Lol

 

[jjohnwm]

Plug in the mag tube?
Also known as a mag tube restrictor?

Nope; 5-round mag, no plug, no hunting for the 1201; Super Vinci is 3 rounds, never even checked to see if it's plugged.

Rear of the receiver seems like an odd place for a magazine plug? Lol

Yeah, the sound definitely comes from the rear receiver area.

 

[Suther]

Nope; 5-round mag, no removable plug, no hunting!






Yeah, the sound definitely comes from the rear receiver area.

Is there a recoil spring back there? Actually, if it only happens when the bolt is locked back maybe the bolt itself is making the noise?

 

[Buck1950]

Firing pin rattle, like an SKS ?

 

[jjohnwm]

Is there a recoil spring back there? Actually, if it only happens when the bolt is locked back maybe the bolt itself is making the noise?

There's a recoil spring inside the tube that projects back into the buttstock, but it's partially compressed even when the bolt is forward; and the sound only appears when the bolt is locked backward, i.e. when that spring is further compressed. There's no way it's rattling.

The bolt itself? I dunno...maybe? The 1201 has always been a fair-weather gun for me, a toy really. Cleaning has been fairly superficial, and it's never even been exposed to rain. That's another reason why I prefer the inertial action to a gas gun...it shoots so clean it's delightful.

I think I may have to do a complete tear-down and really go over everything. The last time I did that with a semi-auto shotgun...another 1201F that I owned years ago...I had to go online for help in re-assembling the thing.

 

[Grain]

Firing pin rattle, like an SKS ?

Could be the firing pin sliding back and forth, as the bolt head is fully forward, and may leave enough room for the firing pin spring to not be holding it firm until closed.

 

[RRH.01]

Not a beretta but similar operating system and same thing, tilt back and forth and there’s an audible click from the hammer.

Edit fixed the sound.

 

[guntech]

It's working fine... don't fix what isn't broken.

 

[jjohnwm]

Firing pin rattle, like an SKS ?

Lol, I read that and then went and shook my SKS...and, as expected, the whole dang thing rattles. The clicking from the receiver area on my SKS is there whether the bolt is locked back, locked into battery or after the trigger is pulled. I don't get that either...but it's an SKS so I kinda expect it and sorta don't give a crap.

Could be the firing pin sliding back and forth, as the bolt head is fully forward, and may leave enough room for the firing pin spring to not be holding it firm until closed.

Maybe I am misunderstanding this comment ^...the sound occurs only when the bolt is locked backwards on the 1202F, not when the bolt is forward, either before or after the trigger is pulled.

 

[Grain]

The 1202F has a rotating bolt head like Benelli inertia guns I believe. So if the bolt is locked back, the rotating bolt is not under pressure, is fully extended, so could allow the firing pin to have some play in the bolt if the firing pin spring is slightly tired.

Edit : If you rest your finger on the front of the rotating bolt when tipping back and forth, feel anything?

 

[jjohnwm]

Not a beretta but similar operating system and same click, on mine it’s the hammer when the bolt forward. Here’s a video, the sounds blown out for some reason but in person it’s a very audible click/tick sound

Yeah, my hammer is visible but is absolutely not flopping around loose like that.

The 1202F has a rotating bolt head like Benelli inertia guns I believe. So if the bolt is locked back, the rotating bolt is not under pressure, is fully extended, so could allow the firing pin to have some play in the bolt if the firing pin spring is slightly tired.

Yes, apparently the system on this gun is a predecessor to the Benelli M1 Super90. I get what you mean now, the bolt head itself is untensioned even with the bolt back. I think this is the answer.

It's working fine... don't fix what isn't broken.

Thanks for #####-slapping me back to the real world. I do have a tendency to "improve" things right into a non-functional state. But I should have perhaps mentioned right at the outset that the gun functions flawlessly, so I'm just gonna keep enjoying it and leave well-enough alone.

Don't even get me going on my misadventures when I got my very first Marlin levergun back in the 80's..."Hey, this trigger surely isn't supposed to flop back and forth so loosely; I bet I can fix it!"

Thanks to all for your comments and thoughts.

 

[RRH.01]

Yeah, my hammer is visible but is absolutely no flopping around loose like that.




Yes, apparently the system on this gun is a predecessor to the Benelli M1 Super90. I get what you mean now, the bolt head itself is untensioned even with the bolt back. I think this is the answer.




Thanks for #####-slapping me back to the real world. I do have a tendency to "improve" things right into a non-functional state. But I should have perhaps mentioned right at the outset that the gun functions flawlessly, so I'm just gonna keep enjoying it and leave well-enough alone.

Don't even get me going on my misadventures when I got my very first Marlin levergun back in the 80's..."Hey, this trigger surely isn't supposed to flop back and forth so loosely; I bet I can fix it!"

Thanks to all for your comments and thoughts.

Got ya, I see now I misread your post as far as where the bolt was when you hear the click