Chamber should stay closed . . . right?

Prof Young · November 29, 2021, 09:51 AM

I have a Winchester 1300 12ga. It's a pump, of course. When I fire it, the chamber comes part way open. That should not happen, right? When you shoot a pump shotgun the chamber should stay closed until you pump it, right? It's been doing this for a while but it didn't click in my brain until yesterday that something is wrong. Help?

Prof Young

FITASC · November 29, 2021, 09:59 AM

Sounds like you are possibly pulling back on the pump fore end while firing?

Prof Young · November 29, 2021, 10:12 AM

Yeah I thought of that, but if I don't even have my support hand on the pump it still happens.

Prof Young

Virginian · November 29, 2021, 10:18 AM

Perfectly normal. When you fire it it unlocks the pump mechanism. The swelling of the shell under pressure and recoil keeps the chamber closed until well after the ejecta is long gone out of the barrel. Most pumps do the same thing, but Winchester touted the fact theirs did it faster. If I shoot my Wingmaster one handed it will eject the empty shell.

mehavey · November 29, 2021, 12:05 PM

Quote:

Perfectly normal. When you fire it it unlocks the pump mechanism.

^^^^ THIS ^^^^

Pahoo · November 29, 2021, 12:21 PM

Quote:

It's a pump, of course. When I fire it, the chamber comes part way open. That should not happen, right?

Partway really has to be defined and if it's clearly noticeable, than for what ever reason, it's not normal. I have the same model and even though I understand that this is how it operates, I am have never noticed it. Keep working with it and see if the problem, goes away.....

Be Safe !!!

**44 AMP** · November 29, 2021, 12:57 PM

Clean the gun make sure there is no crud built up where the bolt locks, then
Fire the gun without your hand on the forearm (so there can be no question of you opening it) if the action opens, on its own, it needs work.

mehavey · November 29, 2021, 02:25 PM

If the shooter has a normal forearm hold, that hold is in slight tension.
When the action unlocks upon firing, that tension will naturally open the (now) unlocked action and pre-initiate the slide moving backward.

It's one of the reasons that pump actions can be so incredibly fast.

stagpanther · November 29, 2021, 02:36 PM

Interesting...my 870 never does that, even when I fire large magnums--does that mean something is wrong with it?

mehavey · November 29, 2021, 05:21 PM

Took the tightest of the three 870's out tonite -- the ATAC.
Ran light 3/4-oz skeet loads

two loads with forearm hold -- it opened upon firing/unlock
one with no forearm hold -- it was already unlocked/cracked open when I took hold of it again.

Sharkbite · November 29, 2021, 05:27 PM

That is not unusual at all. Most pump guns unlock when you press the trigger. Then the recoil hits the bolt and trys to shove it to the rear. Sometimes that force is enough to move the fore-end/ bolt slightly open.

jmr40 · November 29, 2021, 07:50 PM

Winchester used to advertise that as a feature to make them faster to operate. They called them the "Speed Pump".

http://looserounds.com/2020/07/13/th...otten-shotgun/

Quote:

Winchester always claimed that the 1300, which they nicknamed the “Speed Pump” was a faster design than what Remington and Mossberg offered in their designs, and I can actually agree. According to the manual; after the shotgun is fired, the locking lugs of the rotary bolt begin disengaging from the barrel extension and the recoil forces assist the slide in moving rearward. You can actually see this when you hold up a empty unloaded Model 1300 muzzle up. The shotgun unlock itself.

In my experience the feature works as advertised, but I don't think it actually made it faster to operate the action. In the end how fast you work the action comes down to how smooth everything operates. While the 1300 got a head start, I could never work the action any faster than an 870

**44 AMP** · November 29, 2021, 09:08 PM

OK,so newer shotguns are supposed to work that way, I guess. I know for a fact that the Winchester Model 12 does not.

ITs action remains firmly locked shut after the trigger is pulled, UNTIL you put some FORWARD pressure on the forearm. THEN it unlocks. Most of the time, the forward bump needed is supplied by a firm hold on the forearm, during recoil, Most model 12 shooters learn early on that you don't pull back on the forend when shooting you push forward until after the shot.

The model 12 can be fired as fast as you can pump it, if its one of the originals without a trigger disconnector. Done that, too!

the Rem 870 works a bit differently is slicker feeling, and of course has a disconnector.

I don't have personal experience with the Win 1300 but if it was based on the Win 1200 its inferior to the Rem 870. In my opinion.

mehavey · November 29, 2021, 10:27 PM

Notwithstanding my 870 post op cit, take a look at these three:
https://thefiringline.com/forums/sho...7&postcount=11
https://thefiringline.com/forums/sho...3&postcount=12
https://thefiringline.com/forums/sho...9&postcount=13

Shucking forward does seem to unlock stuck brass.

Jim Watson · November 30, 2021, 07:12 PM

Gough Thomas once clamped weights to the foreend of an Ithaca 37 and shot it without holding the foreend. When he got the weights right, it kicked itself open and ejected the empty.

mehavey · November 30, 2021, 08:54 PM

Quote:

fact that the Winchester Model 12 does not [open]...

Now you're gonna make me take my Model-12s out...

jmr40 · November 30, 2021, 09:46 PM

Quote:

OK,so newer shotguns are supposed to work that way, I guess. I know for a fact that the Winchester Model 12 does not.

Not all newer shotguns. To my knowledge only the 1300 with the rotary bolt. And I'm not even sure if all of them have the rotary bolt. The current production 1300's are made somewhere overseas and I don't know if they are even the same gun. I've not handled one in years.

The 870 and most others that I've used do not, but once well broken in most of those will unlock and cycle plenty fast.

The Happy kaboomer · November 30, 2021, 10:00 PM

It is normal. I shot a 1200 & 1300 for many years. It only unlocks AFTER the shot charge is gone. So no big deal. It will help you pump it faster........Don't worry.......Go shoot!

Virginian · December 1, 2021, 07:03 AM

The Winchester Model 12 was designed so that after the hammer drops the fore end must move forward slightly before it will come back. When a round is fired recoil takes care of that.
In reading over this it would appear a lot of people do not understand the basic physics that govern operation. A.22LR or a 9mm semi auto basically operate as blowback designs, consider that. BTW, neither design loses velocity versus a fixed breech design.

Jim Watson · December 1, 2021, 10:02 AM

Quote:

A.22LR or a 9mm semi auto basically operate as blowback designs, consider that. BTW, neither design loses velocity versus a fixed breech design.

Strange, MY 9mm is locked at firing same as my auto shotgun.

A gun writer once made a clamp to hold the bolt of a Ruger Mk 1 closed. He found slightly HIGHER velocity with the gun allowed to cycle than with the bolt held shut. His theory was that the initial slip as the bolt started to move let the case seal a bit better.

7.62 man · December 1, 2021, 10:33 AM

My Mossberg 500 has done it since I bought it using AA heavy loads. Not so much when I use light target loads. I just thought it was normal, it's not causing any problems so I'm not worried about it.

Prof Young · December 1, 2021, 10:40 AM

Thanks. This has been a real education.

Will shoot the gun with a lot more confidence in it now.

Prof Young

stuckinthe60s · December 1, 2021, 03:54 PM

its what makes the win 1200 and 1300 great. no time wasted getting the second shot in. perfectly normal.

**44 AMP** · December 1, 2021, 09:03 PM

And what makes the 1200 less than great is the poor design of the aluminum trigger group housing. There is a very thin part of the housing that anchors the spring that puts tension on the safety. If this breaks, the safety button can fall out.

I've seen this happen on two different 1200s that were otherwise undamaged.

A poor design, in my opinion.

bamaranger · December 2, 2021, 10:57 PM

Just for accuracy's sake, the bolt slightly retracts, clearing the ejection port.....the chamber is within the barrel and does not move.

November 29, 2021, 09:51 AM	#1
Prof Young Senior Member Join Date: August 21, 2007 Location: Illinois - down state Posts: 2,404	Chamber should stay closed . . . right? I have a Winchester 1300 12ga. It's a pump, of course. When I fire it, the chamber comes part way open. That should not happen, right? When you shoot a pump shotgun the chamber should stay closed until you pump it, right? It's been doing this for a while but it didn't click in my brain until yesterday that something is wrong. Help? Prof Young

November 29, 2021, 09:59 AM	#2
FITASC Senior Member Join Date: December 6, 2014 Posts: 6,446	Sounds like you are possibly pulling back on the pump fore end while firing? __________________ "I believe that people have a right to decide their own destinies; people own themselves. I also believe that, in a democracy, government exists because (and only so long as) individual citizens give it a 'temporary license to exist'—in exchange for a promise that it will behave itself. In a democracy, you own the government—it doesn't own you."- Frank Zappa

November 29, 2021, 10:12 AM	#3
Prof Young Senior Member Join Date: August 21, 2007 Location: Illinois - down state Posts: 2,404	Nope . . . Yeah I thought of that, but if I don't even have my support hand on the pump it still happens. Prof Young

November 29, 2021, 10:18 AM	#4
Virginian Senior Member Join Date: February 11, 2012 Location: Williamsburg, Va. Posts: 1,528	Perfectly normal. When you fire it it unlocks the pump mechanism. The swelling of the shell under pressure and recoil keeps the chamber closed until well after the ejecta is long gone out of the barrel. Most pumps do the same thing, but Winchester touted the fact theirs did it faster. If I shoot my Wingmaster one handed it will eject the empty shell. __________________ What could have happened... did.

November 29, 2021, 12:57 PM	#7
44 AMP Staff Join Date: March 11, 2006 Location: Upper US Posts: 28,833	Clean the gun make sure there is no crud built up where the bolt locks, then Fire the gun without your hand on the forearm (so there can be no question of you opening it) if the action opens, on its own, it needs work. __________________ All else being equal (and it almost never is) bigger bullets tend to work better.

November 29, 2021, 02:25 PM	#8
mehavey Senior Member Join Date: June 17, 2010 Location: Virginia Posts: 6,894	If the shooter has a normal forearm hold, that hold is in slight tension. When the action unlocks upon firing, that tension will naturally open the (now) unlocked action and pre-initiate the slide moving backward. It's one of the reasons that pump actions can be so incredibly fast.

November 29, 2021, 02:36 PM	#9
stagpanther Senior Member Join Date: March 2, 2014 Posts: 11,787	Interesting...my 870 never does that, even when I fire large magnums--does that mean something is *wrong* with it? __________________ "Everyone speaks gun."--Robert O'Neill *I am NOT an expert--I do not have any formal experience or certification in firearms use or testing; use any information I post at your own risk!*

November 29, 2021, 05:21 PM	#10
mehavey Senior Member Join Date: June 17, 2010 Location: Virginia Posts: 6,894	Took the tightest of the three 870's out tonite -- the ATAC. Ran light 3/4-oz skeet loads two loads with forearm hold -- it opened upon firing/unlock one with no forearm hold -- it was already unlocked/cracked open when I took hold of it again.

November 29, 2021, 05:27 PM	#11
Sharkbite Senior Member Join Date: November 4, 2013 Location: Western slope of Colorado Posts: 3,679	That is not unusual at all. Most pump guns unlock when you press the trigger. Then the recoil hits the bolt and trys to shove it to the rear. Sometimes that force is enough to move the fore-end/ bolt slightly open.

November 29, 2021, 09:08 PM	#13
44 AMP Staff Join Date: March 11, 2006 Location: Upper US Posts: 28,833	OK,so newer shotguns are supposed to work that way, I guess. I know for a fact that the Winchester Model 12 does not. ITs action remains firmly locked shut after the trigger is pulled, UNTIL you put some FORWARD pressure on the forearm. THEN it unlocks. Most of the time, the forward bump needed is supplied by a firm hold on the forearm, during recoil, Most model 12 shooters learn early on that you don't pull back on the forend when shooting you push forward until after the shot. The model 12 can be fired as fast as you can pump it, if its one of the originals without a trigger disconnector. Done that, too! the Rem 870 works a bit differently is slicker feeling, and of course has a disconnector. I don't have personal experience with the Win 1300 but if it was based on the Win 1200 its inferior to the Rem 870. In my opinion. __________________ All else being equal (and it almost never is) bigger bullets tend to work better.

November 29, 2021, 10:27 PM	#14
mehavey Senior Member Join Date: June 17, 2010 Location: Virginia Posts: 6,894	Notwithstanding my 870 post op cit, take a look at these three: https://thefiringline.com/forums/sho...7&postcount=11 https://thefiringline.com/forums/sho...3&postcount=12 https://thefiringline.com/forums/sho...9&postcount=13 Shucking forward does seem to unlock stuck brass.

November 30, 2021, 07:12 PM	#15
Jim Watson Senior Member Join Date: October 25, 2001 Location: Alabama Posts: 18,541	Gough Thomas once clamped weights to the foreend of an Ithaca 37 and shot it without holding the foreend. When he got the weights right, it kicked itself open and ejected the empty.

November 30, 2021, 10:00 PM	#18
The Happy kaboomer Senior Member Join Date: October 14, 2009 Posts: 226	It is normal. I shot a 1200 & 1300 for many years. It only unlocks AFTER the shot charge is gone. So no big deal. It will help you pump it faster........Don't worry.......Go shoot!

December 1, 2021, 07:03 AM	#19
Virginian Senior Member Join Date: February 11, 2012 Location: Williamsburg, Va. Posts: 1,528	The Winchester Model 12 was designed so that after the hammer drops the fore end must move forward slightly before it will come back. When a round is fired recoil takes care of that. In reading over this it would appear a lot of people do not understand the basic physics that govern operation. A.22LR or a 9mm semi auto basically operate as blowback designs, consider that. BTW, neither design loses velocity versus a fixed breech design. __________________ What could have happened... did.

December 1, 2021, 10:33 AM	#21
7.62 man Senior Member Join Date: April 30, 2009 Location: Cyber-world USA Posts: 258	My Mossberg 500 has done it since I bought it using AA heavy loads. Not so much when I use light target loads. I just thought it was normal, it's not causing any problems so I'm not worried about it.

December 1, 2021, 10:40 AM	#22
Prof Young Senior Member Join Date: August 21, 2007 Location: Illinois - down state Posts: 2,404	Thanks . . . Thanks. This has been a real education. Will shoot the gun with a lot more confidence in it now. Prof Young

December 1, 2021, 03:54 PM	#23
stuckinthe60s Senior Member Join Date: January 31, 2017 Location: Va., Ct., Mo.. Posts: 877	its what makes the win 1200 and 1300 great. no time wasted getting the second shot in. perfectly normal. __________________ Retired Military Aviation Former Member Navy Shooting Team Distinguished Pistol Shot,NRA Shotgun/Pistol Instructor NSSA All American, Skeet/Trap Range Owner

December 1, 2021, 09:03 PM	#24
44 AMP Staff Join Date: March 11, 2006 Location: Upper US Posts: 28,833	And what makes the 1200 less than great is the poor design of the aluminum trigger group housing. There is a very thin part of the housing that anchors the spring that puts tension on the safety. If this breaks, the safety button can fall out. I've seen this happen on two different 1200s that were otherwise undamaged. A poor design, in my opinion. __________________ All else being equal (and it almost never is) bigger bullets tend to work better.

December 2, 2021, 10:57 PM	#25
bamaranger Senior Member Join Date: October 9, 2009 Location: North Alabama Posts: 8,308	speech police Just for accuracy's sake, the bolt slightly retracts, clearing the ejection port.....the chamber is within the barrel and does not move.