What "locks" the action on a pump gun?

kotengu · September 18, 2002, 08:34 AM

I just finished blasting, parkerizing, and painting my "project" gun (a cheap Chinese knock-off of an Ithaca 37), and I understand the functioning much better now. What I can't quite figure out, though, is what keeps the action "locked" while firing, then somehow unlocks so you can pump it.

In other words - on my friends Winchester 1300 you can keep rearward pressure on the forend with your weakhand, and when you pull the trigger the pump immediately cycles backward. It makes for very fast cycling and you almost forget you're doing it after a few times. On mine (and most others from what I understand), if you put rearward pressure on the pump and pull the trigger, you have to release the pressure, THEN pump it or it won't go. Do I have this right, or is this a fault of mine being a cheap-o Chinese model?

I guess another way of saying it is "what allows the slide to come back after firing?" instead of having to thumb the slide release?

Thanks in advance,
Matt

redneck · September 18, 2002, 11:59 AM

It varies from gun to gun. Sounds like the locking mechanism on yours is supposed to sort of bind in the action, can't move while its under pressure.

**Mike Irwin** · September 18, 2002, 03:22 PM

The Winchester uses a rotary bolt head that starts to disengage almost immediately when the action uncocks. I've got a pump-action 1200 that has always been very fast.

Other guns, however, require a slight forward motion for the action to fully unlock.

When you're actually shooting the recoil of the gun does this step for you.

BigG · September 18, 2002, 10:15 PM

I would say it's the cheap knock off. Usually a 37 unlocks on the trigger pull jes like the other pumps.

HSMITH · September 19, 2002, 10:32 PM

You have a tilting bolt shotgun. The rearward movement when fired locks the bolt tighter up into the barrel extension or reciever depending on type. When you pull back on the slide you are in effect tightening the lockup. The rotary bolt of the 1300 is responsible for it unlocking after firing.

SDC · September 20, 2002, 09:35 AM

This is also a "safety feature" of sorts, intended to stop you from firing the shotgun when it isn't completely locked up; can you imagine what would happen if you were able to fire the shotgun if the bolt wasn't completely locked to the barrel and/or receiver? I once had a POS Eastfield that broke a firing pin, and when I pumped forward one time, the loose forward part of the firing pin wedged in the front position and fired a shell while I was still closing the action; the recoil tore the pump out of my hand, and the hull looked pregnant, but if that shell had gone off just a little bit sooner, all the pressure would have come out the ejection port. In most pump-action guns, there's a little moving lever that wedges the bolt into the locked posiiton when you close the action with a cocked hammer, and you release that lever either by 1) firing a shot or 2) using the action-release, so you can clear the chamber.

September 18, 2002, 08:34 AM	#1
kotengu Member Join Date: November 21, 2001 Location: Cookeville, TN Posts: 71	What "locks" the action on a pump gun? I just finished blasting, parkerizing, and painting my "project" gun (a cheap Chinese knock-off of an Ithaca 37), and I understand the functioning much better now. What I can't quite figure out, though, is what keeps the action "locked" while firing, then somehow unlocks so you can pump it. In other words - on my friends Winchester 1300 you can keep rearward pressure on the forend with your weakhand, and when you pull the trigger the pump immediately cycles backward. It makes for very fast cycling and you almost forget you're doing it after a few times. On mine (and most others from what I understand), if you put rearward pressure on the pump and pull the trigger, you have to release the pressure, THEN pump it or it won't go. Do I have this right, or is this a fault of mine being a cheap-o Chinese model? I guess another way of saying it is "what allows the slide to come back after firing?" instead of having to thumb the slide release? Thanks in advance, Matt __________________ "The way is in training" - Miyamoto Musashi

September 18, 2002, 11:59 AM	#2
redneck Senior Member Join Date: December 20, 2001 Location: Ohio Posts: 364	mechanics of every gun are different It varies from gun to gun. Sounds like the locking mechanism on yours is supposed to sort of bind in the action, can't move while its under pressure. __________________ Fix it right the first time... Use Baling Wire !

September 18, 2002, 03:22 PM	#3
Mike Irwin Staff Join Date: April 13, 2000 Location: Northern Virginia Posts: 41,379	The Winchester uses a rotary bolt head that starts to disengage almost immediately when the action uncocks. I've got a pump-action 1200 that has always been very fast. Other guns, however, require a slight forward motion for the action to fully unlock. When you're actually shooting the recoil of the gun does this step for you. __________________ "The gift which I am sending you is called a dog, and is in fact the most precious and valuable possession of mankind" -Theodorus Gaza Baby Jesus cries when the fat redneck doesn't have military-grade firepower.

September 18, 2002, 10:15 PM	#4
BigG Senior Member Join Date: May 19, 1999 Location: Atlanta, GA Posts: 4,334	I would say it's the cheap knock off. Usually a 37 unlocks on the trigger pull jes like the other pumps. __________________ o "The Earth is degenerating today. Bribery and corruption abound. Children no longer obey their parents, every man wants to write a book, and it is evident that the end of the world is fast approaching." Assyrian tablet, c. 2800 BC o "In the beginning of a change, the patriot is a scarce man brave, hated, and scorned. When his cause succeeds, however, the timid join him, for then it costs nothing to be a patriot." Mark Twain o "They have gun control in Cuba. They have universal health care in Cuba. So why do they want to come here?" Paul Harvey o TODAY WE CARVE OUT OUR OWN OMENS! Leonidas, Thermopylae, 480 BC

September 20, 2002, 09:35 AM	#6
SDC Senior Member Join Date: January 23, 2001 Location: People's Republic of Kanada Posts: 1,652	This is also a "safety feature" of sorts, intended to stop you from firing the shotgun when it isn't completely locked up; can you imagine what would happen if you were able to fire the shotgun if the bolt wasn't completely locked to the barrel and/or receiver? I once had a POS Eastfield that broke a firing pin, and when I pumped forward one time, the loose forward part of the firing pin wedged in the front position and fired a shell while I was still closing the action; the recoil tore the pump out of my hand, and the hull looked pregnant, but if that shell had gone off just a little bit sooner, all the pressure would have come out the ejection port. In most pump-action guns, there's a little moving lever that wedges the bolt into the locked posiiton when you close the action with a cocked hammer, and you release that lever either by 1) firing a shot or 2) using the action-release, so you can clear the chamber. __________________ Gun control in Canada: making the streets safer for rapists, muggers, and other violent criminals since 1936.

September 19, 2002, 10:32 PM	#5
HSMITH Senior Member Join Date: June 21, 2002 Posts: 2,019	You have a tilting bolt shotgun. The rearward movement when fired locks the bolt tighter up into the barrel extension or reciever depending on type. When you pull back on the slide you are in effect tightening the lockup. The rotary bolt of the 1300 is responsible for it unlocking after firing.

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