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View Full Version : 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.