Locked Breech Weapon?

[Guest TNDixieGirl]

I've looked it up, and I still don't understand the meaning. Can someone tell me, in very simple terms, what locked breech means?

[molonlabetn]

Locked breech is a term used to describe a weapon which contains the chamber pressure during firing by locking the bolt/slide to the barrel or barrel extension for a few milliseconds, until the bullet has left the barrel and the pressure in the chamber has subsided. This is accomplished in pistols by designing the barrel to move along a ramp which forces it upwards into the slide as it closes, and then move rearward and down away from the slide under recoil. Some pistols, and most autoloading rifles, use a rotating bolt or barrel to lock the parts together and delay the opening of the action so that wear and tear on the springs is minimized, and the force imparted upon the bolt/slide produces controllable movement.

Some guns are 'blowback' designs, and the only thing which holds the bolt/slide in battery is the tension of the spring... this is only feasible if the spring is very strong, the cartridge is very weak, or the mass of the bolt/slide is heavy.

Most pistols have locked breeches, if you notice that the barrel moves back and tilts up when you pull the slide back, this is a result of the design to use mechanical advantage to delay the ejection of the case, and reduce the force of the rearward motion of the action.

[dcloudy777]

I'll give it a shot. "Locked-breech" and "Blow-back" refer to the two main operating systems of autoloading firearms. Think for a minute about the way autoloaders work. The energy of the burning powder increases pressure in the barrel and pushes the bullet forward and the slide to the rear. This pressure is contained within the barrel until the barrel is vented to the outside by either the bullet leaving the barrel or the breech opens. The pressure being released from the muzzle end of the barrel results in the sound of a gunshot. If the breech opens (by pulling the spent case free from the chamber thus unsealing the breech), before the pressure in the barrel has subsided (i.e. before the bullet has left the muzzle), the high pressure gasses will travel back into the shooter, which is bad.

Now, herein lies a bit of a problem. The pressure exerted by the powder burning is the same in both direction, and except in the case of an extremely short barrel, the distance required to open the breech is quite a bit shorter than the distance the bullet must travel to release pressure the safer way. The practical autoloading firearm is derived from finding ways to slow the opening of the breech so that pressure is relieved safely through the muzzle.

It's actually easier to start with the opposite of locked-breech systems, known as blow-back operated guns. Gun that operate on the straight blow-back principal rely on weighting the reciprocating mass of the gun (slide or bolt) so that it's travel is slowed enough to delay opening of the breech until pressure has subsided. The biggest problem with blow-back guns is that they must be either relatively low-powered (nearly all rimfires use blow-back, as do most .25s, .32s, and .380s), or have really heavy bolts or slides (ever hefted a hi-point 45 or an Uzi?). This shortcoming quickly led to the invention of locked-breech systems.

Volumes have been written on various locked-breech operating systems, but basically they all operate by the breech being physically locked during the moment of ignition, where the energy engages some mechanism of mechanical advantage to unlock the breech before the reciprocating mass begins to open the breech. The most popular locked-breech system for handguns is the Browning-inspired tilting-barrel system. In said system, the barrel is physically locked into the slide by a lug or lugs when the gun is in battery. During recoil, the barrel moves back with the slide(still locked) until it is cammed upward, thus freeing the lugs and allowing the slide to continue back. The delay imparted by the moving and tilting barrel is sufficient to allow the bullet to leave the muzzle and reduce pressure inside the barrel to a safe level before the breech is open. Most autoloading rifles are gas operated, wherein the breech is locked until part of the gases from the burning powder are redirected to operate a mechanism that frees the bolt to travel rearward. This gas is drawn from a "down-barrel" point, and thus the distance the gas must travel before engaging the breech unlocking mechanism allows the pressure to reach safe levels before unlocking and opening the breech.

Beleive it or not, that's pretty over-simplified . Tons more locked-breech systems exsist, as well as hybrid delayed-blowback sytems, and a bunch more ways to skin a cat. Basically, a locked-breech gun is one in which the breech is physically locked at the moment of ignition, and must be unlocked by either manual force or the force generated by ignition before it can be opened.

DanO

[Guest db99wj]

Holy pocket protector moment batman.

[Guest flyfishtn]

Holy pocket protector moment batman.

[dcloudy777]

Yeah... sorry about that... but at least I do have the excuse of needing to know this kinda stuff for a living...

DanO

[Guest DrBoomBoom]

Here's an animation that shows the 1911, a locked breech weapon, in operation:

http://www.m1911.org/STI1911animation2.htm

[Guest db99wj]

Here's an animation that shows the 1911, a locked breech weapon, in operation:

http://www.m1911.org/STI1911animation2.htm

Neat, I have seen the one for Glocks. I was going to post a link but I searched and everything sent me to sniperworld.com but it looks as if their site doesn't work very well anymore, it is slow, to the point of not working at all.

[Guest canynracer]

I've looked it up, and I still don't understand the meaning. Can someone tell me, in very simple terms, what locked breech means?

I'll give it a shot. "Locked-breech" and "Blow-back" refer to the two main operating systems of autoloading firearms. Think for a minute about the way autoloaders work. The energy of the burning powder increases pressure in the barrel and pushes the bullet forward and the slide to the rear. This pressure is contained within the barrel until the barrel is vented to the outside by either the bullet leaving the barrel or the breech opens. The pressure being released from the muzzle end of the barrel results in the sound of a gunshot. If the breech opens (by pulling the spent case free from the chamber thus unsealing the breech), before the pressure in the barrel has subsided (i.e. before the bullet has left the muzzle), the high pressure gasses will travel back into the shooter, which is bad.

Now, herein lies a bit of a problem. The pressure exerted by the powder burning is the same in both direction, and except in the case of an extremely short barrel, the distance required to open the breech is quite a bit shorter than the distance the bullet must travel to release pressure the safer way. The practical autoloading firearm is derived from finding ways to slow the opening of the breech so that pressure is relieved safely through the muzzle.

It's actually easier to start with the opposite of locked-breech systems, known as blow-back operated guns. Gun that operate on the straight blow-back principal rely on weighting the reciprocating mass of the gun (slide or bolt) so that it's travel is slowed enough to delay opening of the breech until pressure has subsided. The biggest problem with blow-back guns is that they must be either relatively low-powered (nearly all rimfires use blow-back, as do most .25s, .32s, and .380s), or have really heavy bolts or slides (ever hefted a hi-point 45 or an Uzi?). This shortcoming quickly led to the invention of locked-breech systems.

Volumes have been written on various locked-breech operating systems, but basically they all operate by the breech being physically locked during the moment of ignition, where the energy engages some mechanism of mechanical advantage to unlock the breech before the reciprocating mass begins to open the breech. The most popular locked-breech system for handguns is the Browning-inspired tilting-barrel system. In said system, the barrel is physically locked into the slide by a lug or lugs when the gun is in battery. During recoil, the barrel moves back with the slide(still locked) until it is cammed upward, thus freeing the lugs and allowing the slide to continue back. The delay imparted by the moving and tilting barrel is sufficient to allow the bullet to leave the muzzle and reduce pressure inside the barrel to a safe level before the breech is open. Most autoloading rifles are gas operated, wherein the breech is locked until part of the gases from the burning powder are redirected to operate a mechanism that frees the bolt to travel rearward. This gas is drawn from a "down-barrel" point, and thus the distance the gas must travel before engaging the breech unlocking mechanism allows the pressure to reach safe levels before unlocking and opening the breech.

Beleive it or not, that's pretty over-simplified . Tons more locked-breech systems exsist, as well as hybrid delayed-blowback sytems, and a bunch more ways to skin a cat. Basically, a locked-breech gun is one in which the breech is physically locked at the moment of ignition, and must be unlocked by either manual force or the force generated by ignition before it can be opened.

DanO

:koolaid:

LOL...annnnndddd...Im lost

[Guest canynracer]

Holy pocket protector moment batman.

[Guest Boomhower]

LOL...annnnndddd...Im lost

...mall ninja

[Guest TNDixieGirl]

ok, I THINK I get it.

Maybe not totally, but at least I do have a better understanding of the term. My SW9VE is locked-breech right?

Thanks all.

[molonlabetn]

...My SW9VE is locked-breech right?

Yes. The barrel tilts to unlock the barrel and slide.