# Blow back vs locked breech?



## teslaman (Feb 13, 2014)

Hi Everyone,

I have owned many revolvers but have just purchased my first semiautomatic (a Ruger LC 380). I am having trouble understanding why the locked breech design absorbs more energy and gives less kick back. I have studied all the sites showing the different mechanics of the two systems, but I cannot see why one gives less kick than the other. Is some of the energy absorbed by the small barrel movement in the locked breech configuration??

Thanks, gun experts!!


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## Bhoffman (Nov 10, 2013)

Gust a guess, but...

With a blowback system, the gun's slide starts to move rearward immediately after ignition.

A locked breach delays that process by requiring the breach to unlock before the slide can move. This allows the bullet to travel further down the barrel (and possibly exit the barrel) thus expending more energy.


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## Steve M1911A1 (Feb 6, 2008)

...Also, the act of unlocking and moving the barrel, before the slide moves significantly toward the rear, absorbs some amount of recoil impulse. It also changes the impulse's direction slightly, pushing the pistol deeper into the shooter's hand rather than merely flipping its muzzle upwards.

One can comfortably shoot a tiny .380 ACP pocket gun because of its locked breech. Were such a pistol of the straight-blowback persuasion, shooting it would be a literal pain.


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## rex (Jan 27, 2012)

That pretty much sums it up. The recoil spring is also a factor. 

In a blowback system there must be mass to slow the slide to get the bullet out of the barrel before the case leaves the chamber, this is accomplished with varying degrees of weight in the slide and a stiff recoil spring. With that restraint the energy is transferred into the frame, which causes the increased muzzle flip.

With the locked breach, the first roughly 1/4" of rearward movement has the slide and barrel locked together before the barrel unlocks and drops down for the slide to continue rearward. Now you have the added weight of the barrel on top of the slide and the spring's resistance. On a hammer fired gun, cocking the hammer also provides resistance so the recoil spring can be less than a blowback design. Now the recoil spring basically has to do it's intended job, returning the slide forward and not being relied on to slow rearward slide travel. The spring does have a small part in dampening rearward movement, but nothing like a blowback design. Striker fired locked breach guns (at least the few I've tried) are kind of between the 2, the striker spring can only be so heavy or the trigger pull sucks so the recoil spring seems to be heavier than a hammer gun. That's just my take on them because the spring seemed heavier to me than a hammer gun. but I've never investigated the actual weigh differences between the 2.


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