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 Stupid question... Can someone explain the difference between blowback vs recoil-operated
Casimir_Pulaski  [Team Member]
11/22/2011 7:00:36 PM EST
They sound like the same thing from reading wikipedia, I'll blame the pain pills I'm taking for getting 2 teeth pulled

I'm supposed to be writing a paper but got sidetracked

Thanks
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KC-10Boom  [Team Member]
11/22/2011 7:02:00 PM EST
Blowback is a type of recoil operation.

There are other types of recoil operation out there. I think Beretta uses a recoil operation for their shotguns.
the-fly  [Team Member]
11/22/2011 7:04:50 PM EST
Originally Posted By KC-10Boom:
Blowback is a type of recoil operation.

There are other types of recoil operation out there. I think Beretta uses a recoil operation for their shotguns.


My Xtrema2 is gas operated. I think its the Benelli's that are recoil operated, but i am not 100% sure.
fxntime  [Team Member]
11/22/2011 7:05:18 PM EST
Blowback, the weight of the slide and spring counteracts the "pushback" of the round as it fires. Nothing actually "locks" the barrel in place. Usually used in low power calibers or in a pistol with heavier slides and recoil springs.

Recoil operated [I assume locked breech] as recoil operated relates to both blowback and locked breach] is when the pistol slide is locked in place by the barrel and when it fires, the rearward motion is retarded by the locking method until pressures drop to a point where the slide unlocks from the barrel and moves rearward.

It is about the same with a long arm except for the majority of them, the bolt is locked to the barrel extension or the frame until pressure drops and it unlocks.
Casimir_Pulaski  [Team Member]
11/22/2011 7:05:29 PM EST

Originally Posted By KC-10Boom:
Blowback is a type of recoil operation.

There are other types of recoil operation out there. I think Beretta uses a recoil operation for their shotguns.

I mean like the difference between hi-points and most other firearms.

blowback vs locked breech, or whatever its called


FightingHellfish  [Team Member]
11/22/2011 7:11:34 PM EST
Originally Posted By fxntime:
Blowback, the weight of the slide and spring counteracts the "pushback" of the round as it fires.

Recoil operated [I assume locked breech] as recoil operated relates to both blowback and locked breach] is when the pistol slide is locked in place by the barrel and when it fires, the rearward motion is retarded by the locking method until pressures drop to a point where the slide unlocks from the barrel and moves rearward.

It is about the same with a long arm except for the majority of them, the bolt is locked to the barrel extension or the frame until pressure drops and it unlocks.


In weapons that I would consider to be "recoil operated" the barrel and bolt are locked together and both move to the rear until the movement of the barrel is stopped and some type of camming mechanism unlocks the bolt (or slide in the case of a pistol) which continues to the rear. You could consider both a .50 M2 and a 1911 to be recoil operated. The Johnson rifle and several classic shotguns also fit the bill.
Keith_J  [Team Member]
11/22/2011 7:12:19 PM EST

Originally Posted By Casimir_Pulaski:

Originally Posted By KC-10Boom:
Blowback is a type of recoil operation.

There are other types of recoil operation out there. I think Beretta uses a recoil operation for their shotguns.

I mean like the difference between hi-points and most other firearms.

blowback vs locked breech, or whatever its called



yes, recoil op has locked breech. Recoil also unlocks the action as momentum is conserved. The relatively light bullet is at high velocity but the mass divided by velocity is about the same for the slide.

Blowback have much larger masses so the action doesn't open by the max headspace distance before the bullet exits. Look at old .380s which were blowback but modern .380s which are 1/2 to 1/3rd the weight of the old ones are recoil operated.
Casimir_Pulaski  [Team Member]
11/22/2011 7:14:39 PM EST
So when the bullet leaves the barrel, the recoil unlocks the barrel so that the slide can move to the rear?

And in blowbacks just the force of the case moves the slide rearward, and the barrel doesn't unlock or move?

ETA: I think I figured it out. So my Ruger 22/45 is blowback, and my xdm is locked breech.

Messing around with them makes it easier to understand
FightingHellfish  [Team Member]
11/22/2011 7:17:25 PM EST
Originally Posted By Casimir_Pulaski:
So when the bullet leaves the barrel, the recoil unlocks the barrel so that the slide can move to the rear?

And in blowbacks just the force of the case moves the slide rearward, and the barrel doesn't unlock or move?




If you have a traditional centerfire autoloading pistol in the house, push the slide slowly to the rear, you'll notice that the barrel and slide initially move together, until the the barrel unlocks and then the slide continues by itself.
Ragin_Cajun  [Team Member]
11/22/2011 7:27:06 PM EST
Recoil operated systems use some sort of mechanical advantage to control rearward slide acceleration.

Blowbacks rely solely on spring pressure and the inertia of a large slide.
MillerSHO  [Team Member]
11/22/2011 7:28:00 PM EST
The modern .380 dropping the weight and going to a browning locked recoil system vs. a heavy blowback system is the reason for it's recent popularity.

The fewer blowback designs I've owned were just too heavy for what they brought to the table.

Keith_J  [Team Member]
11/22/2011 8:06:38 PM EST

Originally Posted By Casimir_Pulaski:
So when the bullet leaves the barrel, the recoil unlocks the barrel so that the slide can move to the rear?

And in blowbacks just the force of the case moves the slide rearward, and the barrel doesn't unlock or move?

ETA: I think I figured it out. So my Ruger 22/45 is blowback, and my xdm is locked breech.

Messing around with them makes it easier to understand

Yes, the slide and barrel are locked at firing and start moving back the instant the bullet starts moving. But because they move at a speed roughly the fraction of the slide/bullet mass compared to the bullet, they unlock after the bullet leaves the barrel. But load a VERY heavy bullet in a .45 ACP (like 500 grains) and it COULD unlock with the bullet still in the bore .

A blow-back's movement is quite the same, only the mass of the bolt is far greater and as such, the bolt doesn't move more than 0.003" before the bullet has left the barrel.

All hinges on physics, specifically the Law of Conservation of Linear Momentum. And yes, both designs have movement before the bullet leaves the barrel.
Casimir_Pulaski  [Team Member]
11/22/2011 8:09:02 PM EST

Originally Posted By Keith_J:

Originally Posted By Casimir_Pulaski:
So when the bullet leaves the barrel, the recoil unlocks the barrel so that the slide can move to the rear?

And in blowbacks just the force of the case moves the slide rearward, and the barrel doesn't unlock or move?

ETA: I think I figured it out. So my Ruger 22/45 is blowback, and my xdm is locked breech.

Messing around with them makes it easier to understand

Yes, the slide and barrel are locked at firing and start moving back the instant the bullet starts moving. But because they move at a speed roughly the fraction of the slide/bullet mass compared to the bullet, they unlock after the bullet leaves the barrel. But load a VERY heavy bullet in a .45 ACP (like 500 grains) and it COULD unlock with the bullet still in the bore .

A blow-back's movement is quite the same, only the mass of the bolt is far greater and as such, the bolt doesn't move more than 0.003" before the bullet has left the barrel.

All hinges on physics, specifically the Law of Conservation of Linear Momentum. And yes, both designs have movement before the bullet leaves the barrel.
Thanks

Andr0id  [Team Member]
11/22/2011 8:25:51 PM EST
OK, now time for gas-delayed blowback.



AL_Safety  [Member]
11/22/2011 8:33:55 PM EST
Originally Posted By Keith_J:

Originally Posted By Casimir_Pulaski:
So when the bullet leaves the barrel, the recoil unlocks the barrel so that the slide can move to the rear?

And in blowbacks just the force of the case moves the slide rearward, and the barrel doesn't unlock or move?

ETA: I think I figured it out. So my Ruger 22/45 is blowback, and my xdm is locked breech.

Messing around with them makes it easier to understand

Yes, the slide and barrel are locked at firing and start moving back the instant the bullet starts moving. But because they move at a speed roughly the fraction of the slide/bullet mass compared to the bullet, they unlock after the bullet leaves the barrel. But load a VERY heavy bullet in a .45 ACP (like 500 grains) and it COULD unlock with the bullet still in the bore .

A blow-back's movement is quite the same, only the mass of the bolt is far greater and as such, the bolt doesn't move more than 0.003" before the bullet has left the barrel.

All hinges on physics, specifically the Law of Conservation of Linear Momentum. And yes, both designs have movement before the bullet leaves the barrel.


Load that same heavy like 500 grain bullet in a blowback, and it will likely result in a case explosion as well. Blowback guns are designed on a bullet weight / pressure curve just like locked breech guns. Results will vary based on actual gun design. While I don't have access to the design data, I'd be surprised if a blowback operated .45 would function with 500 grain bullets.
Auto5guy  [Team Member]
11/22/2011 8:47:35 PM EST

Originally Posted By Casimir_Pulaski:

Originally Posted By Keith_J:

Originally Posted By Casimir_Pulaski:
So when the bullet leaves the barrel, the recoil unlocks the barrel so that the slide can move to the rear?

And in blowbacks just the force of the case moves the slide rearward, and the barrel doesn't unlock or move?

ETA: I think I figured it out. So my Ruger 22/45 is blowback, and my xdm is locked breech.

Messing around with them makes it easier to understand

Yes, the slide and barrel are locked at firing and start moving back the instant the bullet starts moving. But because they move at a speed roughly the fraction of the slide/bullet mass compared to the bullet, they unlock after the bullet leaves the barrel. But load a VERY heavy bullet in a .45 ACP (like 500 grains) and it COULD unlock with the bullet still in the bore .

A blow-back's movement is quite the same, only the mass of the bolt is far greater and as such, the bolt doesn't move more than 0.003" before the bullet has left the barrel.

All hinges on physics, specifically the Law of Conservation of Linear Momentum. And yes, both designs have movement before the bullet leaves the barrel.
Thanks


In pistols, the Browning style recoil action is more complex to design and manufacture but it's huge advantage is in weight savings. The weight of the barrel is added to the mass of the slide to resist the force of the bullet. In a blow-back the mass of the slide alone must be great enough to resist the force. The barrel plays no part but its weight is added to the overall package.

Blow-back designs are cheap to make so they are associated with low quality but because the barrel never moves, the design can be capable of fine accuracy if made correctly.

When shooting a Browning style lock up, hot loads do sometimes prematurely unlock the action. You verify this by looking at the spent brass. The primer should have a perfectly round dent from the firing pin. If the primer dent looks like a line or a crease, the load is too hot. What is happening is that the barrel is trying to tilt down while there is still pressure and recoil forcing the brass and firing pin together. This is referred to as the firing pin wiping the primer and it means you need to use a lighter load or get a stiffer recoil spring.

JBlitzen  [Team Member]
11/22/2011 8:49:46 PM EST
OP, non-blowback recoil operation will usually mean the barrel moves part of the way with the breech.

This is pretty obvious if you watch the barrel carefully as you rack the slide.

On blowback pistols like .22's and .380's and cheap-ass bulky high points, the barrel won't move at all when the slide moves. It's simply fixed in place.

Gas operated pistols also have barrels that don't move (like, of course, AR-15's). But they're using a different mechanism for delaying the chamber unlocking. Blowback weapons don't use any such mechanism beyond inertia.

My Benelli M2 shotgun, incidentally, is not recoil or blowback operated. It's inertia operated, which is totally different. In that case, there's essentially a freefloating heavy mass behind the bolt, connected only by a spring and resting on rails. When the weapon is fired, recoil shoves the weapon backward. The heavy mass doesn't move much due to inertia, but the bolt does, compressing the spring as a result. After a bit of movement, the weapon stops its rearward motion. At this point, the compressed spring starts to expand, pushing the heavy mass back away from the bolt. The mass moves rearward independently of the rest of the weapon, and it eventually reaches a point where it pulls the spring, connected to the bolt. The expanded spring pulls the bolt free of the chamber, and there you go. The weapon cycles.

It's a weird system.

Anyway, wikipedia has good entries on blowback, recoil operation, and inertia operation. I suggest you read through them and look at the pictures.
9mmRandy  [Team Member]
11/22/2011 8:55:19 PM EST
Why are blow back guns so dirty? Lot's of powder residue in my Marlin Camp 9.
straatconst  [Team Member]
11/22/2011 9:47:37 PM EST

Originally Posted By Andr0id:
OK, now time for gas-delayed blowback.

http://upload.wikimedia.org/wikipedia/commons/thumb/6/60/HK-P7.jpg/300px-HK-P7.jpg



After that, the long recoil system.



bloodsport2885  [Team Member]
11/22/2011 10:17:46 PM EST
Originally Posted By Casimir_Pulaski:
So when the bullet leaves the barrel, the recoil unlocks the barrel so that the slide can move to the rear?

And in blowbacks just the force of the case moves the slide rearward, and the barrel doesn't unlock or move?

ETA: I think I figured it out. So my Ruger 22/45 is blowback, and my xdm is locked breech.

Messing around with them makes it easier to understand


Pull back the slide of your XD slowly. You'll notice the barrel tips down slightly. This the the barrel (that squarish portion of the barrel is the ocking lug) unlocking from the slide. Blowback does not have this. The barrel is fixed in position and the weight of the slide provides resistance to the extraction and ejection of the round until pressures are safe within the case and barrel.
30calTBLkid  [Team Member]
11/22/2011 11:27:39 PM EST
Originally Posted By straatconst:

Originally Posted By Andr0id:
OK, now time for gas-delayed blowback.

http://upload.wikimedia.org/wikipedia/commons/thumb/6/60/HK-P7.jpg/300px-HK-P7.jpg



After that, the long recoil system.


http://i43.photobucket.com/albums/e354/olds-mo-boo-ble/FROMMERSTOP.jpg


Then, gas tappet. So solly no pic.

ETA:found one.
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