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Discussion Starter · #1 · (Edited)
Is there a way to tell, by photo, if a gun is locked breech or blowback etc?

At the risk of over simplifying and sounding stupid, can it be as simple as identifying if it has a floating barrel or fixed?

I mean, if you can see a picture of the slide racked and locked back and notice that the barrel tip is angled upward, would that not indicate locked breech.

And visa versa if barrel parallel to frame indicating fixed, thus blowback?
 

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One way is to look how the barrel is in relation to the slide when close.
Most blow backs do not allow the rear portion of the barrel to mesh or engage the slide.

The "pocket" pistols could be an example. The Kel-Tec P3AT has a barrel that the rear is flush with the top of the slide. As the slide retracts, the rear of the barrel cams down.

The PPK (blow back) barrel does not cam down.

When the slide is retracted, any movement of the barrel indicates that the firearm is not a blow back.
 

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There are always exceptions. The beretta 92 and its kin are direct blowback, the only 9mm handgun i know of that is such, but the barrel disengaging the slide is delayed. Its what makes their cyclic rate so blindingly fast.
 

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The M9 is a bit of a weird duck, but is actually recoil/ blowback, with a locked breech. From the FM on the M9-

"Blowback reaction generated by the exploding charge thrusts the locked barrel/slide system rearward against the recoil spring. After recoiling about 3 mm (1/8"), the barrel and slide unlock, allowing the barrel to tilt down into the locked position. The slide continues rearward until it abuts against the receiver stop."
 

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The M9 is a bit of a weird duck, but is actually recoil/ blowback, with a locked breech. From the FM on the M9-

"Blowback reaction generated by the exploding charge thrusts the locked barrel/slide system rearward against the recoil spring. After recoiling about 3 mm (1/8"), the barrel and slide unlock, allowing the barrel to tilt down into the locked position. The slide continues rearward until it abuts against the receiver stop."
Isn't that just how most locked breech handguns fire? :confused:
 

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There are always exceptions. The beretta 92 and its kin are direct blowback, the only 9mm handgun i know of that is such, but the barrel disengaging the slide is delayed. Its what makes their cyclic rate so blindingly fast.
The H&K PSP P7, and variants, are fixed barreled, blow back, 9mms.
The delay in slide retraction is done by the gases bled off the cartridge.

The Hi-Point 9mm and .45ACP are of the blow back design.
 

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Discussion Starter · #7 ·
One way is to look how the barrel is in relation to the slide when close.
Most blow backs do not allow the rear portion of the barrel to mesh or engage the slide.
Okay, that's an interesting and logical sounding way to think about/look at it.

Let me see if I understand correctly. If, when looking at a semiautomatic pistol on the right side with shell ejection port, the top of the barrel, which is visible through the porthole, isn't flush with the slide, it's quite possibly, if not most likely, blowback?

So like my Firestars, where the barrels are completely shrouded by the slide, are probably blowback operated?

Picture of guns found here for reference...
http://world.guns.ru/handguns/hg/sp/star-firestar-e.html

Thanks Dan!
 

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Discussion Starter · #8 ·
There are always exceptions. The beretta 92 and its kin are direct blowback, the only 9mm handgun i know of that is such, but the barrel disengaging the slide is delayed. Its what makes their cyclic rate so blindingly fast.
Very interesting. It's the any simple way to explain how they achieve our even why they would incorporate such a system?

Do you have a preference in these actions by the way? And if so, would you mind briefly telling me why.

I've been under the assumption that locked breech was the most reliable, but that was an uneducated guess and I wish to get educated.
 

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Okay, that's an interesting and logical sounding way to think about/look at it.

Let me see if I understand correctly. If, when looking at a semiautomatic pistol on the right side with shell ejection port, the top of the barrel, which is visible through the porthole, isn't flush with the slide, it's quite possibly, if not most likely, blowback?

So like my Firestars, where the barrels are completely shrouded by the slide, are probably blowback operated?

Picture of guns found here for reference...
http://world.guns.ru/handguns/hg/sp/star-firestar-e.html

Thanks Dan!
I read the tech info and it says that those firearms in your reference are cam operated. The barrel looks to be like a blow back, but in reality, they have 1 or more lugs or some part of the barrel that engages the slide.
 

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Discussion Starter · #10 ·
I read the tech info and it says that those firearms in your reference are cam operated. The barrel looks to be like a blow back, but in reality, they have 1 or more lugs or some part of the barrel that engages the slide.
Yeah, that's why I asked. It says it uses some Browning cam locking system or something like that right?

So am I safe to assume this "cam locking" is the same as a breech lock action?

Maybe there simply is no way to tell by pictures. Lol

Thanks again for the consultation Dan!
 

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The blow back or cam system have ways to allow the chamber to open after pressure is released by the bullet. The pressure rapidly decreases after the bullet exits the barrel.

Which is more reliable? Both have been around for years and probably will be around for more years.
The Hi-Point handguns use the physics of more energy needed to move mass. The PPK uses springs (recoil and main). The 1911 (and others) use a link to keep slide and barrel together until pressures decreases. Others use a camming system.

Comparing two different .380s (one a PPK/s, the other is a Kel-Tec P3AT), I have found that, for me, the PPK/s is more accurate.
Comparing my H&K PSP P7 (blowback) to a clone of the Browning Hi-Power, they both are reliable. And depending on ammo, the accuracy is not much different (I did some work on the BHP clone before this).

I would not worry about which is more reliable in making your decision. If the firearm was not reliable, it would not stay on market too long (except the dern Jimenez/Jennings pistol).
 

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Discussion Starter · #12 ·
The blow back or cam system have ways to allow the chamber to open after pressure is released by the bullet. The pressure rapidly decreases after the bullet exits the barrel.

Which is more reliable? Both have been around for years and probably will be around for more years.
The Hi-Point handguns use the physics of more energy needed to move mass. The PPK uses springs (recoil and main). The 1911 (and others) use a lint to keep slide and barrel together until pressures decreases. Others use a camming system.

Comparing two different .380s (one a PPK/s, the other is a Kel-Tec P3AT), I have found that, for me, the PPK/s is more accurate.
Comparing my H&K PSP P7 (blowback) to a clone of the Browning Hi-Power, they both are reliable. And depending on ammo, the accuracy is not much different (I did some work on the BHP clone before this).

I would not worry about which is more reliable in making your decision. If the firearm was not reliable, it would not stay on market too long (except the dern Jimenez/Jennings pistol).
I guess so. Still I like to educate myself on the mechanics of things. I've taken them apart and put back together but even then it's not like I'm re or reverse engineering something, so it's nice to get an understanding of how and why things I'm interested in work the way they do...

I did reference the user manual on these and it said this:

Ribs on top of barrel engaging recesses in ceiling of slide when breech block face of slide strikes barrel on its forward movement and pushes it ahead and up on its oval shaped pivoting hole in barrel lug.

Going to decipher what that all means later! Lol haven't even eaten breakfast yet and this is already too much to digest! Lol

Thanks again man!
 

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danf_fl said:
The H&K PSP P7, and variants, are fixed barreled, blow back, 9mms.
The delay in slide retraction is done by the gases bled off the cartridge.

The Hi-Point 9mm and .45ACP are of the blow back design.
the P7 almost like a short stroke piston, right?
Man I love that pistol.
 
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