Blowback 22 long rifle conundrum

{Your answer doesn't explain why blowback isn't operated by the recoil of the cartridge firing and pushing back against the bolt

s I understand it. Blowback is operated by the recoil. And that the weight of the slide and recoil spring is heavy enough to hold the gun in battery until the pressure is lower or the bullet has exited the barrel. Then the recoil of the case blows the slide back.}

OK, It seems there's a problem with terminology. Cartridges DON'T RECOIL. The firearm recoils.
Generally speaking blowback actions have NO LOCKING features. The weight of slide/reciprocating parts, the resistance of a strong recoil spring, and friction are the only things holding the system closed during and after firing.
Recoil operated actions DO HAVE A LOCKED BREECH(again generally since there are so many variations) at the time of firing. Movement of the reciprocating parts initiates unlocking, extraction, and ejection.
 
"...the action type would not affect velocity..." Right. The action type has nothing to do with velocity.
"...as a semi auto gives up some velocity..." Nope. Blowbacks utilise the energy of *recoil*, not divert. The action is held closed by spring pressure only. No locking otherwise.
"The HK91 is like the G3 a recoil operated weapon incorporating a delayed
roller locked bolt system..." Isn't a blow back. More like a delayed blow back.
http://stevespages.com/pdf/hk_91.pdf
No 'gas' mentioned anywhere. http://stevespages.com/ipb-hecklerkoch-91a2.html
 
Once upon a time when I was a teenager I had a Stevens 87 (mine was an 87A). I really liked the optional locked breech mode, it made it possible to shoot CB Longs and the like. Sadly, I don't have it anymore.

Currently, I have a Marlin 60 which has a bolt that has the ability to be locked with the bolt held open in the same manner as the Stevens 87. It seems that it would only take a small modification to make a Marlin 60 have that locked breech mode -- just drill a coresponding recess like the 87 has.

Has anybody thought about doing such a mod? Or do people just accept that CB Longs won't completely stroke the action and leave it at that?
 
stubbicatt: Regarding the H&K G3, technically it is a roller delayed blowback.

And pure blowbacks really aren't held shut by the mainspring. The spring is there to return the bolt, feed the next round, etc. The inertial mass of the bolt/slide(if applicable) is what keeps the bolt in place. The bolt is moved backwards by gas pressure of the fired round pushing the case against the bolt face.

BTW -- one easy way to recognize a true recoil operated weapon is that the barrel is NOT fixed. The barrel and bolt travel backwards together under recoil until some mechanism retards or stops the barrel and allows the bolt to continue.
 
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A Browning A5 (as well as many Benellis and Stoegers) is recoil operated with a fixed barrel, but it is generally classified in the sub-class of "inertia operated" as opposed to recoil operated because it uses the entire gun as the recoil operated part of the system and the inertia of the bolt body (tendency to remain at rest) to cycle the action.
 
Mobuck said:
OK, It seems there's a problem with terminology. Cartridges DON'T RECOIL. The firearm recoils.
Click to expand...
I get it now. Your explanation helped. I've always understood each mechanism and the reasons for them, but I apparently was fuzzy on the specific physics behind it.
 
" for every action there is a equal and opposit reaction"
The gas that pushs the bullet down the barrel pushes the bolt/ slide/whatever back
 
When the idea of an auto-loading firearm first cropped up, various inventors first tried blowback. It worked OK as long as the cartridge was of low power, but when they tried to increase the power, the breech opened too soon and the cartridge burst, ruining the gun and often injuring the shooter. It soon became apparent that the mass of the breechblock just was not enough to keep a lid on high pressure until the bullet exited the barrel, so a lock of some kind would be needed.

Can a high pressure round be used in a blowback? Yes, but it was once calculated that for a .30-'06, the breech block would have to weigh 23 pounds, making the rifle just a bit heavy for normal use.

So various kinds of locked breech action have been derived, each with complications arising from weight, complexity and extra parts. Many designers have tried to attain the simplicity of the blowback without its disadvantages, but the results have been only partially successful. At the moment, most semi-auto rifles and pistols in low pressure calibers are blowback; most rifles in high pressure calibers have locked breeches, with some gas being bled off to operate the mechanism (M1, M16, AR, AK). Most pistols in powerful calibers are recoil operated, where the barrel and breech are locked together and recoil together until unlocked by some separate outside force (link or cam are the most common).

As you will gather from such a brief summary, there are many variations on the various themes, some feasible, others dead ends.

But let's be clear about one thing. The breech of a pistol like a 1911, M9, or Luger is locked. When those guns fire, the breech is locked just as surely and as solidly as the bolt of a Mauser rifle. It is the recoil of the barrel/slide unit that ultimately unlocks those parts from each other and allows the pistol to reload itself.

The rearward movement of the barrel/breech unit occurs because the bullet moves forward. If the bullet doesn't move, there is no recoil and the breech will not open, no matter the internal pressure. Blocking the barrel of a blowback pistol so the bullet can't move will result in damage to the gun; blocking the barrel of a 1911 so the bullet can't move results in - nothing.

NOTE that a recoil operated pistol is not functioned by gas pressure, except that the gas moves the bullet. As stated above, if the bullet is prevented from moving, nothing happens, even though the gas is pushing on the inside of the case in all directions.

Jim
 
Sorry, .45_Auto, but the A5 (and various copies and clones) does not have a fixed barrel. It operates by a system called "long recoil" in which the barrel and bolt are locked together until the unit reaches the rear of the receiver, at which point the barrel is unlocked to come forward under pressure from its spring (the one around the magazine tube). As the barrel reaches its full forward position, it unlocks the bolt to come forward, pick up an fresh shell and then re-lock into the barrel.

The Benelli is recoil operated in a wholly different (and clever) way. When the gun fires, it comes back, as a unit. A weight in the receiver tries to remain in place by inertia, compressing a short but powerful spring between the bolt carrier and itself. When the recoil force subsides, the spring reasserts itself, flinging the bolt carrier back to unlock the bolt. A separate, much lighter spring then returns the bolt to reloading the chamber and returning the bolt to battery.

Jim
 
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