lack of recoil-operated semi rifles?... why?

[Gtscotty]

And the Barrett is an apples to oranges comparison when you are talking about a 30 pound, purpose built rifle that IS capable of great accuracy, but gives up the mobility of a service rifle or carbine.

It also gives up economy.... at $8-9K a copy, they certainly aren't giving them away. That price level allows for the custom fitting necessary for a recoil operated rifle to achieve the Barrett's excellent level of accuracy. I really don't think you'd be able to build a recoil operated AR-15/AR-10-like rifle with equivalent accuracy for the same price... Having the barrel AND action jump back and forth with each shot is just really not as conducive to accuracy as having the barrel remain in one spot, and the bolt move linearly. I'm not saying it can't be done, its just not the cheapest/most efficient way to go about building an accurate yet reasonably light weight self loading rifle.

Blowback and delayed blowback are variants of gas operated: the case is a one use, throw away gas piston.

.... Correct, in a somewhat esoteric sense, but not really useful. When someone refers to a gas operated action, I think we can safely assume they are generally not referring to a blowback action.

 

[PercyShelley]

Interesting that other posters' experience with the Remington 81 does not mirror my own. I wonder if there is a friction buffer that gets worn out over time. I seem to recall that the auto 5, which is a related design, has something like that.

I have heard, but have not personally verified, that Johnson 1941s are prone to vertical stringing. Whether that's a function of the moving barrel, I would not venture to speculate.

While fussing with a 1911 I noticed something that might limit the scaling on Browning-style tilting barrel short-recoil designs. Because the barrel is tilted out of engagement with the slide while unlocked there is a slight angle between the bore axis and the bolt axis during feeding. This is not a huge issue with stubby pistol rounds (although some have fingered this angle as a potential source of feeding problems in sub-compacts because the angle is larger due to the shorter barrel), but with the long, skinny rifle rounds it seems possible that the round could catch during feeding, or slip from under the extractor.

Most recoil-operated rifles use a separate bolt and bolt carrier, but this would suggest that the most common recoil operated design does not scale up well.

 

[jason41987]

hmm.. ive been thinking about it.. and i wonder... what if there was a recoil operated rifle in which the barrel didnt actually move.. more so like a rear-piston gas system..

imagine this.. the inside of the breach of the barrel is hollowed out.. inside this fits a chamber block that holes and supports the cartridge... when you fire it, this block holding the cartridge slams back, hits a block, forcing the bolt to continue without it, extracting the cartridge... since the breach plug wouldnt completely exit the rear of the barrel, no gasses would escape into the action, they would all be sent forward while the barrel remains still giving the rifle a recoil operation, or an enclosed blowback action, or the breach block could act as a short-stroke piston....

thats one idea ive been working on designing in 3D

 

[jason41987]

hmm.. i can see a problem with fouling in that last idea... might give you the same problems an HK rifle has with buildup in the roller recesses in the barrel

 

[Sam1911]

Have you looked into how the Benelli inertia system works? http://www.benelliusa.com/innovations/

 

[PercyShelley]

jason41987, look up the "floating chamber" .22 adaptors for the 1911. They work similarly to what you describe.

 

[68wj]

jason41987, look up the "floating chamber" .22 adaptors for the 1911. They work similarly to what you describe.

To increase felt recoil.

I still don't get the fear of a gas system. Oh noes, gas gets in the action and it is dirty. It is debatable there is any affect on function, and proven that even when stoppages are blamed on fouling, it takes a massive amount of fired rounds to do anything other than make a mess.

Considering cost, accuracy, weight, and reliability, there is currently no better system than gas operated for high power firearms. An autoloader requires an energy source to function, but where does the energy come from? The simple rearward energy (recoil) of a .308 gives ~19-22 ft/lbs while some of that is also absorbed by the shooter and affected by the weight of the firearm. All the while, the action must contain ~60,000 PSI of pressure inside of the chamber. A gas system taps some of that high pressure and uses the energy to cycle the action independent of the shooter's shoulder or weapon's weight. There is the variable of gas pressure for various loads, but a much larger operating window. A 9mm pistol is approximately half the pressure, and a 12ga shotgun even less, so alternate operating systems are more suited here and sometimes ideal.

 

[PercyShelley]

To increase felt recoil.

I still don't get the fear of a gas system. Oh noes, gas gets in the action and it is dirty. It is debatable there is any affect on function, and proven that even when stoppages are blamed on fouling, it takes a massive amount of fired rounds to do anything other than make a mess.

Considering cost, accuracy, weight, and reliability, there is currently no better system than gas operated for high power firearms. An autoloader requires an energy source to function, but where does the energy come from? The simple rearward energy (recoil) of a .308 gives ~19-22 ft/lbs while some of that is also absorbed by the shooter and affected by the weight of the firearm. All the while, the action must contain ~60,000 PSI of pressure inside of the chamber. A gas system taps some of that high pressure and uses the energy to cycle the action independent of the shooter's shoulder or weapon's weight. There is the variable of gas pressure for various loads, but a much larger operating window. A 9mm pistol is approximately half the pressure, and a 12ga shotgun even less, so alternate operating systems are more suited here and sometimes ideal.

More to the point, it increases the recoil velocity of the moving parts, an important consideration if you want to shove around a slide originally dimensioned for a .45 with a mere .22.

I recall a test on arfcom or somesuch were a barrel was chronographed before and after the gas port was drilled. The difference in velocity was slightly above the level of statistical noise (~30 FPS). Most gas systems on semi-auto rifles are designed to bleed gas off after a certain distance. The problem is not finding sufficient energy to cycle the action (excepting weird corner cases like .22 conversions). The problem is managing the enormous amount of energy that there is.

That said, I don't see anything dreadfully wrong with the idea of a recoil-operated rifle. Certainly, it would take a hit in accuracy, but for many applications this wouldn't be enough to matter. A recoil-operated rifle that were only as accurate as, say, an HK USP or custom-tuned 1911 would be more than accurate enough for whacking tasty ungulates at typical distances.

You would shed the mass of the gas system, but you would have to reinforce the receiver where the barrel would be bonking into it. The action is locked, same as a gas-op weapon, so it could handle quite powerful cartridges (as the M82 proves). There would be some sensitivity to using different barrel lengths due to the extra weight, but retarded blowbacks and gas-op rifles usually have to compensate for the longer pressure curve in different length barrels by roller geometry or gas port diameter. So really, it doesn't make an enormous difference which of the three major* self-loading operations cycles a design uses.

The one big advantage I see is that since the barrel is already floating in the receiver, it's fairly easy to remove on most recoil-operated designs. A recoil operated rifle would lend itself well to being a takedown design, and indeed the Remington 81 I've shot could be broken down into two reasonably small halves.


*Now, blow-forward actions, those are just silly.

 

[earplug]

Accuracy

A recoil operated firearm may be very accurate when new. But the barrel sliding and recoiling parts would wear over time. Consider the wear on a match grade pistol.
A fixed barrel design does not have this problem.

 

[jason41987]

seems a floating chamber would give you most most the benefits of a recoil operated design without the negatives which all seem to be present because the barrel itself moves...

this post doesnt neccessarily mean im looking for anything recoil operated, or that it may or may not be a better design... but as this conversation moves on it seems it has roughly the same number of benefits and tradeoffs as any of the other action types (blow back or gas)... which actually doesnt answer any questions... just makes me wonder even more why they, for the most part, just dont exist in rifles... as a student of engineering (i say this not to say im still in school for it, but to emphasize that you'll never stop learning) its in my nature to ask "why" especially when the answers seem to be so elusive

 

[briansmithwins]

seems a floating chamber would give you most most the benefits of a recoil operated design

Floating chambers amplify blowback operation. Useful when doing .22LR conversions but overkill otherwise.

Look up 'primer actuation' for kicks.

If you're a engineering student interested in firearms you need to read The Machine Gun by Col. Chinn. More ideas have been discovered pertaining to firearms than stars in the sky.

http://www.germanmanuals.com/Links.html

BSW

 

[moxie]

Gtscotty is correct. Blowback does not equal recoil operated. the M3 and others mentioned are blowbacks, mostly operating from an open bolt.

 

[Slamfire]

That said, I don't see anything dreadfully wrong with the idea of a recoil-operated rifle. Certainly, it would take a hit in accuracy, but for many applications this wouldn't be enough to matter. A recoil-operated rifle that were only as accurate as, say, an HK USP or custom-tuned 1911 would be more than accurate enough for whacking tasty ungulates at typical distances

.


The basic problem is that it has been so long since these issues where actually hashed out as hardware, no one who was alive then when the downselect occurred, is around now. It is beyond living memory.


LTC Chin's book of the Machine Gun Vol IV goes over the advantages and disadvantages of different mechanisms.


Whatever the theorical advantages of one type over another, what we do know is that gas operation is the most common mechanism for high powered semiautomatic rifles.

And, I don't know exactly why, but it must be because it worked better.

 

[conhntr]

//It also gives up economy.... at $8-9K a copy, they certainly aren't giving them away. That price level allows for the custom fitting necessary for a recoil operated rifle to achieve the Barrett's excellent level of accuracy. I really don't think you'd be able to build a recoil operated AR-15/AR-10-like rifle with equivalent accuracy for the same price//

There is a 1911 manufacturer that can gurantee 50 yard accuracy of 1.5" for 1500$.

 

[briansmithwins]

The big advantage of gas operation is you've got a lot of power to work with and can change the variables a lot. Gas port location, size, and gas piston diameter can all be changed to get the desired result. It's also a lot easier to protect the reciprocating parts (gas piston, operating rod) with some type of shroud than it is to enclose a reciprocating barrel.

BSW

 

[mortablunt]

o besides the johnson rifle which, to my understanding wasnt produced much due to reliability issues with a bayonet attached, and higher cost of production, slower reloading... why hasnt anyone ever went further into the developement of a recoil operated rifle?

The Johnson was deflated because it was going to be sold to the Dutch, but then the Japanese came and blocked it, so they had 20,000 rifles sitting around with no customers. They gave the guns to the Marines and the private market. The gun was meant to be issued to Dutch forces, but Japan got all jelly and took over their islands, thus ending the deal. So therefore, the Johnson M1941 was sold in the civilian market and also used in some numbers by the USMC. It was hardly a prototype, being seriously considered for military adoption and having a production run of 20,000 units. It lost to the M1 Garand because the Johnson's barrel would retract when you stabbed with the bayonet.

 

[Gtscotty]

There is a 1911 manufacturer that can gurantee 50 yard accuracy of 1.5" for 1500$.

That's interesting, but I'm not sure what a pistol with a mechanical accuracy of 3" at 100 yds has to do with the accuracy of reasonably priced recoil operated rifles. I bet for $1500 you could buy a gas impingement AR pistol that will shoot a group half that size at the same distance. Regardless, I think we are getting into an apples and oranges situation again.

 

[Elkins45]

I have a Marlin Camp Carbine in 9mm and the bolt is a fairly big chunk of steel with a relatively stiff spring. It's a straight blowback design with the barrel rigidly attached to the receiver. AFAIK it's the only blowback centerfire rifle I've ever encountered.

Wonder how heavy the bolt would need to be to build a straight blowback rifle in a powerful centerfire caliber like 30-06? I suspect you would need some serious mass to tame that sort of recoil impulse.

 

[jerkface11]

I can personally attest that the perceived recoil of a remington 81 in .35 Rem is extremely unpleasant and snappy.

That's odd I don't find mine unpleasant at all.

 

[Matthew Courtney]

The bolt does not move until after the bullet has left the barrel with any gun design.

Patently untrue. Most bolt's/breeches stay locked until the bullet leaves the barrel, but most(if not all) of them move the instant the powder is ignited. With recoil operated firearms, the barrel moves with the bolt, which complicates accuracy.

 

[68wj]

Patently untrue. Most bolt's/breeches stay locked until the bullet leaves the barrel, but most(if not all) of them move the instant the powder is ignited. With recoil operated firearms, the barrel moves with the bolt, which complicates accuracy.

In a gas operated weapon, the bolt does not begin to move until after the bullet has passed the gas port and the pressure begins to manipulate the cycling mechanism, relatively long after the powder is ignited. You can also see in many recoil operated firearms how the bolt and barrel remain locked together until a certain point. All of these variables are manipulated through weapon design (timing, tension, mass, etc).

Watch the first few seconds of this pistol here: http://www.youtube.com/watch?v=Rqu9jCuR5P0

 

[jason41987]

i think when you guys talk about accuracy of the recoil operation losing accuracy due to the moving barrel, its not so much the barrel moving before the bullet leaves the barrel, as much as its the likeliness of the barrel not returning to perfect zero every time would be my guess...

unless a chamber could be made to move independant of the barrel... which it could very well be made to do, then it seems like delayed blowback or gas is the way to go for a rifle with a goal of 1 to 1.5MOA in mind

 

[Sam1911]

...its the likeliness of the barrel not returning to perfect zero every time would be my guess...

unless a chamber could be made to move independant of the barrel

Either way, any movement of the barrel or portion of the barrel that is independant of the sighting mechanism, or which has the potential to alter any critical (or even secondary) relationships between the parts of the rifle from shot to shot is the antithesis of the principles of building a precision rifle.

FWIF, the Barrett M82 is not known for being especially accurate, compared to other styles of .50BMG rifle. In fact, Anzio builds a stabilization system to try and help improve things by controlling/limiting barrel movement. All in the attempt to try to bring up the precision of that system to something more like a bolt-action rifle.

 

[jmorris]

The only specimen I have is the 1919 and would say the limit is how far you can haul it.

There is a 1911 manufacturer that can gurantee 50 yard accuracy of 1.5" for 1500$

I have SV's that shoot one hole groups at that distance but at twice the cost. What's the point though, that kind of accuracy is no problem for a 1919 either and more to the point of the thread.

I have a Marlin Camp Carbine in 9mm and the bolt is a fairly big chunk of steel with a relatively stiff spring. It's a straight blowback design with the barrel rigidly attached to the receiver. AFAIK it's the only blowback centerfire rifle I've ever encountered.

There are a lot of centerfire pistol caliber carbines that work the same way, the 9mm AR being a good example, for this thread, as all rifle chamberings use the gas system.

If you wanted a rifle round to work the same you would need to add weight or spring. You would also need to add a hydraulic jack system to rack the bolt if you simply added spring tension.

 

[.45Guy]

Wonder how heavy the bolt would need to be to build a straight blowback rifle in a powerful centerfire caliber like 30-06?

~27 pounds if I recall correctly. (M2 ball)

Really though, everything else aside the reason that recoil operated longarms fell to the wayside is simple economics. I love my 8s and 81s, but I don't foresee anyone bringing such a complex design back into production anytime soon.