Rotating barrels?

[Spats McGee]

I know (or think I know) that Beretta uses a rotating barrel in the PX4. I was just reading The Firearm Blog's article on the Glock 46, which uses a rotating barrel design.

I'm asking you TFL experts to educate me. Why use a rotating barrel design? What are the alleged benefits? Downsides?

Thanks,
Spats

[GarandTd]

I'm no expert by any means, but I think they transfer recoil in a more linear fashion and keep the barrel in line with the path of the bullet as opposed to the barrel tilting up. I think this would offer better accuracy and follow up. If I'm correct, I would consider those the pros. If I'm wrong, I'm sure I will be corrected. Not sure on the cons, but am interested to hear more about the system.

[Walt Sherrill]

Originally Posted by GarandTD

I'm no expert by any means, but I think they transfer recoil in a more linear fashion and keep the barrel in line with the path of the bullet as opposed to the barrel tilting up.

As I understand it, in a properly fit and functioning Browning Locked Breech Short Recoil design semi-auto, the bullet typically leaves the barrel before the barrel begins to unlock from the slide -- the slide has moved only small fraction of an inch before the bullet is gone. But, even then, barrel tilt shouldn't be an issue, as long as -- if it occurs -- it does so consistently.

Related to YOUR POINT, however, is that with the Browning design, the barrel moves both back and down and then must return to the starting position, working in several planes. That would seem to suggest (at least to this non-engineer gun enthusiast) that getting a consistent barrel to sights lockup MIGHT be more easily accomplished with the rotating design.

That said, I've never seen any test results comparing one design to another with equally well-fitted guns, nor have I seen serious enthusiasts using the rotating design for super-accurate guns. That may simply be because I haven't looked enough... It remains "theory" for me.

[5whiskey]

Why use a rotating barrel design?

I honestly have no clue why they would do this. This is actually quite the surprise from Glock. Not professing to be an expert but I think even experts will be split as to the alleged benefits of a rotating vs tilt barrel. There will be conjecture of greater accuracy potential with a rotating barrel. I'm with Walt, it looks like it would be easier to achieve ultimate accuracy with a rotating barrel design... but many unquestioned contenders for most accurate pistols (Sig P210, S&W 952) have a tilt barrel lockup. Also, of the current rotating barrel designs (Beretta PX4 probably being the most used), accuracy seems to be more or less on par with quality tilt barrel designs such as CZ, 1911s, etc. Also most will not argue that the tilt barrel design aids in feeding reliability and is basically easier to get right during manufacturing.

I will propose one theory. I do believe that a rotating barrel can be designed to increase lock time beyond what would be possible with the tilt barrel system. This, theoretically, may allow you to up the durability of the firearm while shooting stout loads. Maybe, this is speculation on my part so maybe someone else can chime in. I can't really think of many other reasons to go astray of the system that has made Glock a LOT of money over more than 30 years.

[Jim Watson]

It amazed me that Glock would change horses in midstream.
It is hard to see what a rotating barrel would do for the Bavarian cops that a Browning tilt lock doesn't.
A little lower bore axis like their discontinued P7s?
Could not devise a no-trigger takedown for a Gen 5?

Linear recoil, maybe, but how about torque reaction? I know people who say they can feel the torque of the bullet spinning up, what about rolling the whole barrel.
Better accuracy, not a chance.

I figure the early guns like Roth Steyr, Steyr Hahn, and Savage were honoring the very comprehensive Browning/Colt/FN patents, but those were long gone by the time of the Obregon, PA15, AA2000, Cougar, and PX4.

[pblanc]

The rotating-barrel breech lock-up mechanism is certainly not a new phenomenon with the Beretta PX4 Storm. Only the full-size and compact PX4 use the rotary barrel lock-up, by the way. The subcompact uses a traditional tilt barrel design with a barrel hood to frame lock-up.

Beretta, and later Stoeger Cougars, utilized the same breech lock-up design but were all-metal pistols available in DAO and DA/SA designs. They have now been discontinued but might be thought of as precursors to the PX4 Storm.

Grand Power also imported the K-100 Slovakian design. The Colt 2000 All-American was a rather notorious rotary barrel design that might have served to discourage other makers from introducing similar lock-up mechanisms. It was based on a design by Reed Knight and Eugene Stoner and Colt brought it to market in 1991 with polymer and aluminum frames as a high capacity 9mm pistol to compete with Glock.

The execution of the Colt 2000 was terrible. It was unreliable, not durable, and had a terrible double action only trigger mechanism.

The Brugger & Thomet MP9 submachine gun also uses a rotary-barrel breech lock-up mechanism.

A non-tilting barrel lock-up allows for a slightly lower bore axis. The most commonly mentioned potential advantage of such a system is that it mitigates perceived recoil better than a tilt-barrel lock-up design. I don't know it this is true or not, but I do own two Beretta and one Stoeger Cougar, in 9mm .40 S&W, and .45 ACP and they all seem to be soft-shooting so perhaps there is something to it.

Most people feel that rotary-barrel lock-up designs require more attention to proper and more frequent lubrication, and I believe this to be true. Some people have complained that these designs produce a kind of torquing or twisting effect with recoil. That seemed to be a common perception with the Colt 2000. I have never experienced any such phenomenon with the Cougar design.

[cslinger]

More linear/less perceived recoil with heavier calibers. In 9mm......ehh I don't really see it.

Theoretically lower bore axis.....but again I think this is getting into the minutiae.

They do require more attention to maintaining IMO. Grease on the rotating surface/lugs. Not a big deal but more then "I just lube my Glock with dirty swamp water"

I have a PX4 that I very much like and have never had a problem but it's not used hard. It is in 9mm so that linear recoil impulse might be able to be felt a tiny bit but honestly in 9mm it's a non issue. Now in .40 and .45 there is a noticeable reduction of perceived recoil.

Personally I have NO IDEA why Glock would do this. I mean yeah the HK P7 has a super low bore axis but really you cannot train your folks to shoot the "exceeding high bore axis " Glock 17???? And if your Glock you cannot figure out a fairly simple takedown sans trigger pull/striker deactivation? I mean slap a P99esque decocker on there and call it a day.

I am not bagging on rotating barrels I just don't understand the fundamental operation change to chase a contract.

[lee n. field]

I wonder if the Glock 46 might not be something like a "concept car". It's there to try something out, and gauge consumer interest.

[muzzleblast...]

Let's not forget the Mauser M2:

http://www.genitron.com/Handgun/Maus...0-SW/Variant-1

[TailGator]

I was as surprised as anyone that Glock was playing with a rotating barrel design. It seems like quite a departure from form for them.

I have a PX4 Compact in my safe. (It belongs to my daughter but she lives in NYC now.) It is notably soft shooting, and I thus give some credence to the claim that the rotating barrel system decreases perceived recoil; I will not claim the ability to separate out the effect of the rotating barrel from other factors like grip, however.

I will also agree with the post saying that the rotating barrel may require more attention to lube than other designs. I experienced a lock up in the gun when it was dry (my bad) that resolved when I was able to push the barrel rotationally.

[mete]

It's been around for about 100 years !! It's not a "locked breech" design but a " delayed blowback " design ! They actually reduce felt recoil as the recoil is spread out over time .
Of the basic designs the highest felt recoil is a 'blowback ' next a 'locked breech ' then a 'delayed blowback'
I demonstrated a Remington M51 [delayed blowback], Mauser HSc [blowback ] and a CZ 24.All the same weight , all in 380 . The difference in felt recoil was obvious !!
That these three types of mechanisms were found in 380 may be that at the time there was confusion as to whether or not a 380 had to have more than blowback !
The best of the delayed blowbacks I've fired is the HK P7 !! in 9mm !

[DaleA]

I demonstrated a Remington M51 [delayed blowback], Mauser HSc [blowback ] and a CZ 24.All the same weight , all in 380 . The difference in felt recoil was obvious !!

Very cool!!!
Because:
1. You had all three guns.
2. You knew what action they used.*
3. You were able to post here and provide an actual example for us.
Thanks!

*One of the Amazon reviewers of the book "Tommy Gun: How General Thompson's Submachine Gun Wrote History" found this error: the author said the Browning Automatic Rifle (BAR) operated on the blowback system. This is incorrect. So even a guy writing a book on guns doesn't always know this stuff.

[GarandTd]

This is a great thread!

[gc70]

Originally Posted by Spats McGee

Why use a rotating barrel design? What are the alleged benefits? Downsides?

The Firearms Blog article is based on an article from the German Magazine DWJ. The original (in German) DWJ article is here, starting on page 68.

The DWJ article has some tantalizing clues about the reason for the rotating barrel. (Excuse the Google translation; my German is very, very old and rusty).

The pistol is extremely comfortable because of the favorable grip angle, the small distance between the upper edge of the hand and the bore axis (low impact), and not least because of the slow speed unlocking. A minimum unlocking stroke is to be noted.

Advantages of the new gun model. The first important advantage is the symmetrical, bore-axis arrangement of the opposing locking nipples. This is beneficial if you use higher-performance ammunition.

A further important aspect is the function-safe control of the locking input, which is typical for the G46, via a control curve in the closure body ("carriage"). The barrel has no weakening through a feed ramp in the cartridge bearing area. The cartridge sleeve is thus fully enclosed.

However, the real reason for the rotating barrel is probably lurking in the German police TR/ER "Pistolen" requirements (checklist here - in German).

[carguychris]

Originally Posted by lee n. field

I wonder if the Glock 46 might not be something like a "concept car". It's there to try something out, and gauge consumer interest.

I seriously doubt that. Glock has staked their marketing reputation on NOT substantially changing the core product. Recall the motto "Perfection."

Originally Posted by gc70

...the real reason for the rotating barrel is probably lurking in the German police TR/ER "Pistolen" requirements...

^^^This.

I don't read German, but I strongly suspect that the contract requirements either require a rotating barrel outright, or effectively prohibit a tilting barrel.

[wild cat mccane]

Get your PX4 now before it goes back up

[muzzleblast...]

Originally Posted by mete

It's been around for about 100 years !! ...

The oldest one I know of is the Browning design going back to a 1897 patent.

[wild cat mccane]

Using Google translator, rotating barrel it is not a requirement.

Would be stupid, since there is only the PX4....

[JohnKSa]

It's not a "locked breech" design but a " delayed blowback " design !

Every rotating barrel design I've had the opportunity to examine has been a locked breech design. The breech and barrel are locked together by one or more locking lugs until they move rearward sufficiently for the barrel rotation to unlock the lugs from the slide. No amount of force, short of deforming the slide or lugs will open the slide until the unlocking mechanism is activated by rotating the barrel.

That differs from a delayed blowback where the barrel and breech aren't actually locked together but there is some delaying mechanism which slows the opening of the breech compared to what would be experienced with a simple blowback.

The H&K P7 gas delayed blowback design is a good example of this type of action. There is nothing locking the slide closed, but upon firing, gas pressure in the barrel is diverted to retard the movement of the slide and thereby delay the blowback action.

Another example is the toggle action of the Luger. The breech is not locked closed, but the toggle resists the opening of the breech by presenting a considerable mechanical disadvantage to the forces pushing the breech open.

[Bart Noir]

While the Grand Power has been mentioned already, it is by no means a past-tense gun, either in Europe or here in the US of A. It is well made and is popular in competitive tactical type shooting in Europe. It is for sale in the US in a couple of sizes and it has the rotating barrel design.

My first rotating barrel pistol was a PX4 in .40S&W. It was noticeably softer in recoil than the several other .40-calibers I had owned, which were all Browning tilting barrel guns.

Since then I have owned a Cougar, more PX4s (2 sizes) and now a Grand Power Compact. All were in 9mm. The Px4 Compact and the GP Compact are still with me.

I think they are softer shooting even in the less powerful 9mm caliber. I always thought this was because of not having a barrel flipping up and down, but now you folks make me think also of the timing of the recoil pulse. Thanks for that idea.

While we won't be seeing it for sale, there is another rotating barrel pistol in use. The GSh-18 is a Russian gun which is popular with a number of police and military agencies in Russia, although it is not the standard Russian military pistol.

Bart Noir

[Jim Watson]

The Savage automatics with only 5 degrees rotation and depending on the Searle Effect to torque it shut a little longer might fall into delayed blowback.
The MAB R9, unlike its successor the PA15, had a cam cut that let the slide start back immediately the barrel started rotating, also another delayed blowback suspect.

[JohnKSa]

Interesting. I have not had the opportunity to examine those guns.

The PX4/Cougar, the Grand Power and, from what I can tell, the Glock in the article all use a locked breech system. The Glock system appears to be very similar to the PX4/Cougar system which uses a "tooth" on the barrel and a separate locking block with a "channel" that the tooth engages to perform the unlocking operation.

I wish Glock had gone with the Grand Power system as it is lighter, more compact, and doesn't require a separate locking block.

[gc70]

Originally Posted by carguychris

I don't read German, but I strongly suspect that the contract requirements either require a rotating barrel outright, or effectively prohibit a tilting barrel.

The Ulm Proof House publishes a list of guns certified as meeting the German "TR" police requirements; none of the certified guns have rotating barrels.

While a rotating barrel is not an explicit requirement, some combination of requirements must have led Glock to its solution involving a rotating barrel.

[James K]

The best known example of a rotating barrel is in the common Steyr-Hahn (Steyr-Hammer) pistol. A rotating barrel is inherently more accurate than a tilting barrel design because it is more fully supported and its motion is straight back and forth with no tilting and fewer problems with barrel re-set when returning to battery. A down side is that the locking lugs make the barrel larger in diameter, something that is obvious in the PX4.

But the rotating barrel is definitely a locked breech, the same as a 1911, just a different way of achieving that. (Some say it is a delayed blowback since the barrel begins to rotate when the slide moves. True, but so do most "locked breech" pistols.

Jim

[5whiskey]

Delayed blowback is different from short-recoil... Short recoil always involves some form of locked breach, while delayed blowback doesn't (delayed blowback may have a locked breach but usually doesn't).

All rotating or tilt barrel pistols in common use are short recoil operated. I'm sure there may be an oddball out there somewhere, but it will not be in common use.