Friday - March 13, 2009

double porn

The Boberg XR-9 pistol is a short recoil operated, locked breech pistol. It uses rotary barrel locking with a single massive locking lug on the top of the barrel, which engages the slide when in battery. The trigger is of double action only (DAO) type, hammer-fired. The heart of the two-stage “pull - push” feed system is the claw-shaped loader, which is pivotally attached to the slide. When slide is in forward position, the claws are lowered under the barrel breech area, gripping the base of the topmost cartridge in the magazine. When slide is cycled (manually or under the recoil of the previous discharge), the claws pull the cartridge rearwards from the magazine until it is clear; at the end of recoil stroke, claws are lifted to place the cartridge to feed position. On the closing stroke of the slide, cartridge is pushed into the barrel chamber, and the feed claws are lowered to grip on the following round in the magazine. Obviously, such system requires specially designed magazines and is somewhat more complicated than standard “push forward” feed system encountered in most other firearms, including pistols. The benefit of this system is significantly increased barrel lenght, which is especially important for compact pistols with shortest possible barrels.

To quote the designer: “The chamber does not have to be sloppy since the cartridge doesn’t have to come from the bottom and “wiggle” into the chamber like on a traditional feed mechanism. Tighter chamber clearance yields about 4% more kinetic energy with 115 grain bullets, and 12% more energy with 147 grain bullets compared to other same-barrel-length guns with the standard sloppy chambers. More power channeled forward instead of backward...”

The mechanism is actual quite similar to the one on a Browning machine gun. Cartridges are held by very light spring pressure in a magazine. Instead of coming out forward like cartridges do in a regular magazine, these come out to the rear.

When the pistol is fired, the bullet travels down the barrel, and spins in one direction because of the rifling in the barrel. You can’t phool physics: this creates a torque in the opposite direction. That torque spins the barrel along its axis a little, perhaps slowed down by a helical spring, and that turning unlocks the barrel from the slide. The bullet is now out of the barrel, but inertia is still pushing the cartridge case back against the bolt face area of the slide. So unlocking the barrel lets the slide ... slide. It goes back over an ejector, spits out the empty case, and is brought to a stop by the compressed mainspring. As the slide begins it’s rearward travel, a little clothespin-like spring thingy pulls a new round from the magazine. At the end of the slide’s rearward stroke, this claw pivots up and raises the fresh cartridge into position. As the slide moves forward, the cartridge is fed straight into the chamber. No feed ramps needed. No slop in the end of the chamber like on most semi-automatics, to give the round a bit of spare room to “go around the corner”. Which means less pressure wasted on expanding the brass, and more of it spent pushing the bullet. Finally, at the end of the forward stroke the slide pushes a little cam upwards which rotates the barrel back, and the loaded round is now locked into battery, ready for the next pull of the trigger.

There is a most excellent 2 second animation, along with several videos of the gun firing, and lots of pictures and information at the Boberg website, Boberg Engineering.


Early reviews are quite positive. The pistol is accurate and reliable and oozes quality.

Ok, why all the fuss? What makes this thing so special, considering the mechanism concept is over 100 years old, and the rotating barrel idea is borrowed from Beretta and other modern designs? 

First reason: Almost all semi-automatic pistols put the barrel above and in front of the magazine. The XR9 puts the magazine under the barrel. That means you get either a longer barrel for a given length pistol, or a shorter pistol for a given length barrel. Either one will give you at least an inch more barrel than you can get in a regular pistol. And a longer barrel means higher velocity. More velocity means more power and less flash. Very short barreled guns, like the tiny ones you’d want for a pocket sized CCW “mouse” gun, lose huge amounts of velocity because their barrels are really short.

Second reason: a pistol that uses a locked breech design is much stronger than one that is designed to use a blow-back, unlocked breech. This lets you use more potent cartridges, without getting a face full of still burning gunpowder gas.

Third reason: I think it’s bloody cool looking!!



Boberg is planning on releasing two versions of their new pistol. The “regular” XR9, which offers full sized pistol performance in a small sized package, and the “micro” or “shorty” XR9S that offers mid sized performance in a very small package. How small? This small:

The Ruger LCP has very tiny low sights. The XR9 has typical “low” sights; my guess is another .1” - .2” could be shaved off the height by using lower sights. So the Shorty winds up being shorter than the loose-it-in-your-pocket small LCP, but about half an inch taller, and a few ounces heavier. The Standard is just over half an inch longer. But either model gives you one extra shot, has a longer barrel, and uses the 9mm cartridge, which is nearly twice as potent as the .380. Especially when you have enough barrel to stop losing velocity. Oh, and the grip is steeply angled, very much like the P-08 Luger, which gives it nearly perfect ergonomics and a very natural hand position. That steep grip puts a good chunk of the upper back over your hand, so the balance should be very neutral.

Downsides? It isn’t on the market yet, and it is going to cost what most quality pistols cost - $800 - $1000. The company is in start-up, so expect the first couple of years to be, if not a bit rocky, then at least a little gravel strewn, just like any other start up.

More upsides? Mr. Boberg wasn’t overly specific in his patent, so his action could be made for a rifle as well. How about this idea applied to a bullpup action? Talk about minimum length guns! Or he could turn out a full size pistol, perhaps with a double stack magazine, that has a 7” barrel instead of the typical 5” one. Which would add another 100fps or so to the velocity of any of the more potent pistol cartridges, like the 10mm Magnum.

This is the first actually new pistol design I’ve seen in ages. Looking at it, realizing how simple it actually is, gives me such a Duh Moment that I wonder why JMB didn’t figure this one out 100 years ago.

Posted by Drew458     on 03/13/2009 at 09:12 PM   
Filed Under: • Guns and Gun Control • Science-Technology •  
• Comments (9) • Trackbacks(0)  Permalink •  

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