One of the more interesting (and rare!) variations on John Browning’s iconic 1911 automatic pistol is the Obregon. Developed in Mexico in the mid 1930s, this pistol uses a frame nearly identical to the stock 1911, but has a completely different locking system. It uses a rotating barrel, like a Steyr 1912, instead of Browning’s tilting barrel system. The Obregon has several other changes from the basic 1911, including a magazine safety and a combined single-piece slide stop and manual safety.
Somewhere between 800 and 1000 Obregon pistols were manufactured in the 30s. They were intended to compete for a Mexican military contract, which they failed to garner. We are much obliged to Eric for letting us take his beautiful example of the piece out to the range:
While this particular Obregon gave us some trouble (ironically, it didn’t like Aguila ammo made in Mexico), we think the design elements are overall pretty clever. In fact, the Obregon may be one of the safest pistols ever designed, at least on paper. I can’t think of any other designs that incorporate a manual thumb safety, a magazine safety, AND a grip safety.
We do also have a copy of Obregon’s US patent (granted in 1938), which unexpectedly addresses only the gun’s controls; the rotating barrel is not mentioned at all:
US Patent 2,115,041 (A. Obregon, “Automatic Loading Firearm”, April 26, 1938)
The rotating barrel was probably covered by patents on the Savage auto pistols.
There are at least a couple (probably more) patents before Savage’s delayed blowback version.
At least one of those is Browning’s US 580,925
The Two preceding US patent numbers are for Browning auto pistols too
580,924 is for the swinging link and combined slide and breech block which evolved into the 1911
580,923 is like something out of the Burgess Shale; a gas operated toggle action pistol (I know the book of Mormon forbids alcohol and caffeine, does it say anything about mushrooms, cacti or weed?)
Roth and Krnka also seem to have been busy with rotating locking systems for auto pistols around 1900 and before
One more thing. Did you find it to be more accurate than the Browning tilting barrel design?
In theory it probably should be, but we didn’t do any shooting for groups so I can’t say from experience.
Savage 1907 is little different animal… it does not have separate cam in frame but directly in slide. Its action is therefore rather abrupt. The Obregon is definitely slick design and it is pitty, there are just few in existence. It appears it is closer by its conception to Mauser design from earlier 20’s (patent granted to eng.Josef Nickel) which was utilised on Czech army issue vz.24. The inline rotary action pistols are quite rare (part of Berettas and couple of others) and are generally well regarded by shooters.
In Moderne Weapon B&T MP9 (Former Steyr TMP), Cougar by Berreta Groupe (Stoeger – turkish made), Px4 by Berreta, K100 (STI GP6) by Grand Power (Slovakia) but you could found same in old stuff Like MAB P-15 (French) or in Steyr-Hahn ….
If I remember correctly, in the Steyr-Hahn M1912 pistol designed by Konrad Murgthaler, the barrel is kept locked when the bullet travels through the bore.
As for the Obregon, thanks a lot Ian! That’s a really rare pistol you got to show us and test fire. The specimen seems to be in pristine condition. Besides, it is blued; most of the examples I saw (only in photos, never handled one personally) had what looked like parkerized finish.
I wish Ian, the Forgotten Weapons crew and all the readers of this blog a Happy New Year!
“..the barrel is kept locked when the bullet travels through the bore.”
They are (those of locked actions) all like that, at least theoretically intended so. Weapons for cartridges who’s impulse can be opposed by inertia of slide/ bolt mass only do not need locking. All pistols for 9mm Para and above are positivelly locked (with exception of those held ‘closed’ by gas pressure and some oddities).
Happy New Year to you and all at FW! Keep on doing good work!
Generally correct, though there are some big heavy 9mmp pistols, with brutal recoil springs which are entirely blowback;
and more through crap manufacture than design, the Rogack pirate copy of the Steyr GB
Earlier Astras and the Campo Giro on which they were based were chambered for the 9mm Largo (= Bergman Bayard) roughly equal in performance to the .38 ACP
Thanks for your note Keith. The Astra is quite well known (it has seen action during Spanish civil war and was exported as well). It is my understanding that is actually as you say of plain blowback design, but still bit puzzling given its size and weight. Would be nice if Ian could get hand on one and to demonstrate it. The VP70 had implementented in it gas delay, similarly as Steyr GB, I believe. They are definitely (nearly) forgotten weapons.
The P7 is gas delayed (or gas buffered) the VP70 was a big ugly blow back, in the civilian version it was double action only, and with a plastic receiver, something like a striker fired Walther PP on steroids, after bad plastic surgery.
The version for the military market came with a detachable shoulder stock, with that fitted it would fire 3 round bursts.
I don’t know if they got any military sales, the only one I ever saw was on the British H&K importer’s stand at a trade only arms fair in London, around ’81 or ’82, when they were trying to get rid of them to us civilians (Yep, H&K; because you suck…)
If it had come 30 years later, it might have sold quite well.
Yes, Danny, of course. Keith, to the Astra “puros” (cigars, in Spanish jargon) 400 and 600 one should also add their predecessor, the Campo-Giro Modelo 1913 and Modelo 1913-16.
I think R.A. is talking about the claims that the bullet traveling through the bore is keeping the barrel from rotating, due to the direction of the rifling.
Not sure if there’s any truth to that, but I’ve read it before.
Yes it is as you say: if gun’s rifling is RH which is typical, the cam has LH helix. This would force barrel against unlocking (kind of crawling forward instead of rear). In reality though the bullet is out of barrel before unlocking commences. You can verify it by factoring mass and velocity for bullet vs. moving parts (there is some idle travel before turning starts). Something like .04″ of idle movement is enough.
That’s the first time I’ve seen more than just a grainy photo of an Obregon.
a few questions
The unlocking cam that sits on the rod /peg in the receiver, below the barrel. in the locked position, is that cam block slightly foreward on the rod, so that it can slide straight back for a short distance before unlocking begins?
is the receiver cam simply loose to allow dis assembly?
From the locking lugs on the bushing, it looks like the grooves for the barrel locking run all the way to the front of the slide (apart from the ring cut in them for the bushing to seat), that wasn’t clear in the video, could you confirm please?
Following from that, I’m guessing that the lugs on the bushing are shorter, back to front than the lugs on the barrel, to stop it from rotating and snagging in the bushing seats?
Is one of the grooves a different size to the others, to ensure that it can only be assembled so the barrel indexes correctly?
The unlocking cam sits flush back against the frame – as best I can tell it doesn’t have any free travel before it starts the barrel rotating.
The cuts for the locking lugs do run to the muzzle, so the barrel can be removed out the front of the slide.
The lugs on the barrel bushing are significantly shorter than the barrel lugs, although there isn’t enough travel in the slide to get the barrel lugs that close to the front of the slide.
I don’t recall if one of the barrel lugs is a different size form the others, but the unlocking cam on the barrel can only be assembled in the correct orientation, so that does the same thing as having an odd-sized lug.
Thanks for this informative post.
Rotating Barrel Lock, though first used by J.M.Browning on a prototype pistol,
was developed mostly by European designers and, with a very different way, by
another American genius named Elbert Searle.
Searle’s pistol which produced by Savage, used no recoil power to unlock the barrel but depended upon the exhaust of the counter force of barrel rifling against to
the bullet pass. The rotation was about five degrees and since the breechblock being
a seperate unit also rotationaly mounted at rear of the slide, the locking effect of barrel rotation was somewhat reduced. Searle’s U.S Patent Numbers were, 804985
and 936369 for this pistol, and Searle’s locking effect accepted very weak at that times, but managed to overcome a .45^caliber bullet during 1906 Government Tests.
Succesfull European Rotating Barrel Lock approaches began with Steyr 1912 pistol
which known as designed by Karel Kyrnka. This pistol had used the recoil force for
unlocking and had camming slots cut directly on the receiver resulting somewhat a
cumbersome take down. A young Mauser Engineer Josef Nickl, had remedied this
difficulty with a removable cam block going out with barrel during the field strip
and this concept was used at all recoil operated rotating barrel pistols after
Nickl’s CZ 22, up to that time, including modern Beretta pistols and even Chinese
CF98 Military handgun, with only exception of K100 pistol designed by Jaroslav
Kuracina which also patented in the U.S. With the serial No. 6826997. Obregon, also
was one of the fidel followers of Nickl System.
French had bought huge amounts of Savage pistols during WW1,and the unreciprocating
rotational barrel lock of Searle was used on a pistol, MAB P15, successfully, with
Josef Nickl’s way of dismount process at a fraction after the half of last century.
This pistol used a fifteen degrees of rotatement for unlocking and though not
mentioned, it used the “Satitic Friction” principle of different kind of metals
sticking together under high pressures which also was a subject of concept, “Blish
Lock” used on the Thompson submacineguns.
Rotating Barrel Locks are considered, at least, theoreticaly, better than tilted
barrel types by cause of having no vertical mmovement, but in practice, and
especially on using tactical accecories like sound suppressors, it is accepted
inferior since having a tendency to screw off the tackles mounted over the rotating
Thanks much for this posting, I’ve been intrigued with this pistol since I first saw it, and have long wanted to take and build a copy. I always assumed the rifling would be considered with the force it would impose on the lock, and have considered this lock little different than those such as the mg-34 and so many others which rotate with a lock which only begins rotation after barrel movement, and relying on “threads” as a lock, and not as the driving mechanism.
I have worked with and owned several .45’s which have been “accurized”, all requiring barrel bushing clearance altered, lock up cleaned and polished, rails tightened, and have considered all these techniques relative to the Obregon and long considered it likely they would be even more effective on it because the barrel remains in line, un-tilted.
Great article, very happy to have all the information so many others have added as well.
I am really intrigued by the safety/slide hold open. If your website would ever consider producing videos you should show this and demonstrate its operation. Yes, this is sarcasm. You totally dropped the ball here. When you were talking about it and not showing it, l was in total shock disbelief and suspense. How does this work?
Take a look at the patent description – it covers this element of the design.
Yes I am sure it does. If you ever get the chance to shoot (pun intended) more footage of the Obregon please add some video of this function. Patent design doesn’t let you know how it would sound or feel, your videos should.
Obregon Patent description is rather short and confusable. But Safety Lever working
is simple. It is a multifunctioned part as; acting a TakeDown Key Piece as holding
the Cam Block carrying the barrel thereon, as acting a Slide Stop cooperating with
magazine follower with an integral lug on path thereof, and as acting a Sear Blocker
when on its upper position with aid of another integral lug protruding inward in
front of a fore protection of sear and verticaly acting as to block or release its
forward rolling motion. An upward lug on the rear of safety lever as cooperating
with recesses cut in the slide as in line with its upward motion, also acts to arrest the slide movement on foremost and rearmost positions.
There is no description relating to the Rotating Barrel Lock construction in Obregon
“The VP70 had implementented in it gas delay”
This is not 100% true, but suprisingly, you are on right track !
Since VP70 uses unique system of barrel grooves and lands, where the grooves are cut much deeper than on regular 9mm para barrel, so the gas flows around the rotating bullet that travels the muzzle, thus obtaining the lower bullet velocity (lower than 300 m/s) and by the law of physics, less force is projected on it’s blowback slide, so the slide does not need to have extraordinary mass, and/or the spring unusualy strong. Also, the barrel is not too long to begin with.
So you end up with a bullet velocity and energy specifications that are somewhat close to 9mm Makarov or .380 ACP, and this is not much known when some articles describe this unique and “revolutionary” pistol, that had equal numbers of good and not so good features-mostly experimental, decidingly ending to be not extremely sucessfull in general selling.
I always wondered why they didn’t rework the design to be both SA/DA, when they saw that notoriuosly heavy trigger pull was scarecrow for buyers. To put my sentiments on the side, still, you can’t escape from the fact that you get a gun that kicks probably more than your average “wonder nine”, but sends to the target underpowered rounds almost equal to 9mm Makarov. So it’s only horses left in the stable now are unusually (for 1970s) large magazine capacity (which was, I suppose, pain in the ass to utilise in semi auto practice, since nobody was happy to strain his finger pulling it like crazy 18 times and probably thinking in process: “God, when will I finally spend this damn magazine, and rest my finger”) and overall simplicity of construction and disassembly, not to mention futuristic looks that adds the “coolnes”, but unfortunately that does not change or upgrade the gun in any other way.
Of course to begin with, one must have in mind that DA mode only was dictated by idea of simplification of manufacture and usage and safety by serving the role of some kind of resistance-partisan-peoples(volk) pistol, carried and used along burst mode “stock”, clandestinely in would be soviet invaded countries.
Looking forward on in-depth review here one day, of course.
“I can’t think of any other designs that incorporate a manual thumb safety, a magazine safety, AND a grip safety.”
Um, Colt .32 and .25 Pocket Autos? H&R .32 Auto? 😉