Flared pistol barrel

[imp]

I've noticed some pistols have barrels that have a constriction and then a flare on the outside near the muzzle. The popular models that come to mind are 3rd gen Smith and Wesson 9mms, and keltec autos, and I know there are more. What is the purpose of this shape? http://http://media.midwayusa.com/productimages/880x660/Primary/494/494979.jpg

 

[Bill DeShivs]

The shape allows a tight fit in the barrel bushing for accuracy, and allows for clearance when the slide retracts.

 

[Old 454]

I believe there called Bull barrels

 

[jar]

One of the more extreme modern examples I'm aware of is on the Sig P290RS. In the first picture you see the 380 version in blue and the 9mm Para in red.

And then with the slide locked back to show the barrel flare.

 

[Jim Watson]

The muzzle of the S&W and Keltec are shaped to allow the barrel to tip up and down to lock and unlock.

The Sig shown has a flared muzzle to fill the slide bore. Lots of shortened 1911 types do because the barrel comes out to the front and the locking lugs end up too close to the front of the slide for a bushing.

 

[Sluggederbore]

I thought the flare was to use them like a blunderbuss with shotshells.

 

[44 AMP]

I thought the flare was to use them like a blunderbuss with shotshells.

I will assume this is sarcasm.

The flare of a blunderbuss was widely thought to spread the shot, but it really doesn't. What is does do is provide a nicely large "funnel" on the end of the barrel to make loading in a hurry or on the move easier.

 

[tipoc]

The OP here kindly offered us a pic of what he was asking about which is similar to this one on the 3rd Gen S&W semis...



Bill De Shivs answered that one correctly:

The shape allows a tight fit in the barrel bushing for accuracy, and allows for clearance when the slide retracts.

It's not a Bull Barrel that's different but has similar results. We see this type most often (maybe always) with fixed bushings as distinct from removable bushings like the 1911.

tipoc

 

[SIGSHR]

IIRC that design allows a better fit without a separate bushing.
A bul barrel is a heavy barrel of the same diameter from muzzle to frame-the heavy barrel S&W Model 10 or M-58, e.g.

 

[tipoc]

A bull barrel in a revolver is a different creature altogether from a bull barrel in a semi.

In a semi it's a barrel that has a diameter at the muzzle end that mates to the slide and not to a bushing. It does away with the bushing altogether. It is substantially thicker and heavier at the muzzle end than towards the chamber.

You can see that clearly in this early Detonics Combat Master. This was one of the first guns to use a bull barrel. In this case the barrel behind the muzzle was cut and shaped to a smaller diameter. I usually see this in compact and sub-compact guns.

Below is a vid that explains it some. It's too long so skip to the 1 minute mark.

https://www.youtube.com/watch?v=XtXrol3gmYQ

tipoc

 

[T. O'Heir]

A blunderbuss didn't use shot shells. Usually didn't use shot either. Bits of metal. Stones or gravel and whatever else was laying around.
"..."funnel" on the end of the barrel..." Yep. Made 'em scarier looking too.
"...It's not a Bull Barrel..." Exactly. It's about clearance upon cycling and the fit to the bushing when in battery. We used to machine 5 thou off the body of 1911/1911A1 barrels leaving the last half inch alone for the same reason.

 

[briandg]

Just to add something, if you look at some of the available handguns you will find some slides are relieved where the barrel meets the slide. This allows the barrel to tip down unimpeded, just as the ball at the end of the mentioned barrel does.

My bodyguard is tapered this way and I believe that the glock is as well.