Cylinder Gap?


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LJ-MosinFreak-Buck
November 4, 2011, 08:31 PM
Okay, so honest (and probably stupid question) here. Why don't we see a modern "gas-sealed revolver?"

I know about the Russian 1895 Nagant revolver (I've had my hands on a couple, like the design), that's why I ask. I also know that the trigger pull is significantly higher than a revolver that doesn't push the cylinder forward and against the forcing cone (if that is the correct terminology).

What's the negative here? Cost prohibitive? Or are modern societys' trigger-fingers getting lazy?

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rcmodel
November 4, 2011, 08:47 PM
There is so little actual measured performance loss in a properly fitted revolver as to make a gas seal a useless & expensive proposition.

The Russian Nagant gas-seal deal came out well over 100 years ago.
It did nothing then except complicate things, and it wouldn't do anything more today.
If it did, all modern revolvers would be using a gas-seal design in one form or another.

Chronograph testing of revolvers and auto pistols of equal barrel & cylinder length vis chamber & barrel length give basically the same velocity.

There is more velocity variation in ammo shot to shot then there is between the two action types.

rc

MrBorland
November 4, 2011, 08:47 PM
I know little about the Nagant, but AFAIK, it was a solution to a problem that never existed - the gas escaping from the cylinder gap leads to a negligible loss of muzzle velocity. Also, I don't know if it's an inherent property of the design, but Nagants have to be reloaded 1 cartridge at a time.

In the end, a painfully slow reloading process, higher manufacturing cost, and a stiffer trigger trigger pull, and there isn't enough advantage to justify a more complex & more expensive mechanism with a higher consequent higher potential for reliability issues.

Just my $0.02.

LJ-MosinFreak-Buck
November 4, 2011, 10:23 PM
I was just curious. I like the idea of gas-sealing. Ignorance is throbbing here, but wouldn't it take away the risk of injury of holding the revolver in the wrong spot?

And I agree, I wish they had the cylinder on a crane (terminology?) that swung out for reloading.

MrBorland
November 4, 2011, 10:41 PM
Ignorance is throbbing here, but wouldn't it take away the risk of injury of holding the revolver in the wrong spot?

Largely another non-issue: ‹bermagnumboomers notwithstanding, the risk of injury is greatly overrated, IMO. Some of us even use a thumbs-forward semi-auto grip with no ill effects. ;)

bergmen
November 4, 2011, 10:41 PM
There is so little actual measured performance loss in a properly fitted revolver as to make a gas seal a useless & expensive proposition.

The Russian Nagant gas-seal deal came out well over 100 years ago.
It did nothing then except complicate things, and it wouldn't do anything more today.
If it did, all modern revolvers would be using a gas-seal design in one form or another.

Chronograph testing of revolvers and auto pistols of equal barrel & cylinder length vis chamber & barrel length give basically the same velocity.

There is more velocity variation in ammo shot to shot then there is between the two action types.

rc

That is very interesting, I've always wondered about this. Some of my revolvers (Ruger Bisley, Blackhawk) have some daylight between the cylinder and the barrel (never measured it but looks like .005-.008 inches or so).

My Freedom Arms .454 Casull has less than .001 clearance (I cannot get a .001 feeler gauge leaf in there). The powder I use (W296) burns clean enough that it doesn't crud the front of the cylinder to the extent that it needs to be cleaned to assure smooth operation but I've only done 50 rounds max per session.

Dan

BCRider
November 5, 2011, 01:39 AM
Don't discount the cylinder gaps flash of pressure to do damage. A year or more back there was a good video on YouTube about a guy who used a semi auto style grip or a "rifle" like grip on a .357Mag revolver where his thumb was in the line of the gas "wing" from the forcing cone gap. It cut his thumb deeply as a stab from a combat knife.

I went to YouTube to find it again to link here but they've got some whimpy deal going where you need to sign in to a personal account now to verify that you won't get sick and chuck your cookies all over the dog. But the video is still there at;

http://www.youtube.com/verify_age?next_url=http%3A//www.youtube.com/watch%3Fv%3DtmEatEe4FbQ

I've also seen folks using a semi auto style thumbs forward grip on some videos in a recent thread here on THR. But frankly although they are long time shooters I feel that they are avoiding getting their thumb hurt more due to good luck than good planning. Even .38Spl when fully up to near max pressure will create a knife like gas "wing" from the forcing cone gap. That their thumbs are just stained rather than cut is due to the simple fact that they don't quite extend them far enough.

So just say "NO!!" to using semi auto style hand grip styles on revolvers......

PO2Hammer
November 5, 2011, 02:34 AM
You don't want to have your thumbs there, but there's no real loss of performance.
IIRC, someone did loose a digit with an improper grip on one of the big S&W super mags.

LJ-MosinFreak-Buck
November 5, 2011, 03:51 AM
That is unfortunate. But wouldn't a gas sealed cylinder reduce, or even eliminate this?

PO2Hammer
November 5, 2011, 11:13 AM
I think that takes us back to post #2.

rcmodel
November 5, 2011, 11:32 AM
Blowing your finger off with the barrel/cylinder gap gas takes some real doing to even get your fingers there.

And it is not a real concern until you get into magnum class and even higher pressure guns like the S&W .460 & .500 Mags. Getting your fingers in the way on them is even harder, because they are so darn big it is a long ways from the grip to the B/C gap.

Apparently, it is not a big enough problem that revolver manufactures even address it, other then recently with even more RED Safety warnings in the owners manuals.

It was an issue way back when though, when Colt thought revolving rifles would be a hot seller.
Turns out Cap & Ball chain fires are not all that uncommon.
And having your left hand out in front of the revolving rifles cylinder could be quite devastating if all 6 charges went off at the same time!

Now Taurus has reinvented the wheel with the Circuit Judge rifle.
But they are not cap & ball, and they have a Blast Shield built into the side of the gun.

rc

MrBorland
November 5, 2011, 12:08 PM
I agree with rcmodel (post #5). For the majority of revolver shooting, it's not a big issue. Here's a pic of the newly-crowned IDPA SSR World Champ and his grip. He's a big guy, and even with his thumb way out there (even further than mine), there are no ill effects, other than a sooty thumb. Note that the gas escaping really doesn't go down to the thumb, so much as to the side.

Still, I recommend putting your thumbs where ever you feel comfortable putting them. ;)

http://gunnuts.net/wp-content/uploads/2010/03/buckland-thumbs-forward-actionshootingpodcast.jpg

Mizar
November 5, 2011, 02:05 PM
The problem with Nagant gas-sealing system is that it uses a moving breech block to compensate the front shifting of the cylinder. It's a weak design suitable for low powered cartridges. If one wants such a system to withstand the forces generated by today's magnum cartridges he will end up with a heavy and bulky frame. Not practical at all.

Boris

P.S. BTW, the M1895 Nagant revolver is of Belgium origin.

Dnaltrop
November 5, 2011, 02:21 PM
I've worn the forcing cone down on a Model 10 from sheer volume (or at least the gap is significant enough)

It functions flawlessly, still accurate, but there is a 180 degree field in front of the gun that you risk being speckled by flaming powder and the odd bit of shrapnel if you stand too close to the side. I sure as heck make sure my fingers are nowhere near the front of the cylinder, and that with just .38 SWCs. My old man got his knuckles gouged when he walked up next to me a bit too close. Didn't even feel it, I just saw his hand start to trickle blood.

http://www.thehighroad.org/archive/index.php/t-391097.html old discussion here on the topic of Inadvertant excision of fingers via the fine surgical skills of Dr .460

Love the 1895, it's just not enough of a technical leap to be used today. There was a slight FPS rise, from the sealed chamber, but it's the difference between being hit by a 4000 lb car at 60 mph, and being hit by a 4000 lb car at 62 mph.

Got_Lead?
November 5, 2011, 03:13 PM
On the other hand, semi auto's can bite pretty good if you wrap your non shooting hand's thumb around the shooting hand. So both have caveats.

My Ruger securety six chrono's about 50 fps faster than my Smith Model 52 semi auto. Both are .38 special, the 52 with its solid barrel pushes a 148 grain WC at 720, while the SS-6 hurls them at 750 to 770 fps. Maybe just the extra couple of inches on the barrel.

rcmodel
November 5, 2011, 03:27 PM
50 FPS more is about exactly what I would expect the 2.5" extra barrel & cylinder length in front of the chamber on the revolver to give.

If you measure the Model 52 Auto with a cleaning rod down the barrel, it will measure 5" from the breach face.

Do the same with a 6" .357 revolver and it will measure closer to 7 1/2".

rc

LJ-MosinFreak-Buck
November 5, 2011, 08:05 PM
Emile Nagant, the Belgian designer, yes I know. The revolver was used by the Soviets, that's all that counts.

So I guess it makes no difference at all, really.

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