Revolver problems with good or bad seal

TXAZ · August 27, 2016, 12:31 PM

I'm not a revolver guy, but was wondering about someone shooting an old revolver that didn't have a good gas seal between the barrel and cylinder.
I'm guessing there's a couple of problems:
1) lower muzzle velocity
2) hot gas escaping might burn your hand

Is that common? How do you stay safe and avoid crispy fingers?

Doyle · August 27, 2016, 12:34 PM

How big is the gap? There needs to be a gap sufficient to allow free turning of the cylinder even with a little carbon buildup. If it has developed what is called "end shake" then you may be able to tighten up that gap yourself. What make and model of revolver?

TXAZ · August 27, 2016, 12:38 PM

Don't know the specific model Doyle. Might have been a S&W.
More curiosity than anything else.
Are there any warning signs before you burn your fingers?

buck460XVR · August 27, 2016, 01:10 PM

How did you know it had a bad "seal"? All revolvers have a gap between the cylinder and the forcing cone for the reason Doyle stated. Hot gases from even the newest and tightest, can burn your hand if you hold the gun wrong...in the case of .460s, the escaping gases can take off your finger. Plenty of pictures to prove it, just GTS. Lower muzzle velocity is also a concern, but again, something you accept when buying a revolver. Again, just the nature of the beast. Some numbers thrown out iffin I remember correctly is one loses about 1.5% of total velocity for each .001" of gap as opposed to a solid test barrel. Excessive cylinder gap can lead to lower velocities, and the spitting of lead and unburnt powder in your face. Some folks say it can contribute to a loss of accuracy...others say it has no effect. Folks like to brag about their revolvers having excessively tight Cylinder gaps, but this can be worse than loose. Only way for most folks to determine if the gap is excessive is to measure. S&W now considers 0.012" barrel-to-cylinder gap to be acceptable. 0.006" is considered optimum. Most folks feel anything between .006 and .008 as excellent. Excessive endshake may be a sign of other problems tho, such as a gun being abused and shot out with high pressure loads. Or it can just be someone shot a ton of ammo thru it. In many cases it is an easy fix.

A good article.....

http://www.ballisticsbytheinch.com/gaptests.html

g.willikers · August 27, 2016, 02:02 PM

The gas seal in firearms is provided by the case of the ammo expanding and sealing up against the chamber walls.
At the front of a revolver, there is no actual gas seal in the usual sense.
Unless you happen to have one of those revolvers designed to be used with a suppressor.
So watch your digits.
Any loss of velocity from the cylinder to barrel gap would mostly only be known from chronograph readings, and probably more from variances in the ammo itself.
Spitting of lead is usually a sign of mis-alignment of cylinder rotation to the barrel due to timing issues.
So if yours is doing that, stop shooting the danged thing.
The folks around you will appreciate it.

TXAZ · August 27, 2016, 02:40 PM

Thanks gentlemen. I don't own a revolver, probably never will, but one next to me on a firing range seemed like you could see a little light between the cylinder and barrel.

Radny97 · August 27, 2016, 02:42 PM

The hot gases hurting your fingers issue is certainly real, but sometimes overstated. Putting your fingers next to or on the gap will surely hurt you. But gripping a revolver forward, with perhaps a finger over the trigger guard and more than an inch away from the gap will not hurt you in any modern handgun at 357 mag velocities or smaller. I would be a little more careful with 44 mag or greater.
I have tinkered quite a bit with cylinder gap and accuracy on a Dan Wesson revolver where the removable barrel lets you adjust the gap. I did not measure velocity changes because I didn't have a chronograph. Not too surprisingly I found that a .006 gap gave the most accurate groups. .004 and .002 were slightly less accurate. .008 was lots less accurate.
I guess the manufacturers know what they are doing when they say a revolver should be set to a .006 gap.

Doyle · August 27, 2016, 03:46 PM

Quote:

Thanks gentlemen. I don't own a revolver, probably never will, but one next to me on a firing range seemed like you could see a little light between the cylinder and barrel.
__________________

Quite normal - especially for a magnum-type caliber.

James K · August 27, 2016, 09:13 PM

There have been revolvers made to seal the barrel-cylinder gap, the most common one being the Russian Nagant, but the "solution" has always been more complicated than it was worth.

There are two ways to fix the "problem". 1) Keep the fingers out of the way of escaping gas, or 2) practice yelling "ouch" when the gas nips your fingers.

Jim

RIDE-RED 350r · August 28, 2016, 05:07 PM

All good answers..

All revolvers will have a "blast ring" that emanates from between the cylinder and forcing cone, it's unavoidable and as stated above, the nature of the beast. The best thing to do is to understand that proper two-handed grip on a revolver is different than what it considered proper for an auto. Do not get into the habit of extending the non firing index finger along the weapon. If you use that firing grip technique on anything 357mag and above, you may be in for a painful reminder.. And as stated above, it's true that the new "super mags" (for lack of a better term to differentiate them from 357, 44, etc) IE 460S&W, 500S&W, and probably 454 Casull and a few others can and have taken or badly mangled digits on shooters' hands who did not use proper grip technique for a revolver. Use the proper grip, and you will be fine. Keep your fingers to the rear of the cylinder gap.

Salmoneye · August 29, 2016, 09:50 AM

Perfectly normal...

https://upload.wikimedia.org/wikiped...from_S%26W.jpg

g.willikers · August 29, 2016, 10:33 AM

^^^
Eghads, Holy Cow, we better trade our revolvers for something safer.

wizrd · August 29, 2016, 11:04 AM

Too little of a gap between the cylinder & forcing cone - and things can heat up enough & expand enough to lock up the cylinder in an extended shooting session. I had two S & W 66's that would do this when they were new. A trip to a reputable S & W smith & armourer could find nothing but he did say the gap was extremelt close, -- not .357 Mag. loads, just regular, not hot, .38 Spec. loads. This corrected itself in time.
As for the escaping gasses being able to do physical damage, there was a world class, competition shooter a while back, that while doing a 'press check' on his semi-auto, 1911 platform, had an unintentional discharge for some reason, he lost the flesh on the distal joint of his trigger finger. (Finger was over the guide rod, right next to the muzzle). This caused him problems in later competitions, as the RO would disqualify him for moving between stations with his finger seemingly, 'on the trigger'. Due to the last joint not being there, it looked like he had his finger on the trigger, an automatic DQ. -- I forget his name, maybe someone here remembers it. Be careful where you put your fingers.

T. O'Heir · August 29, 2016, 12:55 PM

"...gas seal between the barrel and cylinder..." There is no gas seal between the barrel and cylinder on a revolver.
There was a Russian Nagant that had the cylinder move forward and close the cylinder gap, but no other revolvers that I've heard of do that.
"...stay safe and avoid crispy fingers?..." You hold it correctly. And keep your off hand away from the cylinder gap. Your off hand goes underneath and/or in front of your gun hand.
It was the practice of yelling Уч!, not ouch! snicker.

James K · August 29, 2016, 08:46 PM

FWIW, the old Savage-North revolver cylinder moved forward to fit around the end of the barrel, but obviously there was no cartridge case to insert into the barrel itself as in the Russian Nagant.

Jim

jrothWA · August 29, 2016, 09:15 PM

any thing greater or less need to be corrected.

Driftwood Johnson · August 30, 2016, 03:18 PM

Quote:

any thing greater or less need to be corrected.

Within reason.

I don't remember exactly what the barrel/cylinder gap is on this old 44-40 Merwin Hulbert but I seem to recall it is in excess of .012. The gun is well over 100 years old, and I only shoot it with Black Powder. I shoot it one handed, so my other hand is nowhere near the barrel cylinder gap. There is no appreciable loss of velocity because of the wide gap, at least not that I have been able to determine, and it hits everything that I point it at.

SIGSHR · August 31, 2016, 02:07 PM

The Dan Wesson allows you to adjust the B/C gap. A good idea to check the rear of the barrel, make sure it is smooth and flat.

James K · September 1, 2016, 08:16 PM

DW supplies a feeler gauge with its revolvers that have extra barrels. If you have such a DW revolver but have lost the gauge, the company will send one on request. (True an .006" feeler gauge will work, but using the proper gauge makes sure the company procedure is followed.)

Jim

Stargater53 · September 3, 2016, 09:29 PM

The tolerances for barrel/cylinder gap back in the 80s was .004-.009. The optimal for accuracy and velocity was .006 and is what most companies strived for. Many, who wanted top velocity, went to gun shops prepared to measure the gaps of available guns to get the tightest. But then gun magazines entered the fray.

Back then, gun mags actually published relevant technical material from time to time. And many writers were curious as to the effects of B/C gaps on revolver velocities. But the data they published raised more questions than they answered. First, tiny differences in barrel diameter tend to queer the results. Also, barrel twist and other variables interfered. So they turned to Dan Wesson Pistol Pacs to eliminate as many variables as they could. Since DW owners could use the same barrels and frames and choose their own B/C gaps. But even then the differences weren't as pronounced as they expected. But less B/C gap did, in fact, result in higher velocity, but the results weren't as much as many expected. With today's powders and bullet weights, I don't know what kind of results we'd see now, but it would be nice to see some updated articles appearing, but we all know that no one shoots revolvers anymore (as they became obsolete some years ago).

August 27, 2016, 12:31 PM	#1
TXAZ Senior Member Join Date: September 5, 2010 Location: McMurdo Sound Texas Posts: 4,322	Revolver problems with good or bad seal I'm not a revolver guy, but was wondering about someone shooting an old revolver that didn't have a good gas seal between the barrel and cylinder. I'm guessing there's a couple of problems: 1) lower muzzle velocity 2) hot gas escaping might burn your hand Is that common? How do you stay safe and avoid crispy fingers? __________________ Cave illos in guns et backhoes

August 27, 2016, 12:38 PM	#3
TXAZ Senior Member Join Date: September 5, 2010 Location: McMurdo Sound Texas Posts: 4,322	Don't know the specific model Doyle. Might have been a S&W. More curiosity than anything else. Are there any warning signs before you burn your fingers? __________________ Cave illos in guns et backhoes

August 27, 2016, 02:02 PM	#5
g.willikers Senior Member Join Date: September 28, 2008 Posts: 10,442	The gas seal in firearms is provided by the case of the ammo expanding and sealing up against the chamber walls. At the front of a revolver, there is no actual gas seal in the usual sense. Unless you happen to have one of those revolvers designed to be used with a suppressor. So watch your digits. Any loss of velocity from the cylinder to barrel gap would mostly only be known from chronograph readings, and probably more from variances in the ammo itself. Spitting of lead is usually a sign of mis-alignment of cylinder rotation to the barrel due to timing issues. So if yours is doing that, stop shooting the danged thing. The folks around you will appreciate it. __________________ Walt Kelly, alias Pogo, sez: “Don't take life so serious, son, it ain't nohow permanent.”

August 27, 2016, 02:40 PM	#6
TXAZ Senior Member Join Date: September 5, 2010 Location: McMurdo Sound Texas Posts: 4,322	Thanks gentlemen. I don't own a revolver, probably never will, but one next to me on a firing range seemed like you could see a little light between the cylinder and barrel. __________________ Cave illos in guns et backhoes

August 29, 2016, 10:33 AM	#12
g.willikers Senior Member Join Date: September 28, 2008 Posts: 10,442	^^^ Eghads, Holy Cow, we better trade our revolvers for something safer. __________________ Walt Kelly, alias Pogo, sez: “Don't take life so serious, son, it ain't nohow permanent.”

August 27, 2016, 12:34 PM	#2
Doyle Senior Member Join Date: June 20, 2007 Location: Rainbow City, Alabama Posts: 7,167	How big is the gap? There needs to be a gap sufficient to allow free turning of the cylinder even with a little carbon buildup. If it has developed what is called "end shake" then you may be able to tighten up that gap yourself. What make and model of revolver?

August 27, 2016, 01:10 PM	#4
buck460XVR Senior Member Join Date: December 28, 2006 Posts: 4,342	How did you know it had a bad "seal"? All revolvers have a gap between the cylinder and the forcing cone for the reason Doyle stated. Hot gases from even the newest and tightest, can burn your hand if you hold the gun wrong...in the case of .460s, the escaping gases can take off your finger. Plenty of pictures to prove it, just GTS. Lower muzzle velocity is also a concern, but again, something you accept when buying a revolver. Again, just the nature of the beast. Some numbers thrown out iffin I remember correctly is one loses about 1.5% of total velocity for each .001" of gap as opposed to a solid test barrel. Excessive cylinder gap can lead to lower velocities, and the spitting of lead and unburnt powder in your face. Some folks say it can contribute to a loss of accuracy...others say it has no effect. Folks like to brag about their revolvers having excessively tight Cylinder gaps, but this can be worse than loose. Only way for most folks to determine if the gap is excessive is to measure. S&W now considers 0.012" barrel-to-cylinder gap to be acceptable. 0.006" is considered optimum. Most folks feel anything between .006 and .008 as excellent. Excessive endshake may be a sign of other problems tho, such as a gun being abused and shot out with high pressure loads. Or it can just be someone shot a ton of ammo thru it. In many cases it is an easy fix. A good article..... http://www.ballisticsbytheinch.com/gaptests.html

August 27, 2016, 02:42 PM	#7
Radny97 Senior Member Join Date: July 8, 2015 Posts: 1,021	The hot gases hurting your fingers issue is certainly real, but sometimes overstated. Putting your fingers next to or on the gap will surely hurt you. But gripping a revolver forward, with perhaps a finger over the trigger guard and more than an inch away from the gap will not hurt you in any modern handgun at 357 mag velocities or smaller. I would be a little more careful with 44 mag or greater. I have tinkered quite a bit with cylinder gap and accuracy on a Dan Wesson revolver where the removable barrel lets you adjust the gap. I did not measure velocity changes because I didn't have a chronograph. Not too surprisingly I found that a .006 gap gave the most accurate groups. .004 and .002 were slightly less accurate. .008 was lots less accurate. I guess the manufacturers know what they are doing when they say a revolver should be set to a .006 gap.

August 27, 2016, 09:13 PM	#9
James K Member In Memoriam Join Date: March 17, 1999 Posts: 24,383	There have been revolvers made to seal the barrel-cylinder gap, the most common one being the Russian Nagant, but the "solution" has always been more complicated than it was worth. There are two ways to fix the "problem". 1) Keep the fingers out of the way of escaping gas, or 2) practice yelling "ouch" when the gas nips your fingers. Jim

August 28, 2016, 05:07 PM	#10
RIDE-RED 350r Senior Member Join Date: November 2, 2014 Posts: 425	All good answers.. All revolvers will have a "blast ring" that emanates from between the cylinder and forcing cone, it's unavoidable and as stated above, the nature of the beast. The best thing to do is to understand that proper two-handed grip on a revolver is different than what it considered proper for an auto. Do not get into the habit of extending the non firing index finger along the weapon. If you use that firing grip technique on anything 357mag and above, you may be in for a painful reminder.. And as stated above, it's true that the new "super mags" (for lack of a better term to differentiate them from 357, 44, etc) IE 460S&W, 500S&W, and probably 454 Casull and a few others can and have taken or badly mangled digits on shooters' hands who did not use proper grip technique for a revolver. Use the proper grip, and you will be fine. Keep your fingers to the rear of the cylinder gap.

August 29, 2016, 09:50 AM	#11
Salmoneye Senior Member Join Date: December 31, 2011 Location: Vermont Posts: 2,076	Perfectly normal... https://upload.wikimedia.org/wikiped...from_S%26W.jpg

August 29, 2016, 11:04 AM	#13
wizrd Senior Member Join Date: February 26, 2012 Posts: 232	Too little of a gap between the cylinder & forcing cone - and things can heat up enough & expand enough to lock up the cylinder in an extended shooting session. I had two S & W 66's that would do this when they were new. A trip to a reputable S & W smith & armourer could find nothing but he did say the gap was extremelt close, -- not .357 Mag. loads, just regular, not hot, .38 Spec. loads. This corrected itself in time. As for the escaping gasses being able to do physical damage, there was a world class, competition shooter a while back, that while doing a 'press check' on his semi-auto, 1911 platform, had an unintentional discharge for some reason, he lost the flesh on the distal joint of his trigger finger. (Finger was over the guide rod, right next to the muzzle). This caused him problems in later competitions, as the RO would disqualify him for moving between stations with his finger seemingly, 'on the trigger'. Due to the last joint not being there, it looked like he had his finger on the trigger, an automatic DQ. -- I forget his name, maybe someone here remembers it. Be careful where you put your fingers. __________________ Sumo magis ammo

August 29, 2016, 12:55 PM	#14
T. O'Heir Senior Member Join Date: February 13, 2002 Location: Canada Posts: 12,453	"...gas seal between the barrel and cylinder..." There is no gas seal between the barrel and cylinder on a revolver. There was a Russian Nagant that had the cylinder move forward and close the cylinder gap, but no other revolvers that I've heard of do that. "...stay safe and avoid crispy fingers?..." You hold it correctly. And keep your off hand away from the cylinder gap. Your off hand goes underneath and/or in front of your gun hand. It was the practice of yelling Уч!, not ouch! snicker. __________________ Spelling and grammar count!

August 29, 2016, 08:46 PM	#15
James K Member In Memoriam Join Date: March 17, 1999 Posts: 24,383	FWIW, the old Savage-North revolver cylinder moved forward to fit around the end of the barrel, but obviously there was no cartridge case to insert into the barrel itself as in the Russian Nagant. Jim

August 29, 2016, 09:15 PM	#16
jrothWA Senior Member Join Date: November 11, 2006 Posts: 2,519	Normally, the cylinder gap should be .005 - .008" any thing greater or less need to be corrected.

August 31, 2016, 02:07 PM	#18
SIGSHR Senior Member Join Date: September 13, 2005 Posts: 4,700	The Dan Wesson allows you to adjust the B/C gap. A good idea to check the rear of the barrel, make sure it is smooth and flat.

September 1, 2016, 08:16 PM	#19
James K Member In Memoriam Join Date: March 17, 1999 Posts: 24,383	DW supplies a feeler gauge with its revolvers that have extra barrels. If you have such a DW revolver but have lost the gauge, the company will send one on request. (True an .006" feeler gauge will work, but using the proper gauge makes sure the company procedure is followed.) Jim

September 3, 2016, 09:29 PM	#20
Stargater53 Member Join Date: October 17, 2014 Posts: 94	The tolerances for barrel/cylinder gap back in the 80s was .004-.009. The optimal for accuracy and velocity was .006 and is what most companies strived for. Many, who wanted top velocity, went to gun shops prepared to measure the gaps of available guns to get the tightest. But then gun magazines entered the fray. Back then, gun mags actually published relevant technical material from time to time. And many writers were curious as to the effects of B/C gaps on revolver velocities. But the data they published raised more questions than they answered. First, tiny differences in barrel diameter tend to queer the results. Also, barrel twist and other variables interfered. So they turned to Dan Wesson Pistol Pacs to eliminate as many variables as they could. Since DW owners could use the same barrels and frames and choose their own B/C gaps. But even then the differences weren't as pronounced as they expected. But less B/C gap did, in fact, result in higher velocity, but the results weren't as much as many expected. With today's powders and bullet weights, I don't know what kind of results we'd see now, but it would be nice to see some updated articles appearing, but we all know that no one shoots revolvers anymore (as they became obsolete some years ago).

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