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Setting gap & spitting
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mister callan
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July 2, 2011 - 2:44 pm
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Quick background. I have a Monson 15-2 & only 1 BBL ( a vent rib HB in 6") so I don't remove it much. I set the gap with the factory gauge & checked it after tightening the nut. When I went to the range it spit something that was hitting my left cheek. It did not do this previously.

Reading up on this I discovered 2 things. First the spitting is dependent on bullet weight or type! 158 Gr SWC didn't spit, 125 gr HP did!

Second very slightly reducing the gap cured the problem completely, no spitting with either load.

 So how tight should you set the "feel" for the gauge? Should it be just touching, firmly contacting, but slidable, or tight but you can remove & re-insert the gauge?

How much leeway does the gauge have from first contact to quite a lot of hand pressure 1 thou, 2 thou 1/2 a thou??mad

Matthew Quigley on handguns:

“I said I never had much use for one. Never said

I didn't know how to use it.”

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Dave_Ks
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July 2, 2011 - 5:08 pm
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If it cured and the Dan didn't lock up after serveral rounds I say you are good!  The  357max sets at .002 so we have some leeway here.  I will shortly be corrected if I am mistaken.   I think the Standard is .006 so if you had to go .005 or .004 or some where inbetween it would work ok!  I check all Rotate as I set gap and a tight fit though movable is the way I do it. 

DSCN1339.jpg

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Charger Fan
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July 2, 2011 - 10:34 pm
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mister callan said:

 So how tight should you set the "feel" for the gauge? Should it be just touching, firmly contacting, but slidable, or tight but you can remove & re-insert the gauge?

How much leeway does the gauge have from first contact to quite a lot of hand pressure 1 thou, 2 thou 1/2 a thou??mad

I assume that you're going for the standard 15-2 .006" gap.

IMHO, the feeler gauge should slide with a "noticeable, but not too to great" drag as you slide it out & re-insert it. If it's a fairly hard reinsertion, there's a good chance that the "BB" at the rear of the frame is sinking in, letting you slide by with a little margin for error.

As DWA stated, a 15-2 can be set with a tighter b/c gap. I have found that my small frame DW's handle great with a .004 ~ .003" gap & that's what I set 'em at.wink When you're setting your gap, make sure you rotate the cylinder on a Monson/Palmer gun so you are reading your gap from the tightest cylinder hole. Norwich guns are made with tighter tolerances, or so I hear.laugh I don't own one yet. 

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Blacktop
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July 3, 2011 - 1:23 am
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I've shot over a dozen different types of ammo, all factory, through my

15 over the last couple years with no spitting. Yet a couple of months

ago I shot some old Remington wad cutters bro-in-law gave me and

they spit all over the place. screwy

 

-Blacktop

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mister callan
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July 3, 2011 - 9:26 am
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I'm currently using the factory tool, so I'm setting a "Tight", " Medium", or "Loose" 6 thou, but have a set of feeler gauges. I guess the point is that I'm trying to get a best case working setup here & so I can tighten the gap some as long as there are no other problems caused by doing so.

The spitting or not spitting problem seems to be related to very small changes in the gap so I was looking for any input on the differences & the possibility of making prudent changes to eliminate the issue. I was also curious as to how much of a change in gap the variation was creating to try & nail down a spit/no spit range.

Matthew Quigley on handguns:

“I said I never had much use for one. Never said

I didn't know how to use it.”

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zoommb
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July 3, 2011 - 4:33 pm
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Everyone seems to be giving you conservative answers, so let me be the radical here.  I set all of my Dan's to .002 at the tightest position.  No ifs, ands, buts or maybes and no spitting (and no 125 gr. bullets).  If you get spitting at .002 you probably have a timing issue.

Hope this helps.

smile

-Mike

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mister callan
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July 3, 2011 - 7:30 pm
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I don't think its a timing problem as it can be made to appear & disappear with the gap change.

Why no 125 Gr bullets?

Matthew Quigley on handguns:

“I said I never had much use for one. Never said

I didn't know how to use it.”

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Dave_Ks
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mister callan
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July 4, 2011 - 10:37 am
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I found this doing a quick internet search on the subject.

3 posts from a thread on another forum to give you a feel for the info & a link if you really want to get to the nitty-gritty detail. Sounds like a dredge up of an old problem with the K-Frame S&W only??

===========================

The problem with 125 gr. .357 magnums was in the K-frame SW .357s like the Model 19. The real problem was that the forcing cone in these guns was already "thinned" at the bottom. The theory is that the lighter 125 gr. bullets exited the cylinder so fast that more hot plasma, unburned powder, etc. hit the forcing cone and weakened it over time, causing it to crack. This was usually after extensive shooting of lighter bullets. The K-frame magnums were originally designed with the 158 gr. bullet in mind. While flame cutting did occur, I've never heard of a K-frame magnum becoming inoperable due to flame cutting. This is more of a sign of how much a gun has been shot. The gun above has some "normal" flame cutting but it can't be seen because of the lighting.

The L-frames were developed to replace the K-frame partially because of the forcing cone issue but also because shooting a lot of magnum loads could cause excessive end shake. The L-frames have a re-designed forcing cone. The J-frames also have a re-designed forcing cone, which does not protrude as much, presumably protecting it better. There is no problem with shooting 125 gr. loads out of them (of course shooting a lot of rounds through any gun will cause wear).

 

The 125s shot in moderation will harm no firearm more than the other.

Here’s the cause of excessive wear in any revolver shooting a "steady" diet of 125 gr. bullets of any type not just Remingtons. Look at the difference of the lengths of the ogives (noses) out to where the shoulders reach full caliber dia. Now compare it to a 158 gr. bullet. The base of the 125 gr. bullet is at the cyl. gap or just encountering the forcing cone at PEAK pressures thus submitting the areas of concern to more than usual hi pressurized carbon laden, heated pressure . Since the short bullet gives more room for more powder!!!! & From the time the hammer breaks the sear it all takes what 35 milliseconds??? or so to happen ???

This is how it was explained to me as best I can remember!

 

The 125-grain bullets driven to maximum velocities used large charges of relatively slow-burning powders. Hand loaders know the powder types as WW296 and H-110, among others. The combination of slow ball-type powders and the short bearing surface of the 125 bullets allows prolonged gas cutting of the forcing cone and top strap area, accelerating erosion and wear.

Bore scope studies of rifle, machine gun, and auto cannon chamber throats shows a lizard-skin-like texture due to this gas cutting damage, called "brinelling". The results of brinelling are fine micro cracks that weaken the surface of the steel, and further promote erosion. In machine guns and auto cannons, barrel life is measured in terms of "useable accuracy", and round counts that determine this are based on group sizes at engagement ranges.

In the K-frame magnums, the forcing cone dimensions combined with the barrel shank dimensions results in a relatively thin shank at the 6 o'clock position, where a machine cut is made to clear the crane. This is usually where the forcing cone cracks. The L and N frames use much beefier barrel shanks and do not have this cut. S&W intended the K frame magnums to be "carried much and fired seldom" service arms, designed to fire .38 Specials indefinitely, with light to moderate use of .357 Magnums. You notice that S&W has discontinued production of K frame .357 magnums, no doubt due to product liability issues and a couple generations of K frame magnum experience.

 

Lots more discussion here:

http://thefiringline.com/forums/showthread.php?t=455649

 

Matthew Quigley on handguns:

“I said I never had much use for one. Never said

I didn't know how to use it.”

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Pinetor
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July 5, 2011 - 8:57 am
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The worst spitting DW I had was a 22, closing up the gap really helped. As for .357/38, I really have not had much of a spitting issue on any of the 4 I own. I made a little youtube video of what I do ( rightly or wrongly) but its worked for me since 1982.

Generally I can place the feeler guage and screw in the barrel until there is a slight drag. If I can flip the gun so the guage is pointng down and it does not fall out, then its not too loose. But I want to be able to pull it out and re-insert with no trouble (not too tight).

Contrary to others here I have never been able to identify a less than flat face on my main shooter, so I dont often check each cylinder.  I often tend to shoot 125 + rounds per outing. Too close of a gap causes drag due to carbon build up on the face of the cylinder ( and gums up the support it rides on). A 30 second cleaning gets me back in action. But during competition it can be a hassle, so I just don't set it that close.  

While you may be able to minimize spitting via gap setting, I would really consider having the timing checked on a 15-2 if it is constant issue.   

Soap Box, Ballot Box, Ammo Box

in that order.

4 Monson Model 15's

1 Palmer FB 15

1 Rossi 357 Model 92 (lever)

1 CZ 75B

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mister callan
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July 7, 2011 - 4:55 pm
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I got inspired, so I unearthed the standard feeler gauge set I knew I owned (somewhere) & checked all 6 chambers. Then I re-gapped the barrel for 4 thou at the tightest, which incidentally came out to 6 thou at the loosest.

We'll see when I get to the range this weekend. shooting

I'm hoping I set the tightest to 6 thou last time & so had a possible 8 thou on some chambers. I also made a (tiny hidden) mark so I'll know which chamber to use from now on to set the gap.

Matthew Quigley on handguns:

“I said I never had much use for one. Never said

I didn't know how to use it.”

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hemiram
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July 14, 2011 - 8:21 am
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My 715 is just about perfectly even in all positions, about .001 off on one side, so I just make the gap med tight with the cylinder on the "looser" side, and end up with .005-.006 all around. It barely changes when it's hot.

My 15-2 isn't quite as good, if I make the loose side .006, the tight side is .003-.004, and when it's hot, it tightens up to the point when the front of the cylinder is carbon fouled, it doesn't bind, but it drags slightly on the tight side. When I mean hot, I mean you can't touch it, period.

Neither of them have ever spit at all.

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Sweeney
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July 17, 2011 - 10:27 am
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If you're using the factory feeler gauge be sure that there isn't a burr on the edge.  The 0.006" factory gauge I have would actually gap at 0.008" due to a burr from the stamping process.

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Blacktop
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July 17, 2011 - 11:47 am
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You stated in your first post that the 158 grn bullets did not spit but the

125 grn ones did, maybe the 125's are larger an are shaving.

 

If it persisted after gap adjustment I would find a different 125grn

or just not shoot that bullet or another idea would be to buy a barrel

from EWK for $39.99 and try it. They are in stock for the 6"

http://www.ewkarms.com

 

 

-Blacktop

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mister callan
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July 17, 2011 - 3:17 pm
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Possibly the 158 Gr lead semi-wadcutters behave differently from the 125 Gr JHPs so that was a contributing factor? The SWC's & the JHPs measured  .356" but length & material obviously are very different as is the propellant used & its volume. The SWC used bullseye & the JHP H 110.

 

Either way re-setting the gap solved the problem with both!range-time

Matthew Quigley on handguns:

“I said I never had much use for one. Never said

I didn't know how to use it.”

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