Author Topic: Excessive CB Gap, need professional opinion.  (Read 1115 times)

Offline RUSS123

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Excessive CB Gap, need professional opinion.
« on: January 12, 2020, 04:35:47 PM »
Hi all, new to this forum and this is my first post.

I'll get right to the point: New Uberti 1872 Open Top, 7.5" .38 Special, purchased from Cimarron.

My initial inspection, I noticed visually that the BC gap looked a bit wide. I had not taken the gun apart yet. The BC gap measured .012" with cylinder pulled to the rear. End shake was hardly perceptible at half cocked.  The wedge had been pounded hard. I had to use a brass punch to remove the wedge.

Pulled the barrel, then, checked the Arbor for frame/barrel "overlap" as per Pettyfogger's instructions. There was some overlap but not much. Then I slid the barrel back onto the Arbor to remeasure the BC Gap at the point where the bottom of the barrel and frame come together, then lightly tapped in the Wedge. I could not press the wedge in by hand to where it exited even a little on the opposite side of the barrel. I just gave it a light tap with a safety hammer to hold it in place to do a second BC Gap measurement. What I did should be equal to an Arbor correctly seated with the barrel, as if corrected with a spacer.

The BC Gap measured .018" and of course end shake increased by .006" which I expected.

The thing is, whoever assembled this gun at the factory severly pounded in the wedge to force the barrel in toward the cylinder to provide a "reasonable?" looking BC Gap with little to no end shake.

What I realize is this: If the Arbor interface were to be corrected with the barrel, the BC Gap is going to be enormous. I can't figure any other way to correct the BC Gap spacing error without literally milling about .012" off the bottom of the barrel to frame fit at the two pegs. The front Cylinder bushing would also need to be cut back as well.

Is this correctable or a wash?

I have not contacted Cimarron yet about warranty repair. Not sure that I even want to. What if they say: Well, that's in spec and that's what you get with these guns. Not sure I would even trust their repair. I would be more willing to spend the money for a professional to correct it and tune it all up, if it's possible. I don't want the headspace to be sacrificed to tighten a huge BC Gap.

Please tell me what you think. Am I overlooking something? I need to convince Cimarron that I have a valid repair request.

I'll appreciate all responses.
Russ

Pietta Frontier 7.5 357mag
Uberti 1872 OT 7.5 38 Sp.
Ruger Blackhawk Hunter 44mag
Ruger Single Six Hunter 7.5 22mag Conv.
Ruger Vaquero New 5.5 357mag

Offline 45 Dragoon

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Re: Excessive CB Gap, need professional opinion.
« Reply #1 on: January 12, 2020, 07:23:45 PM »
RUSS123,
   The Barrel assy is supposed to contact the frame where the locating pins are (no gap. I'm sure you know that, didn't want you to think I'm being a smart asp). That could be considered the fulcrum or the pivot in the open top design. The fact that the arbor bottoms out in the arbor hole is what determines the barrel/cyl clearance. I say clearance so most folks in the blk powder world will know what I'm talking about. To modern revolver folks it is understood as endshake. It's not truly a "gap" unless there is a bushing  that actually keeps the cyl face and forcing cone from contacting each other. So, if your revolver has a bushing, it will have a bbl/cyl gap. If it just has a gas ring (prevents cyl binding from fouling) it probably should be an endshake situation. Obviously, if neither a bushing or ring are present, it's definitely an endshake situation.  The nice thing about endshake setups is they can be as close as .0015" - .003" because the cylinder and barrel do meet .  .  .  each time the action is cycled!! They're self cleaning!!!

  So, since you have an Uberti, the arbor is in deed short. My own way of correcting the problem is by installing a single spacer of the correct thickness down the arbor hole. I use JB Weld to keep it in place. I leave the spacer a few thousandths thick so I can "fine tune" to the targeted  spec.  by removing material from the end of the arbor (making it even shorter!!!).  Once the desired spec is reached, the wedge can be driven in and your spec will always be there! Make sure you do all the adjusting with the wedge in with full tension.
  You may also want to drill the end of the arbor through to the wedge slot and thread it. You can then install a set screw (face ground flat ) to act as a wedge bearing .  .  .  an adjustable wedge bearing. You'll never need to replace your wedge not to mention, you can customize the wedge "depth" that it goes in to accommodate easier re-holstering. It may not be a problem with your revolver but it can be a problem on some cap guns.

Mike
www.goonsgunworks.com
Follow me on Instagram @goonsgunworks

Offline Coffinmaker

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Re: Excessive CB Gap, need professional opinion.
« Reply #2 on: January 12, 2020, 07:51:48 PM »
DISCLAIMER:  I only made a living as a CAS gunsmith for about 20 years before I retired.  I was also a specialist for the 1871/72 Open Top

It's simple actually.  Barrel to cylinder gap is optimal at .005/.006 and .018 is unacceptable.  The 1871/72 Open Top has a Gas Ring integral to the Cylinder.  You should be able to seat the wedge far enough to engage the retaining screw with a light tap with the butt of a plastic screwdriver.  End Shake at that point (you have a gas ring - end shake is an issue) should be .002 and your Head Space between cartridge head and recoil shield is optimum at .004/.005.  These amounts are achieved with the wedge seated properly and the retaining screw snug.  If the Wedge also puckered the sides of the barrel lug, it needs replaced.

Your gun doesn't meet any of that criteria.  SEND IT BACK.  In fact, SEND IT BACK for REPLACEMENT.
Tell Cimarron the same thing you have explained here.  DO NOT attempt to fix it.  DO NOT allow anyone else to fix it.  They (Cimarron) owe you WARRANTY.  Also, don't shoot it.  You or anyone else taking tools to it WILL VOID the warranty.


Offline RUSS123

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Re: Excessive CB Gap, need professional opinion.
« Reply #3 on: January 12, 2020, 09:50:46 PM »
Thank you both, 45 Dragoon (Mike) and Coffinmaker,

It's a "Gas Ring" I was referring to. Sorry, lack of nomenclature on my part.

I had downloaded all the articles written by Pettiefogger and read them through several times to be able to talk about it with the understand. I'm no stranger to revolvers. I own 5, 3 of which are Ruger SAs and have measured BC Gaps, head space, end shake, lockups, etc. so it's easy to visually know when a gap appears excessive. I at least know what's operationally essential.

This gun, from my mechanical perspective has no solution outside of cutting material from the face of the barrel mounting where the locating pins go in, in order to bring the forcing cone close enough to the cylinder which would also require to cutting back on the Gas Ring of the cylinder. That would be ridiculous of course but if it were the only open top in the world and your only option, it could be done and all could be good. I don't know if what I'm concluding was every done.

For my own interest, I would love to know what went wrong.

I have not shot it yet.  You both have convinced me that I have a viable warrant replacement request. I will be in contact with Cimarron tomorrow.

By the way Mike.... did you not see my request for service on you web sight. I'm still interested in what you can do for a full tuning service once I get back a gun that's tune-able, so to speak. I also want to have a Ruger style hand spring installed.

It's a shame really! The action on this gun was already quite smooth.

Thanks again...
Russ

Pietta Frontier 7.5 357mag
Uberti 1872 OT 7.5 38 Sp.
Ruger Blackhawk Hunter 44mag
Ruger Single Six Hunter 7.5 22mag Conv.
Ruger Vaquero New 5.5 357mag

Offline 45 Dragoon

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Re: Excessive CB Gap, need professional opinion.
« Reply #4 on: January 12, 2020, 10:21:48 PM »
Hey Russ,

   I did see your email late last night. Sorry I didn't call you. It's been the most unexpected week ever! Last Sunday my wife and her brother took their dad to visit an assisted living facility they had located 2days before. Long story short, we moved him in yesterday!!  So, it was all hands on deck getting his furniture, clothes, new bed stuff, bathroom stuff, T.V. (of course!!) pictures hung from Thurs-Sat. morn. .  Needless to say he was very familiar with his new place!!
  I'm just glad my wife doesn't have to worry about her dad on a daily basis .  .  .  very stressful .  .  .  for 3 yrs!!
  We are both looking forward to a more normal "life" so.

I'll pm ya. Thanks again and thanks to C.M. for your "headspace" info. forgot the dummy cartridge thing!!

Mike
www.goonsgunworks.com
Follow me on Instagram @goonsgunworks

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Re: Excessive CB Gap, need professional opinion.
« Reply #5 on: Today at 03:43:03 PM »

Offline RUSS123

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Re: Excessive CB Gap, need professional opinion.
« Reply #5 on: January 13, 2020, 12:32:21 AM »
Hey Russ,

   I did see your email late last night. Sorry I didn't call you. It's been the most unexpected week ever! Last Sunday my wife and her brother took their dad to visit an assisted living facility they had located 2days before. Long story short, we moved him in yesterday!!  So, it was all hands on deck getting his furniture, clothes, new bed stuff, bathroom stuff, T.V. (of course!!) pictures hung from Thurs-Sat. morn. .  Needless to say he was very familiar with his new place!!
  I'm just glad my wife doesn't have to worry about her dad on a daily basis .  .  .  very stressful .  .  .  for 3 yrs!!
  We are both looking forward to a more normal "life" so.

I'll pm ya. Thanks again and thanks to C.M. for your "headspace" info. forgot the dummy cartridge thing!!

Mike

Mike, I know how that is with aging parents. I helped take care of my wife's mother who came to live with us for 9 years. The last 2 years of her life was very stressful on both of us before she died at the age of 92. Fortunately, we had Hospice help in the last month of her life. She died peacefully one Sunday morning. Hospice was a huge help.

Anyway, I did a more precise and careful measurement. I neglected to realize the affect the bolt can have on measurements and it's why you put your gun at half cocked to have the bolt out of the way. On a Ruger, you just open the gate to bring down the bolt.

So..with wedge pounded in as it was in the box: BC Gap measured:

.012" cylinder forward
.0135" cylinder to the rear
.0015" end shake
.004" head space

Wedge reasonably set with just a light tap of the hammer: BTW, the wedge wouldn't even go in far enough to lock it in with the wedge screw.

.015" cylinder forward
.024" cylinder to the rear "(hard to believe but true)"
.009" end shake

Before asking anyone's opinion about these findings, I was considering to just send it to you for a tuning job anyway, assuming you would fix the spacing as well. Doesn't sound like it's possible with such errors now. Is it?

I'm not in a rush. This, like many other adventures in firearm troubleshooting, design and education, has been a real pleasure.

At this point: When I talk to Cimarron tomorrow and if they agree, they will issue me an RA number to ship for warranty repair.
Russ

Pietta Frontier 7.5 357mag
Uberti 1872 OT 7.5 38 Sp.
Ruger Blackhawk Hunter 44mag
Ruger Single Six Hunter 7.5 22mag Conv.
Ruger Vaquero New 5.5 357mag

Offline RUSS123

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Re: Excessive CB Gap, need professional opinion.
« Reply #6 on: February 09, 2020, 11:57:16 AM »
After talking with Mike in great length, I decided to send it to him instead of seaking warranty. I would be sending it to him anyway for his full blown tune up service. It's in his good hands now and I feel a whole lot better that it is.
Russ

Pietta Frontier 7.5 357mag
Uberti 1872 OT 7.5 38 Sp.
Ruger Blackhawk Hunter 44mag
Ruger Single Six Hunter 7.5 22mag Conv.
Ruger Vaquero New 5.5 357mag

Offline greyhawk

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Re: Excessive CB Gap, need professional opinion.
« Reply #7 on: February 09, 2020, 11:10:16 PM »
Hoping someone might help me get educated here

I get barrel - cylinder gap
I get headspace

Why is end shake referred to separately ?

With the hand on the cylinder ratchet, and hammer down on a nipple (or fired case) - the cylinder will tend to move forward - closing some of the visible barrel to cylinder gap - soon as the chain of fire commences, the cylinder reacts rearward against the recoil shield and it all becomes one?   
What did I miss here??

only got a couple capgunz and a little ruger single six ................................

Offline 45 Dragoon

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Re: Excessive CB Gap, need professional opinion.
« Reply #8 on: February 10, 2020, 08:17:59 AM »
Greyhawk, a barrel/cylinder "gap" is a defined opening that most revolvers have. Since the Colt pattern (open top) allows the cylinder to contact the barrel (each time it's cycled), it doesn't have a "gap" it has a "clearance" or endshake. Endshake is  overall forward/backwards  movement of the cylinder.
  When folks talk about the bbl/cyl clearance in their Colt pattern O.T.'s , many times they call it a "gap" when they actually mean a clearance or endshake. That may be what causes confusion among most of the "blackpowder crowd" as far as semantics is concerned.
  So, your revolver may begin the firing sequence with a ".00" clearance but as you say, the cylinder will move rearward against the recoil ring which will allow the clearance to open fully. For this reason, I believe a smaller "clearance"  (measured with cyl pulled fully rearward)  allows a more efficient burn, less ability for the cylinder to do damage and a much cleaner revolver at the end of the day.

Mike
www.goonsgunworks.com
Follow me on Instagram @goonsgunworks

Offline RUSS123

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Re: Excessive CB Gap, need professional opinion.
« Reply #9 on: February 10, 2020, 04:51:12 PM »
I've read that end shake on a regular revolver (not an open top) is figured by subtracting the measured gap when the cylinder is tightly held forward from the measured gap when the cylinder is held to the rear.... "while the bolt is down".

Example: If you measure a .003" gap with cylinder forward and you then measure .007" when the cylinder is held to the rear... your end shake is: .007"-.003" or .004" of end shake.

What I'm still a little uncertain about is: What then is the Cylinder/Barrel Gap? Would that be the gap by which is measured when the bolt is locked in and holding the cylinder at a certain position?
Russ

Pietta Frontier 7.5 357mag
Uberti 1872 OT 7.5 38 Sp.
Ruger Blackhawk Hunter 44mag
Ruger Single Six Hunter 7.5 22mag Conv.
Ruger Vaquero New 5.5 357mag

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Re: Excessive CB Gap, need professional opinion.
« Reply #10 on: Today at 03:43:03 PM »

Offline 45 Dragoon

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Re: Excessive CB Gap, need professional opinion.
« Reply #10 on: February 10, 2020, 05:41:01 PM »
Actually, bolt lockup has nothing to do with it except for the "operators" ability to move the cylinder forward or backward.
   Russ, you are correct. Total endshake = rear measurement - forward measurement.

  With an Open Top of Colt's design (no cyl bushing), it's nothing but endshake.

Mike
www.goonsgunworks.com
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Offline RUSS123

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Re: Excessive CB Gap, need professional opinion.
« Reply #11 on: February 10, 2020, 09:24:46 PM »
Actually, bolt lockup has nothing to do with it except for the "operators" ability to move the cylinder forward or backward.
   Russ, you are correct. Total endshake = rear measurement - forward measurement.

  With an Open Top of Colt's design (no cyl bushing), it's nothing but endshake.

Mike

Edit: Mike, don't confuse what I've stated below with Open Tops or your reply. Hope you didn't read it yet. I'm just rambling to see what some may say.

Then... it sounds like there is no such thing as C to B gap by itself or by one particular measurement because the gap is variable, depending on how much "play" or end shake exists within the allotted space. It is simple and reasonable to understand that a cylinder has to have some wiggle room or it could bind up from heat expansion for one.

I also understand that you can have a "HUGE GAP" and near ZERO END SHAKE, my Open Top is a good example of that.

When I began learning about revolvers, I've heard some say to check and measure your CB gap and end shake (TWO THINGS?). First, they would give their opinion on what they believe the ideal gap should be so you have some point of reference. As expressed... they would say:  "anywhere between .004" and .008" but no wider" as I recall.  Of course, others may have a different opinions but the point is.... they make GAP sound like a "separate measurement" and any gap between 004" and 008" is good to go and you've got a good gun.

Perhaps, what they are actually expressing is the ideal end shake measurement without giving any clarification about it but that's just a guess on my part but then,.... they would go on to explain how to measure end shake....

And there lays the origin of my confusion.

As realized, you can't have one specific measurement for BC Gap UNLESS... it is solely based on the "MAXIMUM" "cylinder to the rear" and if THAT COULD BE TRUE, it would make for an expressed measurement unstandably clear. It would also be clear if it were based on the "MINIMUM" but no body has said that yet.
Russ

Pietta Frontier 7.5 357mag
Uberti 1872 OT 7.5 38 Sp.
Ruger Blackhawk Hunter 44mag
Ruger Single Six Hunter 7.5 22mag Conv.
Ruger Vaquero New 5.5 357mag

Offline greyhawk

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Re: Excessive CB Gap, need professional opinion.
« Reply #12 on: February 10, 2020, 11:51:52 PM »
Greyhawk, a barrel/cylinder "gap" is a defined opening that most revolvers have. Since the Colt pattern (open top) allows the cylinder to contact the barrel (each time it's cycled), it doesn't have a "gap" it has a "clearance" or endshake. Endshake is  overall forward/backwards  movement of the cylinder.
  When folks talk about the bbl/cyl clearance in their Colt pattern O.T.'s , many times they call it a "gap" when they actually mean a clearance or endshake. That may be what causes confusion among most of the "blackpowder crowd" as far as semantics is concerned.
  So, your revolver may begin the firing sequence with a ".00" clearance but as you say, the cylinder will move rearward against the recoil ring which will allow the clearance to open fully. For this reason, I believe a smaller "clearance"  (measured with cyl pulled fully rearward)  allows a more efficient burn, less ability for the cylinder to do damage and a much cleaner revolver at the end of the day.

Mike

Ok Mike gets the prize (best explanation) 

I haul the cylinder rearward (on my capguns) against the recoil shield and measure the GAP between barrel and cylinder - I am really measuring end shake? but it dont matter because they are both the same thing ?

No ? its end shake on a capgun but the ruger SS has both ? cylinder gap is controlled by the pin bushing against the frame - I had to go look to get this (sometimes go look is a good plan) ..............soo we really dont want end shake in a cartridge gun ? or only a touch of it plus headspace allowance?

I did find it necessary on a couple of older capguns (a Walker and an 1860 army that run on full house loads - had some impact wear on the recoil ring) to remove some metal from the frame to barrel joint in order to get cylinder clearance back to something decent without cocking the barrel to far upwards - mistake I made was replacing the pins with ones that fit too neatly .

The  Army colt also had stripped the notches under the barrel so the creeping loading lever wouldnt function - that repair was beyond my capabilities at the time so I made up a remington style lever, drilled a pivot pin through and it works fine - most fellers wouldnt spot it from more than ten feet  - project guns are fun!

Offline 45 Dragoon

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Re: Excessive CB Gap, need professional opinion.
« Reply #13 on: February 11, 2020, 02:00:30 AM »
   Yes, most revolvers have both  endshake and a bbl/ cyl gap.  As Russ said, endshake allows the cyl to rotate or it would bind. The bbl /cyl gap is created typically by a bushing (some fixed, some removable) that keeps the cylinder "x" distance from contact with the barrel .  .  .  the "defined opening".
  If the cylinder can contact the barrel (as in our open top revolvers) there is no gap, it's all endshake.
  So, the bbl/cyl " clearance " I speak of in my posts is the same as endshake. I think that those folks that don't know the difference between "gap" and "endshake"  can visualize and understand "clearance"  a little easier. Most of the time "arbor correction" (in our Colt/Colt pattern O.T.'s) is in the discussion and it is mentioned that "arbor length" defines the clearance (or endshake). An arbor that is the correct length will result in the same clearance (endshake) every time the revolver is re-assembled. In my experience, a .0025" - .003" bbl/cyl clearance (endshake) results in a more efficient revolver, a more "mechanically" accurate revolver and a cylinder that is too confined to do damage to the "setup" (especially when shooting max loads).  Note : in a cartridge shooting O.T., the clearance (endshake) can be tightened to .002"

Mike
www.goonsgunworks.com
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Offline Coffinmaker

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Re: Excessive CB Gap, need professional opinion.
« Reply #14 on: February 11, 2020, 09:46:04 AM »
There is some understandable confusion when we talk about "open top" guns.  The "Open Top" as we know it from Colt, has an integral gas ring or "bushing" on the cylinder that establishes "End Shake."  End Shake on the "Open Top" is established by the afore mentioned gas ring/bushing.  Head Space on a cartridge revolver is initially established by the Star or Ratchet (same things) which spaces the cylinder away from the recoil shield to allow .004 - .006 between the cartridge head and recoil shield with the bushing holding the end shake at no more than .001 or .002.  This keeps the cartridge head and primer close enough for the firing pin to strike the primer.  This is true for ALL cartridge guns.  Allowing the head space and end shake to open up further is bad juju.  AFTER end shake and head space is correct, we address Barrel to Cylinder gap.  Should be about .004 (Optimum).

When we discuss Percussion Guns, forget all of the above.  Apples and Walnuts now.  With percussion guns, there is no gas ring nor bushing to limit fore and aft cylinder movement.  The limiting factor is the breach end of the barrel.  There is no "Head Space" because there is no cartridge HEAD to space.  The important dimension is the Barrel to Cylinder gap, which establishes the distance between the Hammer Face and the Nipple.  The barrel to Cylinder Gap should be around .006 (Mike and I disagree). The hand will push the cylinder forward until it contacts the breach face of the barrel.  At this point, the hammer face should be just contacting the nipple.  So the definition of the cylinder movement is all "End Shake" but don't confuse yourself.  Just think of it as Barrel to Cylinder gap.

If you work on these guns for a living, it all makes sense.  If you are just looking at the one or two you own, it will be confusing.  If you think about it too much, you'll get a headache.  I recommend Aleve.

FORGOT:  If the assembly puke it Uberti just pounded everything together and screwed with the Gas Ring to make it all "fit" you may well be screwed.  Good Luck.  Two more Aleve.   

Offline 45 Dragoon

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Re: Excessive CB Gap, need professional opinion.
« Reply #15 on: February 11, 2020, 10:32:10 AM »
Thanks CM!  Lol (sometimes it takes 3!)

Mike ;)
www.goonsgunworks.com
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Offline greyhawk

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Re: Excessive CB Gap, need professional opinion.
« Reply #16 on: February 11, 2020, 10:40:19 AM »
I got it fellers ....thanks!
Gettin off my backside and unlocking the safe so I could  LOOK at one of each (capgun and cartridge gun) made the gettin easier (picture is worth a thousand words and all that stuff!)
Problem is I only had one prize and already gave it to Mike so - Coffinmaker - I am real sorry but you gonna have to sneak a sip of his beer while he not lookin .

Jokes aside - I have managed to fiddle three vintage capguns into pretty good shootin shape with the info gleaned from these pages  (Pettifogger then Mike and Coffinmaker) so a thanks to them but more goes to the fellers behind the scenes that keep this site running .
 

Offline 45 Dragoon

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Re: Excessive CB Gap, need professional opinion.
« Reply #17 on: February 11, 2020, 01:48:51 PM »
 ::).       Ooooooops !!! Ah .  .  .  what beer?!  (That beer is GONE!!!! LOL). But thanks Greyhawk (I'll get one for CM!) Congrats for getting some use outta some of my ramblings!!  Always like to help folks if I can .  .  . 

Mike
www.goonsgunworks.com
Follow me on Instagram @goonsgunworks

Offline RUSS123

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Re: Excessive CB Gap, need professional opinion.
« Reply #18 on: February 11, 2020, 03:51:32 PM »
Great write up Coffenmaker. I understood everything.

I think the other confusion if not the main confusion is that Open Tops are both Percussion and cartridge, ie, conversions and my made for cartridge 1972 open top.

Perhaps, Percussions are not considered Open Tops??? If that is true then my statement above is from my lack of knowledge.

I was not confused in what you wrote by the way. You made it very clear about Percussion guns however, my 1872 OT has a Gas Ring which is currently acting as a bushing and maintaining end shake. It is "thin" and according to Mike it should not act as a bushing to control end shake because "it's so thin".  Mike said.... please correct me if I'm wrong Mike... "that the barrel should control the end shake just as you explained for a Percussion gun, with a .003 Barrel to Cylinder gap "Mikes opinion". That will take care of the Headspace. Mike intends to correct it as such and the gas ring will act as a gas ring only and not as a bushing to control the end shake as it does now.

So, what I'm saying: In my case, my "1872 cartridge OT" will be converted or corrected to a Percussion setup when Mike gets done with it, I assume, as it should have been done in the first place by Uberti.

So you know I know: I understand headspace for rimmed cartridge revolvers. It has to be maintained one way or the other. .060" to .074" I think is the SAMMI spec for 375/38 special cartridges, measured from the breech face to cylinder unless there's a recess for the cartridge and in that case, the recess depth is factored in. .014" is the Maximum tolerance. That's quite a lot of wiggle room for end shake actually unless your headspace is edgidging toward the maximum. Headspace is measured with the cylinder held "forward".

I know nothing about Percussion Cap and Ball if there's any kind of similar requirement.

Likewise, I do not know about the Conversion Open Tops, if they are converted so that headspace is controlled by a cylinder bushing versus the face of the forcing cone at the end of the barrel.

What I did learn from you but before you, my discussions with Mike, is the fact of the barrel face being used to control end shake versus a cylinder bushing. What I'm not sure of is why one would be more advantageous over the other however, I can see that using the barrel to maintain end shake, also controls both the gap and headspace all at the same time, assuming a well fitted arbor.

I believe it said in my owner's manual that if the cylinder is binding when putting it back together, to back-off on the wedge a bit. On mine as is, it will only bind on the gas ring leaving a large gap remaining between the cylinder and barrel.   

Please forgive me if you're needing more Aleve. This is all so fascinating to me because I'm new to this stuff and love discussing it. I prefer Aspirin!
Russ

Pietta Frontier 7.5 357mag
Uberti 1872 OT 7.5 38 Sp.
Ruger Blackhawk Hunter 44mag
Ruger Single Six Hunter 7.5 22mag Conv.
Ruger Vaquero New 5.5 357mag

Offline 45 Dragoon

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Re: Excessive CB Gap, need professional opinion.
« Reply #19 on: February 11, 2020, 04:13:52 PM »
That's great Russ!
  The Open Top is the design of the percussion revolvers Colt made. The top strap design is what the Root revolver was as well as the 73 Peace Maker and all the other Colt revolvers made since.
  The '71 Open Top is Colt's first cartridge offering. So it's the " '71"  part that designates that particular open top  as the cartridge one. All the others were percussion revolvers.

Mike
www.goonsgunworks.com
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