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Author Topic: Why do Italian Repro Revolvers have undersized cylinder chambers?  (Read 7221 times)

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tscmmhk

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I own several different brands (Pietta & Uberti) cap / ball revolvers and all of them have undersized cylinder chambers. For example, the Pietta 1860 Army has cylinder chambers that measure .443" / .442". I have slugged the bore on the 1860 and the groove diameter is .452". I'm certainly OK with the barrel groove diameter at .452" but why are the cylinder chambers almost .010" smaller? There might be a reason but I haven't figured it out yet. I'm guessing it might be a lawyer thing but then i would only be guessing. All of my revolvers have smaller cylinder chambers so it isn't necessarily a Pietta problem because the Uberti revolvers have the same issue. Does anyone know the reason they make C&B revolver this way?

Thanks,

Tom
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swathdiver

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Re: Why do Italian Repro Revolvers have undersized cylinder chambers?
« Reply #1 on: December 23, 2013, 10:11:34 PM »

Probably to cut down the pressure if some yahoo puts too much Triple 7 in it.

I have several .36 caliber revolvers from Pietta and ASM and they all have chambers larger than groove diameter.  Years apart, a Pietta Colt and Remington have .369 chambers and .367 groove diameters.  They are tack drivers!  The ASM has .374 chambers with a .372 groove diameter and it too is very accurate, especially with its faster 1:21 twist.
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StrawHat

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Re: Why do Italian Repro Revolvers have undersized cylinder chambers?
« Reply #2 on: December 28, 2013, 06:56:55 AM »

The undersized chambers predates 777 by a long time.  I recall more than a few competitiors boring the chambers to a larger diameter on original Colts and Remingtons when they were popular on the firing line.  It might be that was the way the originals were built and therefor the way the replica makers built them.
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Hoof Hearted

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Re: Why do Italian Repro Revolvers have undersized cylinder chambers?
« Reply #3 on: January 07, 2014, 07:47:27 AM »

My opinion is that the chambers are bored "tighter" to cause "shaving" of your balls!

This stands to reason in today's litigious society and it reduces the chance of chainfires. If the makers were concerned with accuracy they would do many things differently..............

HH

tscmmhk

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Re: Why do Italian Repro Revolvers have undersized cylinder chambers?
« Reply #4 on: January 10, 2014, 09:34:43 PM »

Based on what I have read and people I have personally talked to, I decided to ream the cylinders on three of my Cap&Ball revolvers to prevent "shaving" my balls. ;) The Pietta 1860 Colt Army, Uberti 1858 Remy and my Pietta 1858 Remy got a cylinder ream job. I did the work myself using a Manson piloted .452" cylinder throat chamber reamer from Brownells. Took about a hour to complete and I must say the Manson tool does a nice job.
The next part is to wait until the weather gets better and go try all three revolvers at the gun range. Hopefully I'll see some improvement in accuracy.
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long hunter

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Re: Why do Italian Repro Revolvers have undersized cylinder chambers?
« Reply #5 on: January 10, 2014, 11:29:16 PM »

You still need that "shaving". That's what prevent chainfires. If your chambers are .452, you need a .454 ball. Chamfering chamber mouths helps too.
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tscmmhk

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Re: Why do Italian Repro Revolvers have undersized cylinder chambers?
« Reply #6 on: January 11, 2014, 07:45:08 AM »

I'll be using .457" lead round balls for sure and yes I chamfered the chamber mouths slightly to help swage the lead ball. That should give me a good seal to prevent a chain fire.
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curator

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Re: Why do Italian Repro Revolvers have undersized cylinder chambers?
« Reply #7 on: January 11, 2014, 11:04:24 AM »

Hoof Hearted has it right. The Italian manufacturers want to be sure litigious Americans won't have chain-fires. They also know most revolver buyers will not shoot these guns very much and will be satisfied if it goes BOOM and they occasionally hit something. When I was working in the museum business, I miked many, many original C&B revolvers' chambers and bores. I rarely encountered one that had chambers smaller than bore size. The one I did find had a miss-matched cylinder based on serial numbers, and that on a Manhattan Navy, was only about .002" under. Italian replica C&B revolvers' chambers vary from .002" over (special "shooter models') to about .006 under. Nothing compares with My ASM Walker that had .446" chambers and .468 groove barrel. Balls pushed out of the chambers would free-fall down the barrel.
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Frank Graves

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Re: Why do Italian Repro Revolvers have undersized cylinder chambers?
« Reply #8 on: January 11, 2014, 05:57:47 PM »

At The Gathering of Patersons at the 2008 meeting of the Texas Gun Collectors Association, I measured the chambers of the cylinder and the corresponding barrels of the original #2 and #3 Belt Model Colt Paterson revolvers there as there was a similar rumor about the Colt Paterson revolvers.  Without exception, each cylinder's chambers measured about .0125" to .0150" LESS than its matching barrel, land to groove.  Either Sam Colt thought the bullet would expand upon the powder charge igniting as it entered the barrel, or was fearful of too much pressure as is the thinking here about the replicas.  It was such an early time for the repeating revolver in 1836, either could have easily been Colt's motivation.  Iron was a lot softer and more inconsistent back then.  Interestingly, the caliber for this revolver is listed today at either .31 or .34.  I guess it depends on whether you think the caliber of the gun is the diameter of the ball that you put in the cylinder, or the diameter of the barrel at the muzzle.
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Jaxenro

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Re: Why do Italian Repro Revolvers have undersized cylinder chambers?
« Reply #9 on: January 12, 2014, 04:20:56 AM »

What I never understood is why doesn't some gunsmith specialize in reaming cylinders to the proper size. Seems like it would be a quick fee $$$ every week as someone is always asking
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The Old Man

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Re: Why do Italian Repro Revolvers have undersized cylinder chambers?
« Reply #10 on: January 12, 2014, 04:49:05 PM »

I have a Euroarms 1858 that was made in 1974. It's chambers are .450    The groove dia of the barrel in .450 also. The
chambers are champered.


« Last Edit: January 12, 2014, 05:06:10 PM by The Old Man »
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swathdiver

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Re: Why do Italian Repro Revolvers have undersized cylinder chambers?
« Reply #11 on: January 12, 2014, 10:12:36 PM »

Have recently come across 3 ASMs with chambers way over groove diameter, a Navy 4 thousandths over and a .44 brasser 1860 5-6 thousandths over.  Then there's another 1860 with a .4575 groove diameter barrel with .447 chambers!  LOL

Then there's the ASM Walker with the chambers .001 over and it's a tack driver and tight enough to shoot .451s.
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tscmmhk

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Re: Why do Italian Repro Revolvers have undersized cylinder chambers?
« Reply #12 on: January 13, 2014, 12:27:42 PM »

After all the responses to my original question I have come to the conclusion that Italian repro revolvers are all over the place as far as cylinder dimensions. It also looks like the lawyers have got their sticky fingers in the mix to prevent law suits. ::) I have heard the opinion on other forums that most Italian repro revolvers today are about 90% finished /fitted. With my limited experience with cap&ball revolvers I couldn't agree more. Some of us have become amateur gunsmiths out of necessity but then that's not a bad thing.
One question I do have is there any book(s) or document(s) that captures all these gunsmithing tips dealing with cap & ball revolvers?
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Jaxenro

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Re: Why do Italian Repro Revolvers have undersized cylinder chambers?
« Reply #13 on: January 13, 2014, 12:59:34 PM »

Not that I know of but I have a few pdf's I collected
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The Old Man

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Re: Why do Italian Repro Revolvers have undersized cylinder chambers?
« Reply #14 on: January 13, 2014, 07:24:52 PM »

Well in my 50 years of being in this game, I have had several brands.  I have had all of them
apart doing things like lighter trigger pulls and replacing stuff when it breaks. All of the inside
parts look like stamp metal. Except one. And that is the one I bought about two years ago for
85.00.  I had just finished shooting the "As Issue" matches at the Nationals at Friendship In.
and I was sitting at a picnic table next to the range. I took it completely apart. I used to work in
a tool & die shop for 20 years in quality control so I know what good machining looks like. Well
the hand, trigger, and bolt all looked they were machined . I have never seen anything like it.
Either someone did machine these parts, or it came from the factory like this. What kind is it
your asking. Well it is the Euroarms made in 1974. How did I do you ask. Well I won two 1st place
gold medals. It does shoot and had a very light 1 1/2 lb. target trigger. I don't know if all Euroarms
made in the early 70's are like this or not. Never have seen another one. If any of you have one
let me know. There is a picture of it in the thread up a little. I did the de-fared and the antique
look.
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