Cylinder Reaming

[PaulF70]

I measured the chambers and barrel of my Pietta 1858:

- Chambers: .357-.358
- Bore: .346

If I understand correctly, I do NOT want to ream the chambers, as they are already larger than the bore - correct?

 

[Bad Karma]

You should be fine. But I have to say, that’s the tightest 36 I have heard of.

 

[PaulF70]

That's the lands. Of course. I used one of those screw-to-expand bore measures that you then put in a calipers.

Did it twice, got the same figure.

I have another of these guns, will do that one too.

 

[M. De Land]

I measured the chambers and barrel of my Pietta 1858:

- Chambers: .357-.358
- Bore: .346

If I understand correctly, I do NOT want to ream the chambers, as they are already larger than the bore - correct?

What you need is the barrel groove diameter. The chamber mouths should be at and no more than .001 over generally. Groove diameter is determined by slugging the barrels bore and measuring the slug lands. The bore slug will be the inverse of the barrel lands and grooves. If odd numbered rifling then a tri-mic or Powelly gauge will be needed to get it accurate.
Generally the grooves on these will be .005-.006 deep per side so you most likely are good with the current chamber mouth diameter.

 

[PaulF70]

Can anyone chime in on how often the Piette chambers are right-sized, needing no reaming?

I see that slugging isn't all that cumbersome and will probably do it but am curious if this is really likely to be worth the effort.

 

[Bad Karma]

Can anyone chime in on how often the Piette chambers are right-sized, needing no reaming?

I see that slugging isn't all that cumbersome and will probably do it but am curious if this is really likely to be worth the effort.

The only real experience I have had with Pietta has been with the Shooters Models and they were all appropriately set up. The one standard 1860 Pietta I’ve owned had .449 chambers and .452 bore and didn’t shoot very well. I’m told that’s pretty common for the chambers to run .446-449.

 

[M. De Land]

Can anyone chime in on how often the Piette chambers are right-sized, needing no reaming?

I see that slugging isn't all that cumbersome and will probably do it but am curious if this is really likely to be worth the effort.

It's been my experience that most of the reproductions I've checked have small chamber diameters in relation to groove diameter.

 

[Bad Karma]

I measured the chambers and barrel of my Pietta 1858:

- Chambers: .357-.358
- Bore: .346

If I understand correctly, I do NOT want to ream the chambers, as they are already larger than the bore - correct?

The more I look at this the more I’m convinced there’s something hinky with that pistol. The barrel is correct for a .38/.357 and so are the chambers. They are not correct for a .36 cap and ball pistol. I would suspect that ramming a .380 ball into a .358” chamber is going to be challenging.

 

[LRB]

A well matched chamber will cut a lead ring from the ball when loaded. It will be .001 to .002 over sized to the groove depth after seating.

 

[PaulF70]

The more I look at this the more I’m convinced there’s something hinky with that pistol. The barrel is correct for a .38/.357 and so are the chambers. They are not correct for a .36 cap and ball pistol. I would suspect that ramming a .380 ball into a .358” chamber is going to be challenging.

It shaves a nice ring. .375 balls do NOT shave - but fit tightly.

Maybe I'd better measure one more time. It does sound small.

 

[Bad Karma]

If it turns out the first measurements were correct, you have an ideal candidate for a .38 special conversion! ;-)

 

[Bad Karma]

A well matched chamber will cut a lead ring from the ball when loaded. It will be .001 to .002 over sized to the groove depth after seating.

IF, the chambers are a thousandth or two over the groove diameter. That’s a big IF… only a few Italian replicas are correctly setup in that regard and if it’s a Pietta, none except the Shooters Model are.

 

[M. De Land]

A well matched chamber will cut a lead ring from the ball when loaded. It will be .001 to .002 over sized to the groove depth after seating.

Well maybe, If you have a hemisphere cut in the end of the loading ram and the ram is not in good alignment with the chamber it will secure the ball in the hemisphere and cut a lop sided, off center and often incomplete lead ring as it's pressed into the chamber. This is the reason for match work that a cylinder press should be used outside the gun in my opinion . It's just as easy for the loading ram to be out of alignment with the chambers as it is for the barrel and few of them are in real good barrel/chamber alignment. This is the reason for the range rod test in revolvers.
Even the range rod test is not perfect as the bore it must pass through will be smaller in diameter than will the chamber mouths if set up correctly. It does indicate pretty fair alignment though. Only line boring each chamber through the actual guns frame hole will result in perfect alignment and is why the Custom guns and Freedom Arms are so accurate.
I have a friend that goes through revolvers faster than some men do women and he told me some years ago that of the fifty revolvers he has owned from Freedom Arm only three were true minute of angle guns he could reproduce groups consistently with at 100 yards from sand bags on a bench. Consistent Minute of angle five shot groups from a revolver are rare even from custom guns and Freedom Arms but they do exist but it takes a real "Pistollero" to make them !
Dennis is the best bench rest pistol shot I have ever seen !
There is no physical reason I can think of that the same could not be made true of percussion guns set up with the same attention to detail.

 

[LRB]

I have owned a half dozen percussion revolvers. I have never had one seat the ball with a noticable lop sided cut ring. When on half cock the cylinder is not locked in as in a vise and shifts to receive the ball adequately even. Maybe you have dealt with some very low quality products. I know about the Freedom Arms, but we are not discussing Freedom Arms, this is about affordable common C&B revolvers. I can guarantee you original Colts were not produced to FA quality specs but they did very well enough anyway. People of the C&B revolver period were more practical and realistic with their arms. If they needed a hundred yard shot, they used a rifle.

 

[PaulF70]

Egg on my face here. I previously reported these numbers:

- Chambers: .357-.358
- Bore: .346

I had forgotten the critical step of setting 0 on the calipers. Remeasured the chambers, and they all measure .373-.374.

As noted above my bore measurement is not relevant. I have ordered some soft slugging bullets. After they come I'll post that measurement.

 

[Bad Karma]

Egg on my face here. I previously reported these numbers:

- Chambers: .357-.358
- Bore: .346

I had forgotten the critical step of setting 0 on the calipers. Remeasured the chambers, and they all measure .373-.374.

As noted above my bore measurement is not relevant. I have ordered some soft slugging bullets. After they come I'll post that measurement.

Haha! Well, it had us going for a bit!

 

[PaulF70]

 

[Bad Karma]

Do anything for longe enough and you're bound to screw up somewhere… personally, I like to get the screwups out of the way as soon as possible!

 

[bang]

All my Piettas 36 prefer a .380. gives more bearing surface.
.001 will wash out in the forcing cone easily.

 

[PaulF70]

I just noticed something else: This isn't a Pieta Remington 1858 revolver, it's a Glock 43.

No wonder it was hard to get the cylinder out.

Ok, boys, nothin' but serious shootin' from here on out!!