Pietta 1860 reaming chambers

[FlyingZebra]

My Pietta 1860 ( date code BD, 1994 ) has one chamber with marginally less volume than it's neighbors.
I've thought of setting it up in the rotary table and equalizing the chambers.

Anyone here gone through this before?
Anyone know of a rental reamer for these stepped chambers?
Anyone here do this with the intent to open up the chambers?
Mine are right about .446 - and not terribly round, the groove diameter is right around .451 and not completely consistent (seven groove...)





Thanks in advance
FZ

[Lefty Dude]

Just buy a new Cylinder. The new Pietta Cylinders are made with better tolerance than the old.
The bolt notches are cut more precision and consistent cut to cut.

[FlyingZebra]

Lefty thanks for the comment.

Do you know how well the new parts work with the older pre-CNC guns?
Since penning the orig message here I've found a surplus 11.5mm (.4528") spiral flute chucking reamer for six bucks.
It'll arrive in a few days, and I'll set up on the mill for a shape-up of these six chambers.
I've been machining since the early 70's so at least my part of the cylinder will be done right.

Hopefully the outta-spec part of the one funny chamber isn't in the smaller bore portion of the hole.
We'll see.



-FZ

[Lefty Dude]

I picked up a used cylinder for my Pietta 51/36 at the National Muzzle Loader Western Shoot Friday, held here in Arizona. A local vender had it on the table for $20.00. I got it for $15.00. I wanted it as an extra for the piece. It is pre-CNC. The bolt notches are narrower than the current product. The cylinder over-all length is the same as the one that came with the 51/36. I tried to fit the existing bolt to the notches by using my de-burring scrapers. The bolt is fit to the existing cylinder, so if I fit the bolt to the old type cylinder it will be very sloppy for the existing. The difference is about .008"-.010". More than I care to hand scrape with my de burring tool.
The notches are the only issue, Arbor and length are correct.

If I were using this for a replacement Cylinder and not a spare I would fit a new bolt for this used Cylinder.
For $15.00, this cylinder will be in the parts drawer, till I find a use or possible trade for what ever.

[FlyingZebra]

Sounds lime a good deal on that cylinder.

I dug through boxes of older supplies - knew for sure I had a spare around here somewhere.
It ended up being a new in the box spare for my .36

I'll report on how this reaming goes.  At least I will be sending proper sized projectiles down the snoot.



-FZ

[Flint]

I opened up the older cylinder notches with a Woodruff key cutter....

[Lefty Dude]

Flint;
Would you like to do mine ?

[rifle]

It is possible to punt when it comes to a cylinder with small notches to be a spare on a gun with original wider notches.
Carefully put a minimal bevel on the sides of the bolts head. Minimal where the bolt still favors the original cylinders notches but...can get in the spare with small notches enough to work with that.

Using a spiral flute chucking reamer has the chance of trying to pull itself into the chamber so....a four flute straight flute chucking reamer works better.

Setting up on an exiting hole isn't like setting up to drill a hole. A lot of machinists drill holes in the right place easy enough but...when it comes to setting up to ream an existing hole some don't have a good process for that.

Shooting balls makes for more user friendly with reamers in case the set up is a coupla .001's off. The forcing cone cn be widdened a bit if need be with balls. A slightly elongated and wide forcing cone can help guide balls to the center of the bore.

Be careful when reaming in regards to depth. The smaller size deep in the chamber is there to protect the thickness of the wall where the notches are.

I like to size the chambers at .003 over groove diameter. Sometimes right at and sometimes .001-.002 over the grooves too. Depends on the gun barrel and my mood that day.

If the barrel has rifling grooves deeper on one side than the other then I'll go to .003 over groove to make sure the balls lead gets to the bottomof the grooves and then.....face off the crown so all the grooves release the gases simaltaneously so the barrel doesn't shoot like a barrel with a bad crown.

Over size balls don't always get to the bottom of the grooves like one might thunk. It depends on the relationship between the diameter of the ball andn the depth of the grooves. Lead can sorta swag backwards and pull itself from getting to the bottom of the grooves. The 36's are good fer that. The 45's are better at letting the lead to the bottom of the grooves. Different relationship between the rifling depth and the diameter of the ball.

Don't believe me? Take an oversize ball and tap it into the rifling of a 36cal. and look thru the barrel carefully out a window for light. You'll see the light coming thru each corner of each groove. Sometimes even more open in the grooves showing  more light. That's open space where the lead isn't at the bottom of the grooves.

[FlyingZebra]

Thanks Rifle.

Procedure is to tram head with tenths indicator then indicate each chamber with tenths (.0001) indicator.
Reamer is left hand  helix, right hand cut - won't drive itself.

Gotchya on the chamber step.  Plan is to take cylindrical part of chambers to depth of deepest one of the six.  Varies by about .080" on that depth.
This is a 20 year old revolver.




-FZ