Navy Six,
Thank you.
Do you have any problem with the 5 cavity filling out? I have a 147gr 9mm 5 cavity aluminum mold from him and it takes me while to get wrinkle free and pretty bullets. It really doesn't matter as much since I am powder coating them, but I'm almost borderline OCD and wrinkled bullets don't sit well with me. They are also grooveless which I think adds to the heating problem (plus that long bearing surface shows any imperfection).
I have no doubt a Uberti Navy of any type (like yours) doesn't have any trouble clearing the rammer or the opening. That's what all of mine are, I have two '51s, two '61s and a pair of Leech & Rigdon revolvers. The guys who were reporting loading area problems when we were polling everyone back in '09 had Brass framed frankenpistols of dubious origin. I didn't believe one guy until he sent me a picture with a caliper showing me the gap distance. Your revolvers would have cleared the original design with the wider groove (more lube).
I'm sorry you have that taper. Some people report that and unfortunately the Ubertis appear to have it more than the Pietas or even the Armi San Marcos. I like the grip shape and finish of the Ubertis better but they almost all suffer from short arbors and too many have tapered chambers. Do you ever have the bullets move forward from recoil (kind of laughable in a .36 C&B)? More common with balls than bullets with more bearing surface.
It sounds like your revolver(s) are good candidates for a chamber reamer. Do you have one revolver or two? You only need to do the first 0.50 Inches. If you have 2 then ream them both the same and 0.001 inches larger than what you have as your largest diameter to get a fresh clean surface. With your reported Ø.372 measurement I would ream it to Ø.373.
Almost all production reamed chambers will ream tapered (except through bores). .002 is acceptable, .006 is a bit excessive. I do have a question for you though. When you say you have taper, do you mean taper or a stepped chamber? Almost all Percussion revolver cylinders are stepped, this includes the originals. You don't need more than 1/2 inch to be true and with very little taper.
I guess I lied, I actually have a few more questions:
- How are you measuring the bore at the mouth?
- How are you measuring the diameter at the bottom?
- Are the two measurements just the maximum and the minimum?
Look at Attachment #1 below, that is one of my '61 cylinders I just grabbed. Those gauge pins are Ø.371 for the one sticking out further and Ø.364 fro the deeper one. The deeper one goes almost all of the way to the bottom of the second stepped hole. You can't go further unless you use a smaller pin because you are in the area of the rough finish from the end of a blind reamer pocket. The larger pin is sticking 0.504" down into the chamber. The last pin I'm not showing but it is a Ø.373 pin and just fits inside the bore, so I call that a .002" total taper for 0.504" That is good for an Italian Percussion revolver.
Look at Attachment #2, that is actually a model of a '60 cylinder but the .36 calibers are the same, just smaller in diameter. Notice how it has the smaller stepped diameter that is Ø.4409 and I actually reamed my 2 sets of '60s to Ø.4505 measured diameter with a Ø.4500 reamer. I was running them 0.7 deep and the 6 chambers on one cylinder averaged 0.0706". I wanted to show you the step, it's not always obvious when looking down the chamber.
I also think you are going to more trouble than you need to. You said you first size Ø.375 (what is your "as dropped" size?), then size just the bottom to Ø.370. I'm curious how you size just the bottom and get it back out of the sizing die without tearing the bullet up. You can only go part way and it will be stuck pretty good with a swaging of .005".
Have you tried just seating the lubed bullet with your bullet seater? No sizing, just use them as molded. The design was made to shear off two rings. I'm not sure if you actually have taper (or should I say a full taper of .006"), it is probably less. You should determine if you are measuring the step diameter and calling it taper.
So Consider this:
- With the bullet we are talking about you only have a bit more than 3/16" of bearing engagement from the bottom of the first band to the top of the first where the ogive starts
- With the 19gr powder load you reported, FFFg will fill your chamber to about .420 below the face of the cylinder
- Your bullet is .475" long
- So you will have to have a minimum of .055" compression to even be dead flush with the face
- You should probably run at least a 1/32" below the face,
That is running it close. When you reported 19gr I actually thought "he's a better man than I". I actually load off of the revolver with a loading stand and I think I can get a 3/32th below the face with 16gr (powder starts out a bit over 1/2" below) and I always want a safety margin with a loose powder revolver in case I get bullet movement. If you truly do have tapered chambers that is more of an issue because bullets back out and will lock you up.(ask me how I know...)
~Mako