C&B cylinder internal ridge

[JohnLeePedimore]

Does anyone know why my magnum C&B revolver has a ridge in the cylinder that keeps the bullet from being seated deeper?

Thanks.

[TwoGunJayne]

Yes!

This topic has actually been discussed a bit here!
http://naaminis.com/smf/index.php?topic=4605.msg75207#msg75207

It's deceptively high tech, similar to one of the most advanced black powder weapons....

http://www.musketeer.ch/blackpowder/handgonne.html

The Tannenberg Gonne. A secret weapon, the only known prototype was thrown into a well near an armory to keep the secret.

In BP, having a narrower powder chamber than the bore diameter improves powder burning efficiency. More bang, less buck (you're saving powder.) They're very highly efficient.

Added plus? It keeps you from compressing your powder and causing erratic chamber pressures. It has the advantage of consistency. It also permits more and more finely ground powder to fit in the chamber for a given accurate volume with little to no concern of breaching the powder chamber walls.

http://www.handgonne.com/tann2.html
http://www.handgonne.com/tanberg2.html

I was quite surprised to see this design element in a currently available BP device. Most makers either don't know about it or won't touch it.

Just about the only limitation the design has is that it basically caps your max charge without getting all "wonky." It basically hard-caps your max accurate load, the shot will be all over the place once the powder crests the powder chamber on an overload.

[TwoGunJayne]

Oh yeah, forgot to mention...

Since the NAA Cap and Ball is very highly miniaturized, it's not good to use modern smokeless. It'll probably cause a failure.

Even so, it's a great design element for any black powder gun, in my opinon. You'd think the BP rifle makers would want in on this.

I had a .17 toy BB cannon that used this chamber design... with flash powder. Alas, I no longer have it. Most straight-wall .17 toy cannons need 4F BP.

[JohnLeePedimore]

Thanks for the info.

[TwoGunJayne]

Anytime, sir. Don't head off too quickly. We talk about some guns here.

[scbuxton]

The breech of my lyman GPR is conical at the bottom, smaller than the bore, similar to the above described design. No wonder that it does so well. 60 grains of 3f goex and it zings. Oh, don't want to forget,  welcome to the forum,  johnleepedimore. Copperhead road is one of my favorites, great handle.

[Uncle_Lee]

Just make sure you fill that smaller portion of the chamber up with powder.
If you don't, you will leave an air pocket and your bullet/ball may act as a barrel obstruction.
With black powder you always want the bullet/ball against the powder or with a small amount of compression.

[trotterlg]

I have also heard you need compressed BP charges only also. No air gap in the chamber.  If you fill the smaller portion of the barrel things would be good, but I can see that a half charge could cause problems.  Larry

[TwoGunJayne]

The stock NAA bullet for C&B is hollow base, increasing the chance of a slight air gap.

Crimping #4 buckshot into the chamber will compress the powder more, all but eliminating the chance of an air gap.

Due to ballistic properties, most people find conicals to be more accurate than roundball. In my personal NAA C&B, I found the reverse was true.

http://naaminis.com/smf/index.php?topic=3182.msg49526

The basic lack of chance of an air gap and the extreme evenness of the swage/crimp of the #4 buck tightened my groups. The chrono showed the #4 buck load to be far, far, far more velocity consistent than the stock bullet. If I'm not shooting 21 grain .22 pellet rifle pellets loaded backwards and filled with T&C Bore Butter, then I prefer #4 buck. Remember to crimp the pellets in well or you'll get a reduced pressure load. When you use pellet rifle pellets, you absolutely positively must seal the chamber with something like Crisco or Bore Butter or you're going to get a chain-fire!

.22 pellet rifle pellets are slightly undersized with respect to .22 firearm caliber. This is to help frustrate those who wish to convert airguns into firearms. With the skirt of the pellet being the "nose" of the hollowpoint, squashing it down is the only way to get enough backpressure to light evenly and consistently.

Pellet rifle pellets took an armadillo for me. The chrono says they're not very consistent. I don't expect much from the smallest NAA cap and ball guns with a pellet. The 4" handles them well and they're pretty accurate for what they were. I had zero expectations when I first tried it, and there were a few failures along the way.

I've tried to share what I learned in the process.

1. Crimp well, in fact, do it twice just to be sure. A poorly seated bullet won't perform well at all in a C&B.
2. FILL the remainder of the cylinder chamber with your grease. Squish it in with a plastic knife or something. I fill it flush. I'm allergic to chain fires and I'm sure my revolver is as well.
3. Inspect the chambers as you fire as firing can blast out some of the sealant. It's a judgement call on whether or not you reseal them before the chamber is over. I make it through all 5 in my gun, but I haven't tested yours.
4. Your mileage may vary, offer void where prohibited, you might get keyholing from a barrel shorter than 4". Mine doesn't really do it, except perhaps towards the end when there is less sealant due to gun gasses blasting everywhere.

If you hit something armadillo/opossum/raccoon sized with this loading, it's probably not going to exit as the pellet skirt is going to expand like crazy due to the Bernoulli effect. This means 100% energy transfer. Some think this is optimal.

One of the reasons the pellets seem to go to flat little bits is that greased hollowpoints expand more quickly upon impact with a fluid medium and it helps resist failure due to hollowpoints plugging with cloth fibers, hair, or whatnot. That's an old, old trick right there.

Other reading:
http://www.thehighroad.org/archive/index.php/t-121900.html
http://thefiringline.com/forums/showthread.php?t=7191
http://smith-wessonforum.com/ammo/259473-filling-hollow-point-bullets.html

[Uncle_Lee]

"Due to ballistic properties, most people find conicals to be more accurate than roundball. In my personal NAA C&B, I found the reverse was true."

I also find balls to be more accurate.