How and why to select effective cast bullet O.D.?

[Naphtali]

When buying a mold or sizing cast bullets intended to be shot in revolvers, do I want to focus on I.D. just forward of each loaded cartridge in chamber, or barrel's throat I.D., or barrel's bore I.D. to achieve consistent accuracy with less leading? Why?

[mpmarty]

The poor boolit in a revolver is faced with many dangers. The chamber mouth must be as large or slightly larger than the forcing cone. The forcing cone needs to be bore diameter or a thousandth of an inch larger. The boolit needs to be at least as large as the bore diameter (slugged) plus one or two thousandths. Most revolvers don't even maintain the same dimensions for all chambers, let alone meet all the above criteria.

[mooman76]

And if your chamber mouth is smaller than your barrel you got big issues with lead bullets. You would have to ream the chamber mouth to make it bigger or you will get terrible leading.

[HeavyMetal]

mpmarty states it pretty plain!

Most production revolvers have a bunch of tolerance issues. Some of these we can overcome during reloading others we can't.

In revolvers I find a boolit that is a tight fit in the chamber mouth is the best solution provided the chamber mouth is larger than bore size.

In the 44 magnum if the barrel is 429 the chamber mouths need to be 430. You can have them opened up if they are smaller, larger you just cast a bigger boolit.

This is about the best the average reloader can do without plopping down a bunch of cash for custom work.

Many guys do that or learn the skills needed to do the work themselves. In the end it's what you want the gun to do and what are you willing to pay to get it to do that!

[Larry Gibson]

When buying a mold or sizing cast bullets intended to be shot in revolvers, do I want to focus on I.D. just forward of each loaded cartridge in chamber, or barrel's throat I.D., or barrel's bore I.D. to achieve consistent accuracy with less leading? Why?

Size to the "throat". The throat in a revolver is that part in front of the loaded cartridge as you mention. Many times our cast bullets are not "as cast" diameter as larger as the throats. Simply size "as cast" then. Truth be known I shot a whole lot of .429" sized 429421s out of several .44s quite accurately for quite a few years. This was before I was educated by several gun publications and the forums. Then all the expert advise was that revolvers wouldn't shoot accurately with "undersize" bullets.

I then measured the throats on the two .44s I had. Yowza! The throats ran .430" - .432". I then got a .431 sizer and was basically sizing the 429421s "as cast". Those .431" sized bullets don't shoot any better but they sure do fit the revolver throat better.

I give the above example because "it depends". If you are using a soft alloy and/or the revolver throats are grossly over sized as in many .45 Colts with .454-.456" throats and a .451-.452" barrel then having the bullet fit the throats is a sometimes more accurate. If the throats are smaller than the barrel groove depth then even sizing to the throat will not help.

Unless you can shoot a revolver as 44man can then simply size your cast bullets as close to the throat diameter as you can. Many times simply "as cast" diameter is as close as you can come short of a custom mould or cylinder.

Larry Gibson

[Naphtali]

Many thanks, guys. I anticipate most common quality control problems to not be present -- Freedom Arms M97, M83s, and Ruger SRHs appear to have superior consistency.

My shooting partner is upgrading his sizers from a Star and Reddings, and RCBSs to a Ballisti-Cast. I'm buying his Star and heater, but no dies.

[looseprojectile]

44 Man knows the meaning of words such as;

Bore.
Groove.
Throat.
Freebore.
Bullet seat.
Twist rate.
Velocity.
Alloy/softness/hardness/composition.
Pressure.
Boolit lube. And there are lots of other words that are abused. This forum IS the Seminar.
And i think few here can put all those together as well as he can. Words have meaning.
I still try.

Life is good

[jforwel]

If you have throats that are undersized then it's no problem to have them opened up. Make sure to slug your bore first to get the proper groove diameter. I have had four cylinders reamed by http://cylindersmith.com/ with great results. Cheap and very fast turn around.

For example my Single Six had a groove dia. of .313 but the throats were .312. Now they are .314. My .41mag BH throats were .409 and are now .411. I shoot .412 boolits in it with fine accuarcy.

A set of pin gauges is very useful if you have several revolvers needing measuring or for buying new or used guns.

And as stated above boolit hardness is a whole 'nother thing.

[azrednek]

I got a Ruger 45 Blackhawk convertible for Christmas. The 45ACP loads that group real tight out of my S&W are all over the target out of the Blackhawk. The Ruger's cylinder mouths mike as small as .449. I complained to Ruger about at their booth at the NRA Convention and was basically told tuff sh!t. As long as it is within industry standards for jacketed bullets they wont fix it. The rep is correct, it does shoot much better with jacketed bullets, especially factory 45 Colts but I consider the revolver pretty useless until I get the cylinders reamed. I came right out and asked the rep if Ruger would ream the cylinder to .452 and was told "no sorry, you will have to find a bullet that works well and most likely it will be jacketed".

Some internet chatter I've read claims Rugers also have a tight spot in the portion of the barrel inside the frame that may also have to be opened up to .452.

[Bob Krack]

If there were a way for me to snap my fingers and make my revolver diameter measurements perfect, I would:
find the groove diameter (which is larger than the bore diameter)
make the forcing cone 1 or 2 thousandths larger than the groove
make the throats 1 or 2 thousandths larger than the cone
make the boolits 1 or 2 thousandths larger than the throat

Bob