joeb33050
01-22-2006, 10:35 AM
Again, for the book, pictures only work on the CBA site, forum, files. Looging for comment, friticism, (yes, friticism, dammit!!), additions, personal stories, lies, what some guy told you, etc. This thing won't let me put it all here, so it's in 2 parts.
Fitting a Cast Bullet to the Chamber of a Firearm”
Bill McGraw, Ric Bowman
01/22/06
Recent RCBS, Lee, SAECO and Lyman moulds cast bullets that fit many/most guns well; Lyman moulds of older manufacture usually cast much larger than newer molds. There are other moulds made by NEI and many other custom mould makers, and there are many used moulds for sale at gun shows and other outlets. In most cases you can buy a mold that casts a bullet that shoots well in your gun.
Read a good loading manual before loading any ammunition. Follow directions, double check powder type and charges, and look into the cases to insure the powder level is correct before seating the bullet.
Revolver bullets must fit the cylinder throats, must be throat diameter (exact throat diameter or +0.003 inches maximum). If the bullet is smaller than the cylinder throat there will be gas blow-by, leading and accuracy will be destroyed.
If the forcing cone is slightly larger than the cylinder throats and tapers to the groove diameter, all is well.
If the barrel groove diameter is smaller than the cylinder throats, all is well.
But, if the groove diameter is larger than the cylinder throat diameter, problems well ensue. The only option is to have the cylinder throats reamed to bore diameter.
Rifle bullets must fit the throat, must be no more than half-a-thousandth of an inch smaller than the throat. The throat ( or "leade" or "ball seat") is the section of the chamber from the end of the case to the rifling. The point is that the bullet must make a seal to keep the gas from blowing by and depositing lead on the bore.
Fitting cast bullets deals with dimensions of chambers, throats and of bullets and bullet moulds. If the bullet is "too small", upon firing the gas will blow by the bullet, gas cutting the bullet and leading the barrel. The intent is to fit the bullets so that gas-cutting and leading is minimized, so that the gun shoots accurately, and so that SAFETY is maintained.
These dimensions are needed to fit a bullet:
For Revolvers:
a. cylinder throat diameter
b. barrel bore and groove diameters at the muzzle and end where the barrel screws into the frame
For rifles:
a. throat dimensions
b. barrel bore and groove diameters at the breech end and the muzzle end to see if there is any taper to the bore.
c. for rifles with a screwed-on or pressed-on sight or sling mount, bore and groove dimensions should be measured under the mount also
Instructions for measuring these dimensions are included in this book.
Additional considerations:
A larger bullet is better than a too-small bullet. The smaller bullet may not shoot without gas-cutting and eventual bore fouling.
Lever action rifles with tube magazines require flat-nosed bullets that are crimped in place. Pointed bullets MAY fire the next cartridge in line by hitting the primer.
Bolt action rifles may allow a tighter fit in the throat so as to allow the bullet to seat in the axis of the bore yet not so tight that the bullet will lodge or debullet if the loaded round needs to be extracted. Except sometimes bolt guns are more accurate when the bullet is seated way out, and the cartridge can't be removed from the gun without de-bulleting. Every shooter should and will pull the bullet out of the cartridge when removing a cartridge from the gun. The powder falls out of the case and immediately goes to everywhere in the action. Now the gun has to be disassembled and cleaned, and the bullet has to be knocked out of the bore. This de-bulleting is especially interesting if it occurs during a hunt, or a match.
In all firearms, some leeway in fitting must be considered if many rounds are to be fired in match competition when fouling buildup is expected and cleaning is not done until such competition is finished.
Loaded rounds should fit in a auto-load pistol and lever, slide or auto-load rifle’s magazine, if you load cartridges in the magazine.
I never load rifle cartridges in the magazine, I shoot all rifles one cartridge at a time. At the Old Colony Sportsman's Association in Pembroke MA. this is the rule, single loading always unless under a special dispensation (M1s, M1As, AR15s etc.).
Cartridges should chamber without having the bullet seated too deeply in the cartridge case. In the case of bottle-necked cartridge cases, the bullet base should be seated no deeper than the bottom of the neck if at all possible.
For bore-riding bullets, the bullet base should be of groove diameter and the bullet nose of bore diameter plus 0.001"-0.003”.
Lower velocity loads work well with the larger diameter bullets; higher velocity loads seem to work best with the smaller diameter increase .
There is much difference in chamber and throat dimensions from one gun to another.
End of part 1, go to part 2
Fitting a Cast Bullet to the Chamber of a Firearm”
Bill McGraw, Ric Bowman
01/22/06
Recent RCBS, Lee, SAECO and Lyman moulds cast bullets that fit many/most guns well; Lyman moulds of older manufacture usually cast much larger than newer molds. There are other moulds made by NEI and many other custom mould makers, and there are many used moulds for sale at gun shows and other outlets. In most cases you can buy a mold that casts a bullet that shoots well in your gun.
Read a good loading manual before loading any ammunition. Follow directions, double check powder type and charges, and look into the cases to insure the powder level is correct before seating the bullet.
Revolver bullets must fit the cylinder throats, must be throat diameter (exact throat diameter or +0.003 inches maximum). If the bullet is smaller than the cylinder throat there will be gas blow-by, leading and accuracy will be destroyed.
If the forcing cone is slightly larger than the cylinder throats and tapers to the groove diameter, all is well.
If the barrel groove diameter is smaller than the cylinder throats, all is well.
But, if the groove diameter is larger than the cylinder throat diameter, problems well ensue. The only option is to have the cylinder throats reamed to bore diameter.
Rifle bullets must fit the throat, must be no more than half-a-thousandth of an inch smaller than the throat. The throat ( or "leade" or "ball seat") is the section of the chamber from the end of the case to the rifling. The point is that the bullet must make a seal to keep the gas from blowing by and depositing lead on the bore.
Fitting cast bullets deals with dimensions of chambers, throats and of bullets and bullet moulds. If the bullet is "too small", upon firing the gas will blow by the bullet, gas cutting the bullet and leading the barrel. The intent is to fit the bullets so that gas-cutting and leading is minimized, so that the gun shoots accurately, and so that SAFETY is maintained.
These dimensions are needed to fit a bullet:
For Revolvers:
a. cylinder throat diameter
b. barrel bore and groove diameters at the muzzle and end where the barrel screws into the frame
For rifles:
a. throat dimensions
b. barrel bore and groove diameters at the breech end and the muzzle end to see if there is any taper to the bore.
c. for rifles with a screwed-on or pressed-on sight or sling mount, bore and groove dimensions should be measured under the mount also
Instructions for measuring these dimensions are included in this book.
Additional considerations:
A larger bullet is better than a too-small bullet. The smaller bullet may not shoot without gas-cutting and eventual bore fouling.
Lever action rifles with tube magazines require flat-nosed bullets that are crimped in place. Pointed bullets MAY fire the next cartridge in line by hitting the primer.
Bolt action rifles may allow a tighter fit in the throat so as to allow the bullet to seat in the axis of the bore yet not so tight that the bullet will lodge or debullet if the loaded round needs to be extracted. Except sometimes bolt guns are more accurate when the bullet is seated way out, and the cartridge can't be removed from the gun without de-bulleting. Every shooter should and will pull the bullet out of the cartridge when removing a cartridge from the gun. The powder falls out of the case and immediately goes to everywhere in the action. Now the gun has to be disassembled and cleaned, and the bullet has to be knocked out of the bore. This de-bulleting is especially interesting if it occurs during a hunt, or a match.
In all firearms, some leeway in fitting must be considered if many rounds are to be fired in match competition when fouling buildup is expected and cleaning is not done until such competition is finished.
Loaded rounds should fit in a auto-load pistol and lever, slide or auto-load rifle’s magazine, if you load cartridges in the magazine.
I never load rifle cartridges in the magazine, I shoot all rifles one cartridge at a time. At the Old Colony Sportsman's Association in Pembroke MA. this is the rule, single loading always unless under a special dispensation (M1s, M1As, AR15s etc.).
Cartridges should chamber without having the bullet seated too deeply in the cartridge case. In the case of bottle-necked cartridge cases, the bullet base should be seated no deeper than the bottom of the neck if at all possible.
For bore-riding bullets, the bullet base should be of groove diameter and the bullet nose of bore diameter plus 0.001"-0.003”.
Lower velocity loads work well with the larger diameter bullets; higher velocity loads seem to work best with the smaller diameter increase .
There is much difference in chamber and throat dimensions from one gun to another.
End of part 1, go to part 2