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A collection of comments and articles on the many aspects of bullet casting by various cast bullet shooters
Cast Bullets For Beginner And Expert
SECOND EDITION, 2007 - Joe Brennan
Chapter 2.0 Bullet Mold Selection And Design

     For most applications there is a cataloged bullet mold that will produce bullets with adequate accuracy in your gun. Most of the time a Lyman or Lee or RCBS mold will make bullets that shoot fine in your guns.

     For some guns and situations in which better accuracy is desired, it may be necessary to select or design a bullet mold for a particular gun.

     The bullet and the gun must be "matched".

     Rifle bullets must be large enough so that no gas can blow by the bullet, melt the sides of the bullet and lead the bore. Today's wisdom is that the optimum bullet diameter is about 0.0005” less than the throat diameter. For non-match use, 0.001" under- the diameter of the throat of the rifle is often serviceable too.

     Revolver bullets must be as large as the cylinder throat, the forward-most part of the cylinder.

     To match the bullet to the gun, we must measure certain dimensions of the gun, and then, using these dimensions, decide on the dimensions of the mold.

     The throat dimensions, rate of twist, bore, and groove dimensions are the important gun dimensions. 

     The length and the diameters of the various parts of the bullet are the important bullet dimensions. 

     Matching the gun dimensions and the bullet dimensions will generally improve accuracy. We are concerned with the rate of twist because a bullet that is too long for the rate of twist cannot be stabilized and thus will group poorly and may strike the target sideways.

     The following explains how to measure these dimensions and how they are inter-related.

Bullets

     Cast bullets have some or all of these parts: “Grease grooves” for the lubricant, “bands” or larger diameter sections before and after the grease grooves, a “base band” on the bottom or a “gas check shank” on the bottom to accept a gas check, a “nose” on the front of the bullet and a “meplat” that is the flat, however small, on a bullet's nose.

Rifle Bullets

     Many of the rifle bullet molds available today will produce bullets that will shoot accurately; some combinations yield exceptional accuracy. Standard molds will produce bullets with acceptable accuracy for most of your shooting. In the 30 calibers, the Lyman 311041, 311291 or 311299 shoot very well. While the 311041 and 311291 are not "bore rider" or "tapered" bullets, or any other trick shape, they shoot well and sometimes wonderfully in 30 caliber rifles, and have done so for about a hundred years.

     Rifle bullets come in a myriad of styles, suited for various applications. Some are unsuited to any application. Most successful rifle bullets are of one of these four styles:

     Single-diameter bullets are the same diameter on all bands. Examples are the H. Guy Loverin-style bullets such as the Lyman 311465 or 311466 and many Lyman designs such as the 319247 that has been popular for many years.

     Tapered bullets have bands that are about bore diameter at the front, and gradually get larger as they approach the rearmost band, which is several thousandths of an inch larger than groove diameter. Lyman made molds for tapered bullets in the past and other custom mold makers make them now.

     Two-diameter or Pope style bullets have front bands of bore diameter or slightly larger, and a rear band or bands which are a couple of thousandths of an inch over the

 groove diameter. This design is not as popular as it once was. Single shot shooters sometimes find that a Pope style bullet can be dropped in the rifle chamber, then the loaded cartridge case with perhaps a cork wad can be chambered, and that the rifle will shoot with great accuracy. There is a happy coincidence of dimensions that allows the case to seat the bullet.

     Bore-ride bullets have a nose that is at or slightly over bore diameter, and a base that is slightly over groove diameter.

     This design is quite popular today, and examples include Lyman’s 311299 and 311284. Some shooters have written that the bore-ride bullet must be a press fit in the barrel (at the muzzle) of the rifle for good accuracy. A helpful shooter at the range will sometimes take one of your loaded cartridges and try the fit of the nose of the bullet in the muzzle of the rifle. The shooter will then shake his head, and make a clucking noise. He will explain that your bullet is either: a. too loose, or b. too tight. Don't listen to the clucking, and don't worry about the fit. Good fit is nice, but poorly fitting bore-ride bullets may shoot well in light loads, sometimes with target accuracy.

     The difference between a sloppy fit and not being able to push the bullet into the barrel of the gun with your thumb is about one thousandths of an inch. 

     The chamber-end groove and bore diameters become larger than the muzzle-end diameters after not too many shots are fired in the rifle. The fit of any given bullet will vary with the rifle checked; it doesn't take much rifle bore and/or groove variation to make the bullet tight or loose. 

     The largest diameter of the 30 caliber bullet should be at least .002" and preferably .004" larger (my experience, others differ) than the groove diameter of the barrel at the breech end.

     Thirty caliber barrels (for the sake of argument) have bore diameter of .300” and groove diameter of .308”.

     The ideal 30 caliber bore ride bullet would then have a nose about .301” diameter to snugly fit the bore, and base bands about .310” diameter. If the breech end of the barrel is worn, the nose and body should be larger. Some barrels will accept bullets with noses of .303"- .304".

     Shooting a bullet that is too small in diameter for the barrel causes a lot of trouble. The bullet must be big enough! Leading of barrels at lower velocities, 1400-1600 feet per second or below, is almost always caused by bullets that are too small. 

     Today the conventional wisdom is that the bullet must fit the throat of the rifle. Harry Pope wrote that the bullet must fit the throat over 75 years ago. The throat is that part of the chamber between the end of the cartridge case and the rifling. The bullet should be as large as the throat.

     The more advanced cast bullet shooters have molds and bumping/swaging dies made to form the bullet to the shape and size of the throat, and chamber rifles for this tapered fit of the bullet to the throat. The rest of us can get good accuracy without leading by shooting big bullets.

THE LYMAN-POPE 308403

     This bullet was originally the Lyman 308403, and later the number was changed to 311403. According to Rudi Prusok, the ASSRA archivist, this bullet was first listed in the Ideal/Lyman handbook in 1927, and was listed until 1957-when the number was changed to 311403.

From the 1927 Ideal Hand Book:

“308403. Bullet designed by Mr. Harry Pope for extreme accuracy in competitive shooting in the .30 Springfield rifle. Should be used as cast and not resized. Diameter of first four bands from point .301”, fifth band .303, sixth band .305”, last band .315”. Bullet seated in case with fingers so mouth of case extends only half way up base band. Powder charge 12 to 15 grains Dupont No. 80 powder. This bullet gives better accuracy up to 200 yards than any combination we know of in the Springfield, but owing to the bullet being seated so lightly in the case, it is not suitable for handling except on the target range.

     Loring Hall has shot these bullets offhand very effectively in the Winter League matches at the Old Colony Sportsman’s Association in Pembroke MA for many years, in one of his 30/06 Hammerli Team Rifles.

     I’ve borrowed a mold for this bullet several times from Pete Ziko, a member at Old Colony, and cast a thousand or so bullets each time. Pete absolutely refused to part with the mold. These bullets, at lower velocities, have shot accurately in a number of 30 caliber rifles that I’ve owned.

     Recently I’ve borrowed molds from John Greene, to cast some additional bullets. John made the mold I borrowed from him, a very nice piece of work. He has the cherry and can supply molds.

     The trick to this bullet is that the base band is tapered smaller at the rear-larger at the front; and the dimensions are made so that the bullet slips into a fired 30 caliber case and wedges itself to a stop about half way up the base band. To reload: deprime and reprime, throw a charge of powder and seat the bullet with your fingers. No sizing of the cartridge case or bullet is required. I find that chamfering the inside of the case mouth helps in seating the bullet.

     Here are some typical 100 yard groups with the 308403 with Darr lube, Winchester M54 30 WCF, 30X STS, 6.8/Unique, Dacron wad, WLP primer.

Revolver bullets

     The accepted wisdom on revolver bullets is that the diameter of the bullet must be equal to or .001" greater than the diameter of the cylinder throat. The cylinder throat is the most forward part of the cylinder, where the chamber narrows. Tapping oversize slugs through the cylinder throats of the revolver and measuring them will give you the throat diameter. Oversize slugs can be made by tapping a proper sized (= 44 bullet for 44 gun) bullet nose with a hammer or squeezing it in a vise. Either method will expand the bullet.

     If the bullet is much less than the cylinder throat diameter, the barrel will lead and accuracy will fall off. With any reasonable middle velocity load, a good lube, and a correctly sized bullet; the revolver won't lead. Higher velocities can be attained by fiddling with the powder charge, lube and bullet hardness.

     Most often a revolver bullet doesn't have to be too hard.

     Some revolver bullets are made for gas checks. I agree with Elmer Keith on this, we never, (almost never), need a gas check on a revolver bullet.

     Revolver bullets come in many styles. Here are examples of the most popular.

     This is a round nose bullet, found in some factory loaded ammunition. This style of

 bullet has nothing much to recommend it, it is not very accurate and is not particularly suited for hunting.

     Here is a wadcutter with a hollow base. This is the most accurate bullet for  short range = up to 50 yard shooting with a revolver. This style bullet is factory loaded and reloaded quite commonly.

     These are the hollow base and standard versions of the Elmer Keith designed 44 Special and 44 Magnum revolver bullet. There is also a version with hollow point. This bullet, the Lyman 429421,(429422 in hollow base), has proven to be quite accurate and quite a good hunting bullet in the 44s. This is called a semi-wadcutter style bullet. I'm not much of a pistol shooter, but I've had very good luck with this bullet in 44 Magnum pistols over the past 40 years or so.

 

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Warning: All technical data mentioned, especially handloading and bullet casting, reflect the limited experience of individuals using specific tools, products, equipment and components under specific conditions and circumstances not necessarily reported in the article or on this web site and over which The Los Angeles Silhouette Club (LASC), this web site or the author has no control. The above has no control over the condition of your firearms or your methods, components, tools, techniques or circumstances and disclaims all and any responsibility for any person using any data mentioned.

Always consult recognized reloading manuals.

 

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