By Mark Trope & R. Ted Jeo

WARNING!

This article contains information on reloading ammunition that requires a fair amount of reloading experience. We would not recommend this technique to a beginning reloader. This technique works for our weapons and reloads. As we have no control over others shooting needs, techniques or materials, we cannot assume any responsibility if you decide to use the technique on loads discussed. As always, reloading ammunition is a serious undertaking and needs to be carefully examined at each step to make sure all safety precautions and inspections are adhered to.

Surplusrifle.com's Site Disclaimer

As stated above, cast bullets are much softer then jacketed. Even the strongest and hardest cast bullets are only 1/3 as strong as their jacketed cousins. To resist deformation and gas cutting (where the hot powder gases melt and/or deform the lead), a cast bullet must be larger then bore diameter. After determining bore diameter and adding .002”, the correct bullet sizing kit or sizing chamber can be selected. (For information on sizing & lubing options see the article "Intro to Lead Alloy Bullet Casting for the Mil-Surp Rifle”).

Two changes in the reloading process must be addressed when using cast bullets. Since cast bullets are softer then jacketed, it becomes necessary to open the edge of the case mouth to accept the cast bullet without shaving lead as the bullet is seated (you will see this in the form of a thin crescent or ring of lead right at the mouth of the case after you have seated a cast bullet). To accomplish this, one step must be added to the normal loading process. A flair or expanding die must be used to gently flair the case mouth. Lee has recently introduced their Lee Universal Case Expanding Die. It will work for all calibers because of its interchangeable expansion plugs. Prior to the introduction of the Lee die, an individual flair die would have to be acquired for each family of calibers. A nice point about the Lee die is the “self centering” feature which rigid flair dies lack. At about $10.00, the Lee die is truly a bargain.

The second point about loading technique is the depth to which a cast bullet must be seated for good accuracy. Because cast bullets are not as hard or strong as jacketed bullets, it becomes necessary to start them into the chamber and barrel lead without any free travel. Because of cast bullets being softer, no excessive pressures will result from this practice. To determine the required Over All Length for a cast bullet cartridge in a particular rifle, see the article “Making the Surplus3: Measuring Cartridge Over All Length (OAL) in a Mil-Surp Rifle.” The exact process Ted and I describe in the above article can be used for cast bullets EXCEPT the bullet will not be backed away from the barrel lead at all. The cartridge will be left full length, so the bullet is pressed against the lead. This will give it a straight start into the barrel.

By the way, the shooting technique with a mil-surp rifle is a bit different from shooting a more “modern” rifle. The reason is the older rifles have a longer lock time, and many have a two-stage trigger. Neither of these conditions is by accident, and neither is a liability.

The longer lock time allows a longer and harder/heavier firing pin strike. The heavy firing pin strike is good insurance for ammo produced under wartime conditions, which may have to be fired in frigid cold or blistering heat with sub standard quality primers.

The two-stage trigger is another safety built into the old rifles. The last thing an army wanted was for an exhausted, cold and jumpy recruit to blunder into a crisp trigger and have an accidental discharge!

The best bench shooting technique for a mil-surp rifle is a two-step process. First, hold the rifle firmly with both hands; pull it down hard onto the sand bags. Second, pull it hard against the shoulder and keep it there.

The last subject we will look at are powders and powder positioning in cartridge cases for cast bullets. Most of the loading data for cast bullets use fast to medium powders. This is because most cast bullet shooting is at somewhat reduced velocity. This is a good thing; it strains neither the old rifle nor the old shooter’s shoulder and minimizes the amount of lead left behind in the barrel. The Lyman and RCBS Cast Bullet Manuals show one of the most used powder is IMR 4198. This is an extremely versatile powder.

In comparing the best powders to use for jacketed vs. cast bullets, the basic idea is that slower burning powders work better for jacketed and faster powders for cast bullets. The idea is that if you fill the case (to max load density) with a slower powder under a cast bullet, which develops less pressure because the bullet easily deforms to the barrel, you may very well leave a trail of unburned powder down your barrel. In contrast, a jacketed bullet, which develops much higher pressures, likes the slower powder and has the time before the bullet leaving the cartridge for the slower powder to completely burn. Remember, the harder jacketed bullet will resist deformation more than the softer cast bullet. So, we want to use a faster powder, which will fill the cartridge less. This offers a problem though.

Have you ever noticed when buying commercial factory or mil-surp ammo that the powder almost fills the case completely? This is no accident. Loading density is the term for the percentage of the case, which is occupied by powder. The closer to 100% loading density, the more efficient the cartridge will be. The loading company selects a powder, which will perform within established velocity and pressure standards, while filling most of the cartridge case.

It is very likely that in using a fast burning powder and a cast bullet combination, you will have a cartridge that has a lot of empty space in it. If the powder is this type of reduced load (reduced in the sense of not filling the cartridge to near 100% loading density), it will lie on the bottom of the case when the rifle is held horizontal to fire. This situation is not desirable. It causes the flame of the primer to travel across the top of the powder charge. Since smokeless powder is “progressive burning” the most efficient position for the powder is against the flash hole.

In the distant past, various methods were tried to hold reduced loads against the flash hole. They all had disadvantages. Some were even dangerous. About 20 years ago, Winchester released for sale, to the general public, a synthetic powdered material that they loaded in their shotshells. Experimenters found by loading this material on top of reduced charges of fast burning rifle powders in rifle cases, 100% loading density could be achieved with cast bullets. They also found it was a real boon to accuracy, and barrel cleanliness! Unfortunately, Winchester discontinued selling this product many years ago.

However, we now have an even better replacement. Precision Reloading, Inc (www.precisionreloading.com).  sells a product called Precision Spherical Buffer, (PSB).

Peter Maffei, President of Precision Reloading, Inc., kindly took time out to his busy schedule to answer questions about PSB. He advises that: “ PSB is a proprietary product-mixed to our specifications and purchased in 20,000 pound lots. We did extensive R&D on the product and developed the perfect product for our application.”

PSB granules are perfectly round. Matter of fact, it is so perfectly round that having accidentally dropped a bit on the benchtop, when I put my caliper down on top of it, the caliper “floated” away on the tiny beads as if it were floating on air. PSB glides right through powder measures, or can be dipped with Lee or homemade dippers. A reduced cast bullet load, developed with PSB, has all the qualities we are looking for. Safe, easy to acquire & use, 100% loading density, accuracy enhancing and scrubs the barrel clean with each shot. Ok, sounds good so far, but, how does it work? Before we can answer that question we need to examine the nature of barrel leading.

When a cartridge is fired, hot gasses can literally burn off some of the lead from a cast bullet and turn it into vapor. This process is known as “gas cutting”. The lead vapor will adhere to the inside of the barrel. The bullet can become eccentric and be thrown out of balance. The resulting group will be larger on the target then if the bullet had retained its proper shape and concentricity. But, it gets worse! Once leading begins in a barrel, it spreads fast. Lead has an affinity for itself. As another bullet moves past a spot where a previous bullet has left lead, that new bullet will have lead pulled from it also. While most cast rifle bullets have a gas check (a thin copper base) to protect the heel of the bullet, they can do little about gas cutting on the bullets side.

Enter PSB. PSB placed on top of a reduced charge, to a level where the bullet, when seated, holds the powder charge and PSB under slight compression will give us the 100% loading density we seek, and keep all the powder against the flash hole.

Upon firing, the PSB protects the bullet from the hot powder gasses, so no gas cutting occurs. As the PSB moves down the barrel behind the bullet, it has a scrubbing effect, literally cleaning the barrel of powder residue with each shot. But, it gets better! The PSB also leaves a micro thin coating on the lands & grooves of the barrel. Every bullet is riding on that coating; however, the material does not build up, it is replaced by a coating from the next shot. Dramatic increases in accuracy can be had with PSB. I have a Spanish FR8 Mauser, caliber .308 Winchester, which I use for mil-surp Metallic Silhouette shooting. The barrel has not been cleaned in over 3 years, and there is no need to, and it stays clean from PSB loads! Of course, only PSB loads are fired through the rifle.
 

The .308 Winchester is a good, medium capacity cartridge. Medium capacity cartridges seem about perfect for loads with PSB. Other medium capacity cartridges include 8mm Mauser, 7mm Mauser, the various 6.5 mm mil-surp rounds, 7.62X54R etc.

Ok, let’s look at a practical application of this discussion. First, we establish the maximum OAL for a cartridge with a given cast bullet. Next consider the total weight of that cast bullet (including its gas check). In our .308 example, I am using a Seaco mould, # 301, which casts a .30 caliber bullet, which, when gas checked, weighs 198 grains. A look at the current Speer Manual, #13, shows a load of 24 to 28 grains of IMR 4198 may be loaded with a 200 grain jacketed bullet. So, the Speer Manual, which is the manual by which all others are judged, says it is safe to load up to 28 grains of IMR 4198 with a jacketed bullet with a Brinell hardness of 100. We will load a cast bullet, which is only 1/3 as hard, so we should have a lot of leeway to work with. Now, from previous loading experience and trial and error (something only you can do for your rifle and needs) I have determined that a load of 21 grains of IMR 4198 works for my rifle/bullet combination. The addition of the PSB filler follows.

First, you will need a good idea how far the bullet is seated down into the case. You can accomplish this calculation from your OAL value compared to just the length of a cast bullet. The difference would be the distance to the bottom of the cast bullet. You may want to use your caliper to get a good idea where this is in relation to the inside of your case. The idea is to get it close to the bullet and to LIGHTLY compress the PSB between the powder charge and the base of the bullet. For this reason we want the filler to be a tad higher is so we have a compression factor when the bullet is seated, this very important. When seating the bullet, hearing a very slight crunch as the bullet is seated tells us we have our compression factor.

WARNING (again)

Reloading is a very serious business. It is not to be taken lightly. One must totally understand the issues involved before taking the plunge. The work discussed here is safe, provided one adheres to standard safety practices. However, since we have no control over the actions of others, their components or their tools we assume no responsibility if one chooses to use loads or materials discussed.

Surplusrifle.com's Site Disclaimer