Collecting and Shooting the Mil-Surp Rifle - Slug, Measure, & Match: Using the Right Bullet for the Right Barrel Diameter

Using the Right Bullet for the Right Barrel Diameter

The world of mil-surp collecting is like the proverbial box of chocolates, �You never know what you�re going to get�.

A Little Bit about Cleaning

At a gun show the first thing one normally does is take out his bore light and peer down the bore of a rifle. If there is a copious amount of rust, or the rifling & crown is so worn it�s all but non-existent, the rifle goes back on the table and one moves on. However, let�s say the rifling is strong, with sharp lands, which follow out to the crown. The rifling may be a tad dark, although that in of itself means little. The crown is in good shape, so far so good. The rest of the rifle is clean, the safety works, the trigger pull crisp, and the stock sound. Negotiations ensue and soon a happy buyer is on his way with a new treasure.

A responsible owner will field strip a new acquisition and give it a complete cleaning prior to shooting it. The barrel requires special attention. Most mil-surp barrels have amazing amounts of gliding metal & coupro-nickel jacket material and powder fouling. These materials are usually built up in alternating layers on both lands and grooves. A quick brushing with standard solvent will not get it anywhere near clean!

Stronger medicine is needed. One can either use a commercial or homemade electro-chemical cleaning device. These devices work well, and take out a lot of the �elbow grease� required for cleaning. Strong chemicals designed to aggressively dissolve fouling are another option. Products like Sweets 7.62 or Barnes CR10 work extremely well. Their instructions must be followed to the letter, and repeat treatments may be required. However, eventually they will get under the accumulated gunk in a barrel. One other option remains, mechanical cutting by means of a product like J-B Non Embedding Bore Cleaner. This last option requires a lot of handwork, and, if not done correctly can excessively wear rifling in that all important crown area.

Be forewarned, some milsurp barrels, even after all the jacket and powder fouling is removed will still emit tiny black specs when soaked in standard solvent after a range session. Smokeless barrel steel from 50+ years ago and older was mostly chrome moly. The steel has many impurities in it from the original manufacturing process of the time. These impurities will leach out during the cleaning processes once the balance of jacket and powder fouling is removed. I have a Turk Mauser, which is a very good shooter, but it emits black specs every cleaning. So, some barrels will never be spotlessly clean! Very old black powder rifles have soft, mild steel barrels which should only be used with cast lead bullets, jacketed bullets will wear them out in short order.

Enough about cleaning and such for now. Realize that the technique described below will start out with as clean a barrel as you can get.

Why We Need to Know the REAL Diameter?

Now let�s address an issue that many mil-surp RELOADERS run across once they have cleaned up their new toy and are looking to reload for their rifle. You go to look for bullets and you pick up 8mm (.323�) bullets for that Mauser. This one is pretty common and easy to find. Okay, I am sure that many of you realize that 8mm Mauser is actually 7.92mm. But, how about that 6.5mm Carcano? �Normal� 6.5mm is .264 inches. The 6.5mm Carcano is actually .268 inches. What happens when you fire .264� bullets in a Carcano? Well, some people have reported anything from good to down right terrible shots. (See the �A Carcano Comes a Knocking� article). The No. 4 Enfield is another rifle that should be .303� (right?). Many of the barrels are anywhere from .310 to .314 in diameter. One more for you. The M95 Steyr straight pull action rifle says �8mm�. Is it 7.92mm like the Mauser? Nope. It actually runs about .329� which is 8.36mm. There are more examples out there, including some Mosin-Nagants whose 7.62mm (.308�) barrels may range from .307� on the small side to .313� on the large side . The biggest issue of using the wrong bullet (too small) is a loss of accuracy. DO NOT EVER USE TOO LARGE A BULLET. This can result in high pressures and could result in injury, to you and your weapon (as shown in Figure 1).

How Can Lead Affect Your Health

The effects of Lead are the same whether it enters the body through breathing or swallowing. The main target for Lead toxicity is the nervous system, both in adults and in children. Long-term exposure of adults to Lead at work has resulted in decreased performance in some tests that measure functions of the nervous system. Lead exposure may also cause weakness in fingers, wrists, or ankles. Some studies in humans have suggested that Lead exposure may increase blood pressure, but the evidence is inconclusive. Lead exposure may also cause anemia, a low number of blood cells. The connection between the occurrence of some of these effects (e.g., increased blood pressure, altered function of the nervous system) and low levels of exposure to Lead is not certain. At high levels of exposure, Lead can severely damage the brain and kidneys in adults or children. In pregnant women, high levels of exposure to Lead may cause miscarriage. High-level exposure in men can damage the organs responsible for sperm production.

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Figure 1. Three rifles that have �weird� bore sizes. From top, M95 Steyr, No. 4 Enfield, and M38 Carcano.

So, why do we see these odd sizes that fit the standard? Well, one of the reasons is that many mil surp rifles were made with rather casual tolerances in the chamber and barrel. For military purposes this is a good thing. Ammo may have to be fired in the frigid winter or very hot summer, and still produce safe pressures. Some ammo was designated as dual purpose, having to serve both the rifleman and light machine gunner. Making a rifle chamber and barrel on the large side of the specifications kept pressures down and make it easy to chamber a round.

The �How To� of Slugging a Barrel

How do we find the best size bullet for a barrel? The answer is, Slug, Measure & Match. Best of all, this process is quite simple and inexpensive (of course!). The materials are available from a hardware store, a home center, or even a discount department store and a fishing tackle supplier (as shown in Figure 2).

Figure 2. Nothing very special with the items that you need. A few dowels, a few lead sinkers. Total cost (assuming you have the tools) less than $5 from your local hardware and sporting goods store.

Materials

1) A couple of hardwood dowels just under bore diameter. It must be long enough to go completely through the barrel, with at least 4 inches sticking out when the bolt is closed. A 1/8� diameter dowel can be used for 6.5mm and a �� diameter dowel can be used for 6.5mm and up.

2) A lead egg shaped fishing sinker slightly over groove diameter. 1/8� diameter (size #10) can be used for 6.5mm and �� diameter (size #9) for 7.62mm and up sized barrels.

3) Gun grease (Shooters Choice High Tech Grease as an example) and/or gun oil.

4) Old soft towel.

Tools

1) A micrometer will be required to measure our test slug. Most micrometers are accurate to .0001�. A caliper can be used, however none are accurate to more then .001�.

2) A soft faced plastic or rawhide mallet. NOTE: a small metal tack hammer MAY be needed at times, depending on how pure your lead sinker is.

3) Tape measure and marker.

Start out by clamping the rifle firmly in a vertical position. Realize that you will be literally pounding one end of the rifle, so make sure it is very secure. Place the towel around the base of the rifle to catch the lead sinker. You want to avoid dropping the slug as it deforms easily (as shown in Figure 3).

Figure 3. Clamp your rifle in really good. The rifle being used as example is a M95 Steyr carbine in 8mm (or is it really?) Note, dowel is sticking out barrel, ready to be marked and cut.

With the bolt closed slide the dowel rod into the barrel until it hits the bolt face. Now with the tape measure decide where to cut the dowel so its end is about 4 to 5 inches into the barrel. Remove the dowel and make that cut. Take a second dowel (usually around 36� long and cut it into 6� lengths. If you were to use a 1/8� or �� diameter dowel in very long sections, it would surely break. By using it in short non flexing 6 inch pieces it is less likely to break) (as shown in Figure 4).

Figure 4. Using a mini miter box and saw is not required, but nice straight edges on the dowel are nice.

We have already cleaned our barrel clean as per the previous discussion. Give interior of the barrel a light coat of gun oil. This will help our sinker slide out. Slide the long piece of dowel rod back into the barrel from the breach, then replace & close the bolt. Using the grease, cover the sinker with a generous amount. Also add a bit around the inside of the muzzle. Take the soft lead sinker and tap it into the muzzle with the mallet. Depending on the purity of your lead sinker, you may have to CAREFULLY use a metal tack hammer to get the sinker going into the barrel. Keep going until it is flush with the muzzle. If you are using the metal tack hammer, STOP using it before you hit the barrel itself. I have switched to using a large brass punch to carefully finish off the last few millimeters of the sinker going into the barrel. (as shown in Figures 5, 6, and 7)

Figure 5. Liberally grease around the lead sinker to help it go down the barrel. Lightly oiling inside the barrel will help also.

Figure 6. Starting the lead sinker. Try to start it out straight. Note the grease around the base.

Figure 7. The sinker is nearly all the way into the barrel. Note the shaving of lead at the muzzle. Seeing this assures that we have a snug fit. From this point on, use small cut sections of wood down to move the slug down the barrel.

A small ring of lead shearing off is what we want to see. This tells us it is going tight into the barrel. Take a short piece of dowel rod and use it to drive the lead sinker until it hits the long dowel. Tap it hard until it has fully set into the grooves of the barrel. Open and remove the bolt and remove the long dowel. If it sticks a bit tap the short dowel and the long one should slide out. Using the short sections of dowel, gradually tap the lead slug through the length of the barrel, adding another dowel section as you get near the muzzle. Eventually, the slug will drop out of the chamber and (hopefully) be caught on your soft towel (as shown in Figure 8).

Figure 8. Note the slug resting on the cloth. Also note the short sections of wood dowels.

Gently clean off the slug and examine it. You should see grooves and lands that correspond to the barrel�s rifling. Using your micrometer or caliper, you should measure land to land (that is ridge to ridge) to give the correct diameter of the barrel. If you measure groove to groove, this will be too small. With the correct diameter known, store the slug in something that will keep it from being damaged and write down the groove and land diameters, as well as rifle identification. You should only have to do this once, however, you could do it two or three times and make sure all measurements are repeatable. (Figure 9, 10, 11, 12)

Figure 9. An up close of the slug. Note the grooves in the slug.

Figure 10. Measured land to land, this is the widest of the slug. This would be the correct size bullet to use in the barrel. This is for the M95 Steyr rifle.

Figure 11. Slug measured groove to groove.

Figure 12. The slugs are stored in labeled gem stone padded containers.

Bullet Selection

If you desire to use jacketed bullets then log onto the various bullet makers sites and select a bullet, which matches exactly with your barrels groove diameter. In the case of the 6.5mm Carcano (actually .268�) Hornady has recently come out with specific jacketed bullets in exactly this diameter. Graf and Sons carries them.

However, let�s say your rifle has a odd size barrel, for which no bullet is made, or the barrel has seen considerable use and is worn a bit larger then nominal. Suppose your rifle is a black powder only rifle, which requires lead bullets? The answer is cast bullets. Many companies sell pre-cast bullets in various diameters and weights. You may need to get a bullet sizing set up to correctly size a cast bullet to the actual size you want. An example would be that you buy .338� bullets and size them down (and lube them) to .329� for the M95 Steyr. Some companies provide correctly size/lubed bullets in all sorts of diameters, not requiring any additional sizing.

A second choice would be to take up a little side hobby and cast your own bullets. Lee Precision has economical equipment which allows you to cast excellent bullets (see recent casting articles on this website).

In addition, Lee has recently added a universal flare die to their line up. When seating a cast bullet it is necessary to gently flare the case mouth or lead will be shaved. It comes with interchangeable plugs; so, one die can be used for all calibers. The plugs have a �floating� feature, which allows the plug to self-center in the case mouth. Other companies make flare dies, however they are caliber specific; one is required for each family of bore sizes, and they are rigid.

Using the procedures we have outlined here anyone can learn in a few minutes if they are using the correct size bullets for their individual barrel. Great increases in accuracy can result from this simple, inexpensive process.