Handloading for Accuracy

1994
By Dave Reed and Mark J. Miller

Introduction

Hand loading is the only way you will find the best load for your rifle. If you are very good at it, you will be able to make ammunition that is superior to factory loads. It is not accurate powder weighing that gets the job done; factory machines are pretty good at that. The secrets to superior handloading are: case selection/ preparation; overall length; and bullet runout.

Factory cases can vary a good bit in wall thickness, volume, and are sized to fit the standard specifications for rifle chambers of the particular cartridge. They are "one size fits all." There is no magic process to cut chambers. They are reamed with tooling that gets a little duller with each pass. Spindle vibration and the metallurgy of the tooling and the barrel are also factors that make each chamber unique.

As I discussed in "Rifle Tuning", the distance that a bullet "floats" before it hits the rifling in the bore is critical. Some rifles are cut with a throat so long that it is impossible to make your round long enough for the ogive of the bullet to get close to the lands. If the throat is not too long, we can adjust the length of our loaded round so that the ogive sits .003" - .005" from the lands of the rifling. Factory bullets will not be anywhere near this close.

If a bullet is not pointed straight down the bore it will be 'cockeyed' when it comes out the muzzle. The 'straightness' of a bullet is called runout. If your bullets are all canted in random fashion (even though you can't see it with the naked eye), they will come out the muzzle in a random fashion and your shot groups will suffer. If you are familiar with cryogenics, or any of the numerous magazine articles about the Browning BOSS system, then you know something about barrel harmonics. It is possible to adjust harmonics for each bullet you shoot. In theory, any weight bullet can be made to group well, though for long range shooting you will probably be working with a pointed boat tail bullet. Handloaders should sample bullets from many manufacturers and select the one that shoots best in their rifles.

Introduction, Record Keeping, Brass, Primers, Bullets, Powder



Brass

Brass varies from lot to lot. For all handloading components you should follow this rule: When you buy, buy a lot. When you get a good run of the product you'll have plenty. It also helps with consistency. Brass from the same lot has shared characteristics.

The first time you fire your brass it will form to the dimensions of your chamber. This is called fire forming. Many handloaders will not use once-fired brass from another gun for this reason.

When you look at the mouth of a rifle case the brass looks pretty thin. If you cut one in half, you will find that it gets pretty thick towards the base. In the factory, brass cartridges are punched in a die. This makes it thicker at the back. You need the strength afforded by this thickness. Thin brass will cause significant problems. For example, .300 Winchester Magnum brass is usually good for 3 - 5 firings. Moreover, I have bought factory ammunition, fired it, and discovered signs of case head separation after the first firing. I had no choice but to discard it. Case head separation is where the case begins to split around its circumference near the base of the cartridge, because of thin or brittle brass. A telltale sign of imminent separation is a shiny ring around the cartridge near the base. A good method to measure the thickness of the case is to use a special dial micrometer setup. You start at the base and slide the case between the inner prong on the device and the dial mic on the outside. If the case is starting to separate, you will see a sudden drop in the thickness at this point. When the thickness drops more than .01 - .02 you may have cause for concern.

When a round is fired, the brass flows or moves out against the chamber wall and forward. (It can't go back). If cases are not trimmed properly, it is possible for them to become long enough that they contact the lands on the next shot. This is an extreme case (pun intended) but it can happen, and it is very dangerous. With the same case thickness tool, you can also measure the uniformity of the brass wall thickness. Since one side of the case is thicker than the other, the thin side will stretch more than the thick side. This uneven movement of the brass is as bad as (or worse than) having bad lug fit-up or an uneven bolt face. The bullet will be launched unevenly. By spinning your cases you can find the ones that are the most uniform and separate these cases from the rest. You should look for cases that have no more than .001 thickness difference from side to side. Once you have determined which side of the case is the thin side, make a mark with a scribe on the base of the case where the headstamp is. This side must get maximum support in lockup. We do this by aligning the thin side with one of the locking lugs in the rifle. This is called indexing the case.

Case weight also varies. The wall thickness measurement only tells us how uniform the wall is. Since thicker walls mean less case capacity, variations in volume will cause minor differences in pressure when the round is fired. This is important if you are trying to put 5 shots through the same hole in a benchrest match. For practical purposes I wouldn't worry too much about this measurement. Minor pressure differences have very little effect on consistency. As we shall see later, it is not necessary to weigh powder on a laboratory grade enclosed scale. The other components are far more important. If you want to, you may want to try weighing a few cases to see how much variation you have. If you have 3 percent of the cases that are much lighter or much heavier than all of the rest, you may want to discard these. We think that the time would be better spent doing other things.

All major brass makers make good brass. The trick is to find a good lot and buy a bunch of it. I (Dave Reed - ed.) like Winchester. But I really use it because Midway and Graf & Sons usually have it for a good price. There are a lot of other things we are going to do with our brass, so read on.

Introduction, Record Keeping, Brass, Primers, Bullets, Powder



Primers

Primers are very dangerous items. If you want to try a test to see just how powerful they are you might want to try this one. (I'm assuming you already know basic handloading at this point, if you don't, don't try this until you have a firm understanding of all basic principles.) Load a brass case with a new primer. Don't put in any powder or a bullet. Take it OUTSIDE in a safe area. DON'T point it at anyone or anything you do not want to destroy! Fire the case in the gun. The flash and noise from the primer alone will surprise you. I read an article once about a guy that had one go off in his press during handloading. I don't remember what he was doing; he may have run a live primer through his resizing die with the decapping tool in place while standing over the press. Anyway, a small piece of the primer went all the way through his chest and into his lung. He wasn't sure how bad it was but went to the doctor anyway (SMART). The X-rays showed the piece in his lung. He was in the hospital for about 3 weeks. Think what would have happened if it had gone into his heart or an eye!

OK, enough of that, if you already know how to handload then you know to always wear safety glasses when handloading. If you are one of those types that think these things only happen to idiots or the other guy, then handloading is definitely not for you. (If you have not handloaded before then please don't assume that I'm giving you all of the things you need to know here. This information is for people who already know basic handloading and have already read all of the safety stuff.)

Primers are very resistant to the natural oil on your skin. You can handle them safely. My favorite primer is RWS. You will have to decide for yourself. All of the major brand primers are good ones. I just seem to have better results from RWS than from the others. There are large rifle, small rifle, and large rifle magnum primers. It is not unacceptable to use large rifle primers in lieu of magnums in a magnum rifle. The magnum primers are hotter and put out a bigger flame than the regular type. They are designed to ignite larger powder charges. (Importantly if you change primers, remember to start at a minimum charge and work your way back up).

We will discuss primer-seating methods later, read on.

Introduction, Record Keeping, Brass, Primers, Bullets, Powder



Bullets

What are you going to use the bullet for? How fast will it be moving when it hits the target? Hollow points expand easier than other bullet shapes. Round nose bullets expand well and seem to retain weight better than others. Full metal jackets don't expand as easily as others do. Boat tail bullets offer better stability at extreme ranges. Flat-based pointed bullets fly well to around 300 yards. The bullet shape you use really depends on how well it shoots in your rifle, and at the range and velocity you are trying to achieve. Serious target shooters rely on hand swaged bullets for accuracy. People make these bullets at home using the finest materials.

If your washing machine goes into the spin cycle with a lot of heavier clothing on one side of the tub what happens? At high speeds the washer will shake and vibrate like it is going to come apart. What would happen to a spinning bullet if one side of the bullet were heavier than the other side? The same thing, of course, and your groups would suffer. The jacket material is actually a thin piece of copper tube. If the inner diameter and the outer diameter of the tube are concentric, then the jacket won't cause the bullet to be heavier on one side than another. Next comes the filler, or the core. This core is swaged into the tube and the whole thing is formed into a bullet shape. Most of the handmade bullets I've heard of have been in .22 caliber and 6mm.

Someone probably makes them in .30 cal. but I don't know who it is. Up until the last couple of years, most serious shooters were buying their bullets from one or two guys (I can't think of their names). Mark Miller adds the following names of companies that make hand swaged .308 bullets -- Council, Chism [very popular in hunter class bench rest], Euber, Locklin, SG. Also, Mark recommends Lapua (isn't made by hand, but makes a good showing in service and Palma matches). For my purposes factory bullets are good enough.

How heavy a bullet should you use? Heavier bullets require a quicker twist to stabilize them. 150 grains is the lightest you should use in a .300 Winchester Magnum. 165 to 168 grains are a good size for long range shooting in the .300 Winchester Magnum. 180-grain bullets might be a good choice for the Imperial or other hot .300 magnums.

All 165-grain bullets will not yield the same pressures when loaded identically! If you have worked up a pretty hot load do not assume that it will be safe when you change to another bullet of the same weight. I did this once (violated the cardinal rule of starting over when any component change is made) and got dangerously high pressures. They were high enough to flatten my primers. I thought the recoil/jar felt different and did not notice it until I'd fired about 5 rounds. I had twenty rounds loaded and had to destroy them all. (BTW -- Maybe I'm just incompetent but I have had no luck with kinetic bullet pullers. Copious amounts of powder go everywhere and I'm left with a case with nicked mouth and who knows how much powder clinging to the insides. I just pull the bullets and squeeze the case in a pair of pliers -- with the mouth pointing away from me, and discard, the loss of the case isn't worth the hassle to me. If you were in a situation where every case really counted I guess it would be different.)

Introduction, Record Keeping, Brass, Primers, Bullets, Powder



Powder

Keep your powder dry and cool. Do not expose to heat or light. Kept properly, it will last almost forever. Never mix powders. Don't try to experiment by mixing one with another to try and achieve a 'happy medium'. I've never tried it but, according to others, the burning rate will be unpredictable. I don't know why this is so . I just follow the rules. As with brass, buy your powder in the biggest cans you can afford, preferably more than one keg at a time.

There are lot-to-lot differences in all powders that will cause inconsistencies. When you have done exhaustive testing of brass, bullets, and primers with one powder, that's usually the time to buy more. You don't have to start over again, but you do need to reduce the load you worked up and gradually work back up until you find the right combination. Generally, slower burning powders are necessary to get the pressure up to where it needs to be for a large magnum rifle. Be careful about reducing the load for the .300 Winchester Magnum. It can do strange things (high pressures) if you get too close to the minimum load recommended. I always start with an amount close to, but above, minimum (usually the next higher load in the books). 4350 is a very versatile powder for high powered rifles. It can be used for every thing from a 22-250 all the way up to .338 Win Mag with very good results. IMO, 4350 works better for me than 4831. It will work well with regular large rifle primers in many calibers. I have never gotten 4831 in the right combination with any of my .300's. I don't travel in exclusive target shooting circles though; maybe some of those folks know how to do it.

Introduction, Record Keeping, Brass, Primers, Bullets, Powder



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