January 04, 2011
By Wayne van Zwoll
A little extra work at the bench brings better performance in the field.
By Wayne van Zwoll
Accurate handloads begin with the case. Weigh them first, culling those that are .5 grain on either side of the median weight. Case length should be uniform as well.
When you consider that time is money, factory-loaded ammo is less expensive than what you can load yourself. And the stuff you buy at the store was loaded by companies with modern machinery and decades of experience, so, yes, it's probably superior to what you could load at home.
However, because many shooters tend to be self-reliant--with a preference to roll their own--handloading remains a passion among those who will look at a given load and wonder what if. . .
Your only hope of handloading ammo that's superior to what you can get from the factory is to make your loads more uniform. Accuracy, after all, is just another name for repeatability. If all your components weigh the same, have the same dimensions and add exactly the same amount of powder--and you hold and trigger the rifle exactly the same way every time--your shots will land in exactly the same spot (assuming stable conditions and an accurate rifle). If that's the kind of accuracy you're seeking from your loads, here's a six-step program to help make it happen.
1. Start with cases from the same maker and preferably from the same lot. Buy 100 at a time so you can cull them really hard and still come up with enough cartridges to last you many hunting seasons. (Varmint shooters may want to buy bigger batches.)
Cull the batch by weighing each case. Assuming the brass you've purchased is of uniform density, differences in case weight reflect differences in powder capacity, and this can affect velocity and accuracy. Set aside hulls that are more than .5 grain over or under the mean. Using once-fired hulls from factory loads is okay, but deprime them and clean them in a tumbler before you start culling.
2. Check flash-hole diameter. Most centerfire rifle flash holes are punched .082 and can be checked with a No. 45 wire size drill bit as a gauge. (Some--like the PPCs, 6mm BR and .223 Rem. target cases--have .060 flash holes.) While you're at it, cull cases with visibly off-center flash holes.
Now make primer pockets uniform with a Sinclair tool designed for that purpose. You want uniform depth. The primer must "bottom" in the pocket to support the anvil firmly and at a uniform distance from the bolt. This allows the striker to hit with the same force each time. Proper depth for large-rifle primers is .128-inch to .132-inch. For small-rifle primers and small- and large-pistol primers, the depth should be .118-inch to .122-inch.
Don't fret about pocket diameter. Primer pockets swell as they're used in full-power loads, eventually becoming too big to hold primers securely. Removing brass from the pocket wall just shortens the life of the case.
3. Measure the cases, base to mouth. You shouldn't need to trim them if they're fresh or once-fired hulls. But if you see some variation, set your case trimmer to take .020-inch off the mouth of a case that's exactly the specified length for the cartridge. Run all the cases through the trimmer. Within practical limits, case length doesn't matter as long as all the cases are of the same length and all are short enough that the mouth does not contact the end of the chamber. If contact does occur, the bullet can collapse into the case--boosting pressures during bullet release and affecting accuracy. Cases stretch as they're used, and periodic trimming may be required.
4. Deburr the flash hole with a flash hole deburring tool inserted from the case mouth. A punched flash hole--the most prevalent type--is commonly ragged on the inside. The primer flame is affected by that rim of jagged metal, and so is ignition.
Neck turning makes the bullet grip uniform and helps center the bullet in the bore. The difference in performance will be noticeable.
You don't want to remove material from the web, just the excess brass protruding inside the case. A depth gauge, set on the case mouth, helps in this operation. It's important to set the depth properly to take just the burr and not cut into the web.
5. Deburr the case mouth inside and out with a deburring tool. A tapered lip eases bullet seating and chambering, and it helps ensure uniform neck tension from one cartridge to the next. Don't remove a lot of metal; a couple of twists may be enough.
6. Measure neck-wall thickness at four points around the perimeter of the neck. If differences amount to more than .0015 -inch between cases, separate the cases into groups; cases at the extreme of the measurement range should be culled.
Neck-wall variations may reflect case-wall variations, which can't be so easily gauged. A .0015-inch disparity in measurements of an individual case means you'll want to turn the outside of the neck to make the wall thickness uniform. Adjust the case-trimmer cutter until it barely contacts high spots on the neck as you spin the case. Rotate the case as you push it forward on the spud. Shaved spots appear bright. Then ease the blade incrementally closer to the spud so your next spinning of the case neck takes off a little more brass.
Consistent wall thickness ensures that the bullet is gripped with uniform tension around its circumference and then is released uniformly upon firing. This consistency also helps the case center itself in the chamber and collapse uniformly in the sizing die. Inside neck turning may be used to eliminate "donuts" and remove excess brass in necks thickened by case forming.
Cases should be lightly lubricated before you insert them in the sizing die. Lube the entire outside of the case body, and lube just inside the mouth to ease passage of the expander ball. Use too much lube and you'll dent the case, typically on the shoulder; use too little lube, and the case will stick.
The Rest of the Basics
Neck size only. Unless you have a tight chamber, do not screw the die body down onto the shell holder. Leave a space the thickness of a penny between the two when the ram is at the top of its stroke. Adjusted in this way, the die will squeeze down the neck but will not push the shoulder back or compress the case body. Brass will conform to your chamber after one firing, so unless you want to use the case in another rifle, there's no point in making it
smaller than it is when you extract it. All you need is neck compression so the expander ball can go to work, ensuring just the right inside diameter for proper bullet seating.
If you neck size only, you eliminate excessive "working" of the case that occurs with full-length sizing. Just as a paper clip will break after you repeatedly bend it back and forth, a cartridge case will fail if you subject it to repeated expansion (firing) followed by repeated compression (sizing).
Belted cartridges are notorious for separating in front of the web. This is not a design flaw. It happens because the headspace measurement for belted cases is taken from the bolt face to the front of the belt, not to a point on the shoulder--as it is for rimless cases. Hence, the chamber's bolt-to-shoulder length is not as critical as it is for rimless rounds, which headspace on the shoulder.
Case preparation includes lubing. Keep the pad clean, and lube lightly. Shoulder dents mean you've used too much.
Magnum chambers cut too generously don't produce signs of excessive headspace on the first firing, but the stretch caused by repeated firings and sizings can result in separations. Neck sizing is the cure, since it makes the cartridge headspace on the shoulder--regardless if it's a rimless or belted hull. The tighter case fit not only gives you longer case life but helps the cartridge center itself in the chamber for better accuracy.
Prime with a hand-priming tool. I've primed in the press, but the great leverage there doesn't give you the "feel" of the hand tool. Feel is important because you want the primer to bottom in the pocket firmly--without crushing the anvil legs. Don't handle primers with wet or oily fingers.
I use standard primers with most loads, magnum primers when powder charges climb above 70 grains. A magnum primer generates a hotter flame of longer duration for sure-fire ignition of big charges. It's a good choice even with more modest loads if you'll be hunting in very cold weather or if you're using powders that are particularly hard to ignite.
Weigh all powder charges. A good powder measure used with ball powder can throw very uniform charges, but you'll have more confidence in the load if you've weighed the fuel. If you're loading magnum cases with coarse-grained stick powder such as H4831, a scale avoids the powder-jamming problems that slow down powder measures and call accuracy into question. Both balance-beam and electronic scales can give you sufficient accuracy--down to .1 grain. Use a powder trickler to add the final grains with more control.
You'll try several powders and loads to get the one that shoots best. I like powders that fill the case to the shoulder. Slight compaction is fine during seating, but I prefer not to crush powder. Breaking the granules changes their burning properties. You can put a huge amount of pressure on both bullet and powder with that press handle.
Seating depth not only affects accuracy, it also bears on how well your handloads will function in the field.
As with cases, you're smart to buy as much powder as is practical from one lot. Burning characteristics can vary between lots; they also change with age.
Generally, I try to pick powders in the middle of the burn-rate range for the cartridge. And I like to load close to the maximum levels in handloading manuals. Those maximums, I've found, are generally conservative, with a margin of safety built in. Adjusting powder charges one or even two grains at a time makes sense for big rifle cases, but as you approach maximum, you may find smaller adjustments produce significant changes in pressure, velocity and accuracy.
Bullet choice depends on your application and is beyond the scope of this article. However, for hunting cartridges, I like bullets on the heavy side of medium, with pointed noses. Both flat-base and boattail bullets will give you plenty of reach. The boattail has a slight ballistic edge at extreme range but is more difficult to manufacture without flaw because there are more angles on the bullet base. Uniform bases are crucial to fine accuracy.
Install the seating die so there's at least the thickness of a nickel between it and the shell holder at the top of the ram's stroke. For the first cartridge, adjust the seating stem so the bullet is seated firmly in the neck but more shallowly than you intend for the final product. Fine-tune seating depth with that cartridge, pushing the bullet into the case in short increments until it's right.
I generally want bullets seated with the ogive (the radius of the bullet between shank and point) .1 inch clear of the lands. You may get the best accuracy with the bullet seated to touch the lands, but direct contact with the lands allows no "run-up." That is, pressure from the powder gas must overcome neck tension and begin to engrave the bullet with the rifling at the same time.
This combination of forces may push pressures too high. Also, in a box of ammo seated to touch the rifling, you may have one bul
let seated a shade too far out, or whose ogive puts it in firm contact with the rifling. Result: The cartridge may be hard to chamber or extract. That's no big problem on the range, but it's troublesome in the field.
A lot of clearance between ogive and rifling--produced either by a deeply seated bullet or a long throat--is generally not conducive to fine accuracy. However, because it gives you long bullet run-up, it eases pressure to the point that you can often load more aggressively and get a little more bullet speed.
How do you know how deeply to seat? First, the bullet tips must clear the magazine box. If the bullet you seated shallowly won't clear the box, screw the seating stem in until the cartridge is .1 inch longer than the inside of the box. Now, insert the cartridge in the chamber slowly, pushing the bolt gently until you can feel the bullet contact the lands. If there's no contact--and you can lock the bolt easily--remove the cartridge and seat the bullet .1 inch deeper to clear the magazine box.
Then start seating the rest of your bullets. You know they'll clear the lands by at least .1, and you know they'll fit the box. You don't know if there's .1, .2, .3 or .9 inch of throat in front of the ogive, but it doesn't matter because you can't seat the bullet farther out unless you get a longer box.
If the test bullet does contact the rifling before the bolt closes, you'll want to seat incrementally deeper by alternately moving the seating stem down a turn and chambering the round. When you can just close the bolt without resistance, turn the stem down .1 inch for a final seating, then use that setting for the rest of your ammo.
Commercially made bullet comparators enable you to measure from the bullet base or cartridge base to the ogive. Overall cartridge length (OAL) is often used as a standard measure for factory rounds and is adequate for handloaders who aren't interested in precision. But because bullet points can get banged up and may even differ slightly in shape when they're shipped, OAL isn't as useful a measure as is the length of a cartridge from base to ogive. The better tools feature bushings for various bullet diameters. They can also be used to check headspace.
Crimping has been criticized out of hand by shooters who have never tried it. It is one more operation and, thus, one more variable. For bottleneck centerfire cases that hold bullets securely, crimping may also be unnecessary. But it can actually improve accuracy as it boosts the pressure needed to pop the bullet free. The result can be a cleaner release and more uniform velocity. Factories routinely crimp cartridges, and some of this ammunition is one-hole accurate. Two points to remember: 1) Never crimp except into a crimping groove on the bullet; and 2) Crimp lightly to start!
Handloading is a simple procedure, but the more you put into it, the more you'll get back. You can equip yourself only with the essential equipment and kick back, or you can sink some money into specialized tools and adopt slightly more complicated loading methods that will make your ammo that much more accurate--more accurate, even, than factory loads.