FACTORS IN ACCURACY, cont'd
Forward of the chamber body we find the neck. This rarely causes problems, except in odd instances where brass is too thick to allow the bullet to release easily on firing. This almost never occurs with new brass, but thick necks can develop after brass has been fired and resized several times. Brass starts to flow forward, thickening the neck, particularly at the shoulder/neck junction. If the neck "grows" enough, chambering a round slightly crimps the neck around the bullet. This not only increases pressures, but does so erratically. The normal symptoms are unexplainable fliers and occasional signs of high pressure.
Check for this condition by inserting a bullet into the neck of fired, unsized brass. If there's any slight hitch, the brass either needs to be discarded or the neck turned. Bulk brass is cheap enough that I just toss cases in common calibers, but expensive brass (either off-the-shelf or in forming time) gets outside-turned.
Brass fired several times also tends to work-harden, the result of being stretched and resized. This particularly affects the neck, because it's sized twice, once when squeezed down, then again when pulled over the expander ball. Work-hardening also causes erratic bullet release. Again, I generally toss common calibers after a few loadings, but anneal more expensive brass.
The traditional annealing method suggests heating the necks "cherry-red" with a propane torch, then dousing in cold water. But cherry-red makes the necks too soft.
The melted-lead dip method is much better, as is Hornady's annealing kit, but I use a simpler method perfected by my friend Fred Barker. With Fred's method you hold the case in your fingertips, halfway up the case body, then heat the neck in the flame from a common wax candle, turning it constantly, until the case gets too hot to hold. Drop it onto a water-soaked towel, then use the towel to wipe the case off, which finishes the annealing and gets rid of the black soot from the candle. The Barker Method is fast, cheap, easy, and anneals just the right amount.
The next part of the chamber is the throat, or leade, where the rifling begins. Most factory throats are cut far larger than bullet diameter, at least at the mouth of the case, the reason many handloading gurus advise seating bullets as close to the lands as possible. Close seating doesn't allow the bullet to turn slightly sideways in the throat before slamming into the rifling.
However, most custom chambers (and even some of today's factory rifles) have throats only slightly larger than bullet diameter. With these, seating the bullet close to the lands really isn't necessary, except perhaps with light varmint bullets that have very short bearing surfaces.
A good example of a precise custom throat is the one in the .300 Winchester Magnum Charlie Sisk (400 County Road 2340, Dayton, TX 77532, 936-258-4984) just built me on an old-model Ruger 77 action (chosen over the 77 Mark II because of the tang safety and better trigger). This rifle has a ".30-06 length" magazine that only allows bullets to be seated out to the standard .300 Winchester overall cartridge length of 3.34". I mean this quite literally; I've tried seating bullets to 3.35" and they jam in the magazine. The throat, however, allows Nosler Partitions to be seated out to an overall length of nearly 3.5". In theory accuracy should suffer, but because of the tight cylindrical throat all the handloads I've tried so far grouped under an inch at 100 yards.
The throat of the .300 Winchester Short Magnum (and the other WSM's) is interesting, mostly because it doesn't exist. The rifling starts right in front of the chamber's neck, which not only keeps overall length of cartridges short enough to fit in a 3.05" magazine, but eliminates any worry about inaccuracy resulting from "bullet jump." This non-existent throat is one reason factory-model WSM's of any caliber tend to shoot very well. (It's also why chambering a WSM in a longer action is mostly a waste of time. A local gunsmith has already built several .300 WSM's on Mauser and other longer-magazine actions, because the boys want to "seat the bullet out to the lands." But they won't be able to seat bullets out any farther, because the non-throat won't let 'em. If you want to use a longer action, why not use the .300 Winchester "Long?" It achieves the same ballistics, or slightly better, and despite what you've read, doesn't kick any harder than the .300 WSM.)
The next step is the case itself. Over the years much advice about "uniforming" cases has been printed. I've tried it all, from reaming primer pockets to weighing cases to removing the little burr on the inside of the flash-hole. All these details may have some slight effect on benchrest ammo, fired in rifles capable of one-hole groups, but even some benchrest boys have given up on most of 'em.
Why? They don't make any difference. The only case dimension that seems to help shrink groups is uniform neck thickness. Ideally, necks shouldn't vary more than .001" in thickness. Before measuring, most bulk brass must be run over an expander ball to remove dents. Otherwise you'll be measuring dents, not brass.
All of this takes time, but you only have to do it once. I buy most of my brass from Midway USA (5875 Van Horn Tavern Road, Columbia, MO 65203) in 100-500 round lots, and sort necks on any batch from Remington or Winchester. The reject rate usually runs between 5-20%, and you can use the rejects for offhand practice or dummy rounds--or neck-turn them to the same uniformity as the "good" cases.
I used to turn necks, but no more. As a general rule brass with bad necks is lopsided all the way down through the body. It may be straight after it's fired, but won't be after full-length sizing.
I don't bother weighing brass anymore, either. Most of it's just too uniform these days. The first time I've weighed brass in a couple years was yesterday, just for this article. The only batch that varied more than 2% was some Winchester .300 Savage brass, at 4.8% still only plus or minus 2.4%, which matters not at all in the real world. I use the same brass for handloads in both of my Savage 99's, one peep-sighted, the other scoped. The peep-sighted rifle (a takedown) will average a little over 1" for 3 shots at 100 yards, the scoped rifle under .75".
Here are some other weighing results from recent bulk brass:
.223 Rem. (Rem. brass): 1.1%
.250 Savage (Win.): .09%
.257 Roberts (Rem.): 1.2%
.30-40 Krag (Rem.): 1.1%
.300 H&H (Win. brass), 2%.
This is plain old everyday brass, the same that's used in Remington and Winchester factory ammo, and fired Federal factory brass varies about the same. Federal Gold Medal, Lapua or Norma brass varies even less, usually less than .05%, and you also don't have to bother checking their neck thickness either. I still do occasionally, though why I don't know, since it always measures .001" or less.
I don't deburr or "uniform" flash-holes anymore, and very rarely ream primer pockets to uniform depth. Most primer pockets these days are extremely uniform, varying much less than average "depth" of primers themselves, even match-grade primers.
But just to find out how much effect everything except uniform necks has on practical accuracy, I performed a experiment last summer. My most accurate rifle is a Remington 700 in .223 Remington, with a heavy chrome-moly barrel and laminated stock. Aside from minor tuning, it's out of the box. With the right load it's a genuine quarter-inch rifle. (Hell, it may be better than that, but I'm not.)
The experiment involved 40 rounds of experimental ammo. All the brass was once-fired Winchester, shot in the same rifle on a recent prairie-dog shoot.
Twenty of the cases were perfectly matched. They weighed within .2 grain of each other, had their primer pockets and flash-holes uniformed and deburred, and were selected for necks within .001" uniformity.
The other 20 cases were only selected for .001" necks. They weren't weighed, and their primer pockets and flash-holes were left as-is.
All 40 cases were resized and decapped in a Redding Competition Bushing-Style neck die. Then their necks were trimmed in an RCBS bench tool, then carefully deburred so there wasn't any ridge either inside or outside. Primers were CCI 400 Match, seated using an RCBS hand tool. Then 26 grains of Ramshot TAC was measured into each case, and 50-grain Nosler Ballistic Tips seated.
I waited for a very calm day to shoot. The barrel was cleaned to bare steel beforehand with JB Compound, and I fired 2 fouling shots with Winchester factory ammo before testing. I started with the "uniformed" loads, shooting a 5-round group, aiming with a 6-24x Bausch & Lomb Elite 4200, set on 24x and adjusted to eliminate all visible parallax at 100 yards. After letting the barrel cool, I shot a 5-shot group with the random brass, then let the barrel cool again. Groups were alternated between the uniformed and random brass until all 40 rounds were gone.
The results? The entire average was right around .25", the smallest group just under .2", the largest just over .3". The average difference between the two "lots" was a few thousandths of an inch--in favor of the random brass. Now, maybe if I shot 100 groups the uniformed brass might have done better. And maybe not.
Such results are admittedly unusual, and almost solely due to the most important factor in accurate handloads: the bullet. The Ballistic Tips had all been run over one of Verne Juenke's Internal Concentricity Comparators. About 1 in 5 tested perfectly enough for my experiment; 5-shot groups fired randomly selected bullets from the same box average between .5" and .75" with the same load. But "perfect" Ballistic Tips shoot better than any other bullet I've tried in this rifle, even benchrest bullets that have also been run through the Juenke machine. I cannot emphasize how much this machine has changed the way many shooters look at accuracy. Before using the Juenke machine extensively, I believed that certain rifles "liked" certain bullets better. Like most shooters, I'd try different powders in order to get a desired bullet to shoot better--and sometimes even a different primer. This didn't work very often. Now I know why. Without good bullets, uniform neck thickness and consistent ignition all the rest of it doesn't amount to a pile of popcorn.
Today finding an accurate load is much simpler. I carefully resize some neck-sorted, fired cases, charge 'em with an appropriate powder or two, then seat some Juenked bullets and go to the range. If the rifle's set up correctly, almost every load shoots acceptably.
Sure, different powder charges can result in smaller groups, and very occasionally a powder just doesn't agree with a certain bullet. One recent .300 H&H loathed IMR4350 with 180-grain bullets, and one batch of .22 Hornet cases needed their primer-pockets reamed. But 85% of the time, I find an accurate load on the first try, without all the nit-picky stuff we've been led to believe makes a difference.
Of course, very few of us own Juenke machines. I believe the existing total is around 500--but they're already making a difference in the bullets we shoot. Swift's Sciroccos are made with a Juenke machine, and match-grade bullets from other companies get spot-checked over them too. I'm guessing they'll be used in the manufacture of more bullets in the near future.
One thing I've found through the use of the machine is the fatter the bullet, the less difference small manufacturing variations make. It's a lot easier, for instance, to make a concentric .30 caliber bullet than a balanced .25 caliber bullet, one of the reasons many .30 caliber cartridges have a reputation for accuracy. But the most consistently concentric bullets are those of .35 caliber and up. In fact, I rarely test any bullets of .35 caliber or more that don't check out essentially match-grade. Which is why so many .375's and .416's shoot little tiny groups--if their owners can take the recoil.
But even if my Juenke machine disappeared tomorrow I'd waste less time in my handloading. Trying a half-dozen powders in hope of getting a certain bullet to group, reaming primer pockets, weighing brass--all those things have become obsolete around my loading bench, because accurate handloads mostly boil down to starting a good bullet straight down the barrel.