Squeeze more accuracy: improving your handload's quality is time consuming but rewarding.
The makeup of a load--what I call the "recipe"--is the primary factor in accuracy and overall round performance (which includes good velocity and behavioral consistency). No doubt, there are propellant and bullet combinations that, along with the right mix of other components, produce high, consistent velocities and reliably small shot groups. It's necessary to make some assumptions because we're taking a general topic (accuracy) and narrowing it down, and one assumption now is our combination has been found. Right, you have "The Load." Now we can talk about improving cartridge construction and evaluation criteria with the goal of maximizing accuracy.
The most any of us can hope for is to have each shot go right where the sight was when the shot broke. We may not always have the sight exactly where it should have been, and environmental conditions sometimes aren't corrected for as they should have been, but if we reduce the influence of ammunition as a variable then we've narrowed the "blame" for a shot away from target center.
Gunwriters, shooters, all of us, talk about "flyers." That's when one round--or more--lands outside the usual group. Eliminating the shooter and rifle as overt contributors to a wild shot, a flyerresults from a cartridge-quality issue. Maybe the bullet wasn't seated in accordance with the majority of rounds in that box. Maybe the case neck was holding it off center. Maybe there was a little more or less propellant. Maybe the primer wasn't fully seated. And, yes, it could be a combination of factors as well as a single thing.
There's much written about lab-grade handloading practices from Benchrest competition. We can't obtain the level of perfection Benchrest shooters achieve for several reasons. Mostly, our rifles have to function. A Benchrest rifle's chamber/loaded-round combination is so close they normally don't so much as resize a case neck. These folks often show up at an event with five cases, which are used and reused for the duration of the day. They're perfect little cases, to be sure. Outrageously unrealistic. The good news is applying a few tricks and insights to "standard" handloading practices can improve loaded-round quality.
The start is a combination of the sizing and seating dies choice, and then more of it is in how those are set up into the press.
Propellant charge consistency factors strongly. As with many things, this influence varies with the level of deviation.
If ammunition starts off "straighter," it should very well shoot "straighter." Or that's the logic and belief behind the efforts some handloaders make to attain better concentricity in their loaded rounds.
Concentricity, essentially, is the quality of the relationships among various circles that are a part of a cartridge. Ideally, all circular objects should share a common center. That's the bullet, the case neck, and the case body, and, ultimately, the barrel bore.
To attain measurably "perfect" concentricity (which, to me, is less than 0.001-inch runout), the case neck walls have to be consistent thickness all around the periphery. That's not going to happen unless we make it happen. Even the very best (most expensive, at least) cases don't exhibit such perfection. Outside case neck turning is the only way to perfect case neck wall imperfections. It's tedious. I'll assume we're not going to do it. So, the most we can do is ensure none of our tools are contributing to runout. The accuracy tips in yonder sidebar are 6 steps to achieve this.
The preceding was a specially adapted excerpt from the book Top-Grade Ammo coming soon from Zediker Publishing. See ZedikerPublishing.com or BuyZedikerBooks.com to order.
Forster Products, 310 East Lanark Avenue, Lanark, IL 61046, (815) 493-6360, www.gunsmagazine.com/index
6 DIE "ACCURACY" TIPS
Select a few cases from your stock that exhibit the measurably most consistent case neck walls for tips 3 and 6. If you don't have an inside-micrometer, just do your best with a caliper to measure the case neck wall thickness at 4 points around the case mouth.
1. Remove the spring clip from the shell holder socket on the press ram. Use an O-ring in its place to retain the shell holder in its slot. The clips cock a shell-holder at an angle. Keep the shell holder undersides clean and lubed.
2. Polish the expander in your sizing die. It's usually possible to chuck its stem in a drill and spin the contact surface against emery paper. I use 600-grit. This helps a lot. With 600-grit there should be no measurable reduction of the expander diameter, but even if there is a little it won't hurt a thing.
3. Take time to align the expander. Loosen the locking nut on the expander/decapping stem. Size a case you know has uniform neck walls and, when the case is just being withdrawn (you'll feel it engage the expander), tighten the locking nut on the stem.
4. Placing an O-ring under the locking ring on your sizing die lets the die float a little to better align. If you do this, dab a paint mark for an index reference between the die and the press to know it's installed and adjusted right where it should be. Works well on conventional seating dies also.
5. Upgrade your bullet-seating die. Those incorporating a sleeve that houses the case fully before being run up to engage the bullet-seating stem are way on better. That way, everything is held in alignment prior to the bullet entering the case neck. If not, follow the same process as suggested to align the expander: loosen the seating stem, seat a bullet, and, holding the works captive, tighten the stem-locking nut.
6. Make certain the bullet seating stem is engaging the bullet at some point along its nosecone area, not just at the tip. Remove the stem and check. Get it to a machinist if necessary. This makes a huge difference.
Photos: Yvonne Venturino
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|Title Annotation:||UP ON ARs|
|Date:||May 1, 2016|
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