Shooting Technique:
Consistency is everything: After all the thousands of rounds I fired in the warehouse, I developed a technique that was practically infallible. I did exactly the same thing every shot. I was like a machine, and once you find out what works, you don’t change anything. I tried to put my fingerprint on the trigger exactly where my last fingerprint was. Consistency is everything.
Shoot free recoil: We discovered that if you want a gun to really shoot, you can’t cheek it, you can’t shoulder it, you can’t hand it, you can’t thumb it. The only thing you touch is the trigger. I didn’t even touch the bench. I planted my feet solidly on the floor and kept them right there. Your shoulder should be 3/16″ to 5/16″ from the stock so you can catch the rifle immediately when it recoils back, otherwise the rifle will get back too far and disturb the rear bag.
Rear Bag: The rear bag and the way you manage it is crucial. First, he positioned the rifle on the bench so the stock barely protruded from the “V” of a rabbit-ear bag, then he pounded the stock firmly into the bag. As already mentioned, when the rifle recoils, it’s important that the bag stay put. With proper bag technique, when the rifle is returned to its firing position, any sight corrections should be slight and made by tiny manipulation of the rear bag. The less bag adjustment, the better. The rear bag was packed very firm with casting sand, which is about 33% heavier than common sand. He then applied water and formed the “V” to the rifle stock by pounding the stock into the bag and allowing the leather to dry. Done only once, this step hardens the leather and makes the stock slide smoother. A mixture of equal amounts of talcum powder and white graphite applied to the back and front bags provided smooth sliding of the rifle, even in very humid conditions.
Front Bag & Fore-End Stop: He packed the front bag as hard as iron. Here he employed a one-to-three mixture of Portland cement and casting sand. The cement doesn’t set, but it does help hold the bag shape by resisting the twisting force imparted to the fore-end by bullet torque. No side support was used for the front bag. He strongly advocates the pedestal fore-end stop. He adjusted the stop so the front bag supported the fore-end about halfway from the end of the fore-end to the receiver. He said if the bag is positioned farther forward, this part of the stock is too springy, and accuracy will suffer. When resetting the rifle after firing, he bumped the fore-end stop and then pulled the rifle back “one-millionth of an inch.” Contact between the stop and stock tended to deteriorate accuracy.
Cleaning: Barrels were cleaned every six shots (one 5 shot group plus a fouler). They found they were able to predict where every bullet would print shot-to-shot, but that only applied if the rifle was cleaned between groups. He used a bronze brush and solvent each time, and at regular intervals the barrel had to undergo a scrubbing with J-B compound to remove solvent-resistant fouling 3″ to 4″ up from the chamber.
Reloading & Components:
One thing he stressed is that bullets must be precisely seated against the lands. He NEVER fired a single official screamer group when he was “jumping” bullets. All his best groups were always seated into the lands, or at the very least touching the lands. His practice was to seat the bullets so the engraving was half as long as the width of the lands.
Case Prep: He thought “tuning” a case was one of the most critical pieces of small groups, and that goes far beyond sorting, neck turning and prepping the primer pockets and flash holes. Here was his full process for case prep:
Weight sort cases
Anneal the necks with a small propane torch
Fire-form cases (from 220 Russian to 22 PPC) by loading Bullseye powder behind toilet paper bullets and fired the rounds in a special rifle assembled for this purpose
Inside bore the case necks on precision lathe with the necks supported in a die
Outside turn the necks for a total clearance of .0007″ between loaded round and chamber. Since his neck turner left cutting rings, he sanded the necks shiny smooth, which typically resulted in a somewhat widened neck-to-chamber clearance of .00075″.
Flash holes were cut identically and chamfered inside.
Then, this step could be the most critical – the “tuning” step requiring a sensitive touch and #400 sandpaper. The secret is to get the neck tension (the grip of the brass on the bullet) exactly the same on every case. You do this by firing the case and then feeling the bullet slide in the case neck as you seat it. Here, a micrometer won’t do you any good. Feel is the whole thing. If any case grips the bullet harder than the others, you take three turns over the sandpaper and fire it again, until you get exactly the same amount of seating pressure.
After a case has been fired a couple of times, he pressed a tiny groove pressed into the neck with the pressure ring. This will cause a flat-base bullet to “snap” into place when it’s seated. He thought feeling the bullet slide down the neck and then snap into place told him everything he needed to know about whether that round was going to go into the group or not.
He would use cases 20-25 times before a case would no longer grip to his satisfaction.
You can change the powder charge slightly, and it won’t really make any difference, but if you change the bullet seating depth or the grip on the bullet, you’re going to see bad things happen fast.
To get a good sense of bullet seating pressure, Virgil seated bullets in a Wilson straight-line tool BY HAND — not arbor press. He estimated that the seating pressure on his hand was moderate — perhaps 15 pounds. If seating requires significantly more pressure, the operation damages the bullet’s fragile pressure ring, bulging your groups. If the seating pressure is too light, he said you’re assured a mediocre .250″ rifle.
He never used chronographs. As long as the bullet went in the same hole as the previous one, it didn’t make any difference how fast it was traveling.
Myths Busted:
Powder charges, as long as they were fairly consistent and bracketed within a couple of grains, were not important. He threw all of his charges with a Belding & Mull powder measure, and for one experiment he shot groups using three different powder measure settings (51, 52 & 53) … all three groups were identical.
Lot variation in powder didn’t seem to have any effect on accuracy, even on when using IMR 4198, which has a reputation for varying considerably from lot to lot. He would just buy powder as he needed instead of laying in a big supply, because he found no evidence to support that powder lot variance affected accuracy in the least.
He never saw an inaccurate primer, and was unable to detect any accuracy variances resulting from seating pressure.
Rumors have persisted for years that some rifles shoot proportionally better at 200 yards than 100 yards, or vice versa. Virgil files that one under “occultism.” His experience in the warehouse was, if a rifle was shooting a consistent .100″ at 100 yards, it shot a consistent .200″ at 200 yards.
He did NOT uniform primer pockets or turn the case bases. He also did NOT size his case necks.
вот отсюда
http://precisionrifleblog.com/2013/10/18/secrets-of-the-houston-warehouse-lessons-in-extreme-rifle-accuracy/
там же лежит полный вариант статьи в pdf
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