Precision Rifle Blog posted up this article about a Houston Warehouse that was used to achieve the impossible in precision shooting. There is a warehouse in Houston that was used as the ideal indoor shooting range by precision shooters. It was one of those places that you had to know someone and that someone had to like you for you to get in. That person was Virgil King. Dave Scott interviews Virgil King, the man behind the warehouse. According to the article, they were able to achieve 5 shot groups in the “zeroes”.
The most accurate rifle ever to punctuate the stillness of the Houston Warehouse happened to be Virgil King’s own 10 1/2 pound Light Varmint benchrest rifle. The rifle was built around an action made to Virgil’s specifications by Houston shooter Wilbur Cooper, a mechanical engineer, master machinist, and fanatical perfectionist. The action was machined from #416 stainless steel and had an integral sleeve extending 5/8″ forward around the barrel, but not touching it, to provide additional bedding surface. Virgil said the tolerances were held so close in this action that he estimated, as an example, that the clearance between the bolt and boltway measured perhaps a minuscule .0001″ on all sides. Consequently, simply inserting the bolt took a measure of concentration.
If the rifle looked like the devil, it shot like the hammers of hell. “Day after day, weekafter week,” Virgil recalled “it would NOT shoot a group in the warehouse bigger than.070″. You had to cheek it or thumb it to get it to shoot that big. Generally, it shot.035″ to .050″, with most groups holding around .035″. But now and then you’d sneakone in a little better than that.”
Powder charges, as long as they were fairly consistent and bracketed within a couple ofgrains, were not important, he said. On one occasion, as an experiment Virgil shot onegroup with his 6PPC barrel on the Cooper action using a 53 Culver setting of Winchester748, the next 52 and the third 51. All three groups were identical.
Building a load is important, Virgil conceded, but “tuning” cases is what stands between you and that final fraction of an inch that separates a good gun from a barn burner. “Tuning” cases goes far beyond sorting, neck turning and prepping the primer pockets and flash holes. These case refinements will get you only so far, Virgil stressed. To produce cases capable of shooting groups better than the guy at the next bench, you have to go the extra mile. And you make the journey with sensitive hands and a piece of #400 sandpaper. For Virgil, the process started by purchasing a substantial number of Sako .220 Russian cases. (Yes, Virginia, there once was such a case.) After the cases were weight sorted, he annealed the necks with a small propane torch. He then loaded Bullseye powder behind toilet paper bullets and fired the rounds in a special rifle assembled for this purpose. The necks of the fire-formed cases were next inside bored. This was accomplished on a precision lathe, with the necks supported in a die during the operation. Virgil would then outside turn the necks for a total clearance of about .0007″ between loaded round and chamber. Since the neck turner left cutting rings, Virgil sanded the necks shiny smooth, which typically resulted in a somewhat widened neck-
to -chamber clearance of .00075″. He emphasized that until the hills and valleys were smoothed, the case neck was prevented from laying flat against the chamber. Flash holes were cut identically and chamfered inside, but he didn’t uniform primer pockets or turn the case bases. He also had not the foggiest idea what amount of case-wall variances existed in any of his brass, but in those excellent Sako cases, probably not much. Then came the final, critical step. The step requiring a sensitive touch and #400 sandpaper — the “tuning” step. “The secret,” Virgil said, “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. Until the necks were tuned, I didn’t feel I was ready to start tuning the gun.”
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 admitted, however, that his knowledge here is limited, because in the warehouse they rarely fired at 200 and 300 yards.
There is a lot of information in this article. A lot more than this novice shooter can comprehend. However the last secret that Virgil dangled to Dave Scott was that he was able arc his 22PC to get consistent 0.025″ groups!!
To read the whole article click here.