I posted a link to it, consistency was the key and they cleaned the barrel every 6 shots. My main point is that conditions can never be duplicated but the Houston Warehouse mitigated many of them. Here are some of the 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.
Sorry, someone posted similar right before I did.
Go back and re-read the WHOLE Houston warehouse article..... YOU HAVEN'T BUSTED ANY MYTHS.......Why do you try to minimize or
what most here already know as good sound practices?
Everyone worth their salt on this site has had problems with powder by just changing lots, and I doubt you will find many who are willing to
buy 8 lbs of powder all from different lots on this site...... the only reason Virgil could buy 4198 and just use it with no apparent impact was because he had already tuned the the crappola out of that rifle in 20 different ways. Same deal on primers, a 15 or 20 fps difference in velocity
due to all the other things he had already done was not significant, and this was not a large magnum case with a lot of powder to burn, so even less impact from combustion process due to primer than a smaller 22 caliber centerfire case which was used in the warehouse experiment.
Re-Read all the process steps Virgil took with his Brass. They are in my post #17 above and here they are again:
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.
