Like everybody else, I useta' just BELIEVE this stuff....
"ever'body knows" that;
-firecracking/erosion causes pressure.
-copper fouling causes pressure.
-changing from a .237 to a .236 causes pressure.
-powder fouling causes pressure.
-moly decreases friction which lowers pressure
-"rough throat" causes pressure.
-tighter twist causes pressure.
etc etc.....and IT'S ALL SPECULATION!
It gets parroted year after year, over and over until we all "know it"......but it's crap.
Careful head-to-head testing shows it to be untrue. I, and others, have tested each of these items and found them to be not true. It's like "everybody knows that bullets go to sleep and some guns shoot better with distance...." But I've got an Oehler43 and $1000.00 cash that says IT'S CRAP!
(my friend with the Oehler43 just gifted it back to me (THANK YOU EDDIE!!!) and now I can shoot groups over two targets. My "$1000.00 and I'll buy your plane ticket, 2:1 odds" offer is back up.)
We all "knew" 20yrs ago that moly and "Danzak" and other "lubricants" lowered the pressure and velocity of a load. The corollary of course is that all the "firecracking/fouling/rough throat" stuff INCREASED pressure thereby raising velocity.
Harold Vaughn told me one time that the whole concept of "moly being more slippery and thereby dropping velocity" was not only flawed, but in his words "impossible." So, he TESTED IT and came up with a scientifically valid reason why typical moly'd loads lost a little velocity. He came up with a reason that WITH NO OTHER CHANGE except changing to moly'd bullets, velocity dropped. His testing was backwards validated over the last 10yrs as folks have begun meloniting bores..........a process which is extremely polarizing and weirdly enough just as many people say it DROPS velocity as say it INCREASES velocity.
Yup, two people in the same room at the same time, one will say "velocity decrease" and the other will say "velocity increase."
Search the innertube to see both sides..... here's a thread from right here, 6yrs ago.
http://benchrest.com/showthread.php?71954-Melonite-Barrel-Treatment
SCIENCE sez it INCREASES velocity, meloniting.......
But it's kinda' hard to test without REALLY GOOD velocity control.
In actuality it generally comes down to the specificity of the testing regimen. GOOD testing yields GOOD repeatable results. And the major impediment to GOOD testing is isolation of variables. I tried for years to achieve low ES "just because" I wanted to see if it was possible. I sorted and measured and weighed and bell-curved myself blue and pretty much came to the conclusion that getting low ES consistently was a pipe dream. WAAYYY to many variables and worst of all, some, like primer brisance and variable bore condition through a string are just about un-fixable.
Then there's all the grunting and whining about "how do you even measure it accurately ennyways??"
So, long story short I met this guy who actually showed ES under 10fps.
No BS
No whining
No issues A'tall, just long shot strings with very little variation.
WHAT th'?
So he tole me.
And I bought a scale.
Now I'm a guy who before all this happened I SOLVED the measuring problem by testing. And by improvising back-checks. I don't trust measuring ANYTHING, I like to gauge and compare against either a standard or multiple shots of the same thing..... And I don't trust the standards
So I check back.
For instance I tagged three similar chronographs one-behind-the-other to see how much they "varied" (while knowing full well they couldn't vary much) as well as using an Oehler 43. I can go down right now and shoot a bullet over three Chrony's, through the Oehler 43 and read the same shot with a LabRadar. 5 distinct and separate measures on the same shot. And I can know from experience that at least the Oehler and the three Chrony's are very repeatable. The LabRadar is still fairly new to me.
So ennyways, I bought a scale.
And now getting low ES and repeatable testable results is dead easy.......alla' that "how am I gonna' control this" stuff just becomes negligible when ONE CHANGE just wipes 90% of it out. The only thing I can remember being as big an eye opener in my shooting was when I first started shooting real BR gear. I remember having every excuse for fliers.....I'm ashamed to say I even "called fliers"...... and then I had someone build me a real gun. I found out what a PPC or a BR can do. And within that subset of "accurate rifles" I found out about "EASY, accurate rifles." I had a couple 22BR barrels, a 6PPC barrel and two 6BR's that would absolutely shoot dots part of the time before I got my first "easy" one, a Borden that couldn't hardly be forced to shoot bad....and this all with thrown charges. My typical ES with PPC/BR chamberings, thrown charges, is 45-80fps variance depending on the day.
But it doesn't matter, a good gun will compensate. The short-range 30's will too....
And then I got into longer range stuff.
IME it's kinda' hard to compensate beyond 500yds....some do, I ain't arguing with anyone's results, but I went another way. I went in search of consistent velocity and low ES.
And I found it.
IME, weighing powder charges right down to the kernel will eliminate 90% of all the variations but MORE IMPORTANTLY it allows one to actually TEST for things like copper fouling, powder fouling, bore treatments etc. It's pretty easy to see a 30fps change when your innate ES is 5fps, and MORE IMPORTANTLY the ES repeats day after day. But it's impossible to find these variations with thrown charges which vary by 50fps any given day and 100fps day-to-day.
And the really weird thing to me is......a buncha' folks in this thread will ARGUE about those ES figures when they've never tested it! I love to hear stuff like Jackie's testing of bullets over the chrono......I'll submit my opinion that the difference in velocity had to do with initial startup pressures (ie ogive/leade match, seat depth differences changing case capacity, etc) and not due to changes in bore friction from diameter/bearing surface differences. But that's my opinion. The big thing is, HE TESTED IT! And he found one bullet to be faster....awesome!
Testing is hard, and it takes time (years) to form opinions. Some dude says "I'd like to see data" simply doesn't understand what that means. I've got a stack of notebooks a foot high, thousands of rounds, hundreds of loads and combinations. "DATA??" this ain't like in the movies...... but ANY DAY OF THE WEEK, any time, anywhere I can easily show the effects between KERNELS of powder.
And so can anyone here, in the comfort of their own environment if they'll just take the time to DO IT as opposed to perpetuating myths.
Beg, Buy, Borrow or Steal a good scale.
Modify a chronograph by giving it an artificial source of illumination and
SHOOT!
Taking good notes.
BTW "good notes" IMO is absolutely NOT buying into some guys ideal of the perfect spreadsheet and filling in the blanks. It's NOT filling out a bunch of useless "dope" in a "Sniper's Data Log"....... it's just writin' stuff down. $.27 ringbinders bought 50 at a time at the Fall Back To School Sale are your friend. Don't THINK, don't COLLATE, don't itemize/organize/columnize/graph anything just WRITE STUFF DOWN. You've got hundreds of sheets, just date a page and scribble everything pertinent down. Turn the page, shoot some more, do it again. As the questions pop up, you write down the answers.
I've been hanging around this board of Wilbur's off and on for over 20yrs. I've watched a lot of myths die. I've seen a lot of folks mad when "secrets" have been revealed and I've got to meet some wonderful people who've tested stuff in ways I'd have never dreamt of (Skip Otto anyone? Dan Hackett? Charles Ellertson and his barrel-stretching buddies? Henry Childs? Yes, even Harold Vaughn came on a few times back in the day.......and I'm leaving a bunch out, some on purpose
) but what I've learned is, "ain't NUTTIN means NUTTIN until it's tested!"
Examples?? Let's just start with reloading rules, tips and tricks. How many reloading manuals will tell you "adjust the seating depth but BE CAREFUL NOT TO TOUCH THE LANDS BECAUSE PRESSURE WILL SPIKE!! SOMETIMES DANGEROUSLY!!" and how many people reading this right now just "know" that setting your case down to touch the shell-holder and then giving it enough to produce a "cam-over" is (good/best/necessary/useful etc) and that "spinning the case a quarter turn three times while sizing/seating will straighten" and "straighter presses make straighter ammo" and on and on and on........and then Neil Jones pioneered the concept of fitted dies (apologies to Palmisano/Pindell) and The Skipper comes out with something called "Skip's die shims" and ever'body sez "that'll never work!" And crooked ammo just becomes a thing of the past....for some people.
While others still argue on the innertube that "Redding dies are better than them cheapo RCBS dies"
What I'm saying Wilbur is that just a few years ago I had "fast barrels and slow barrels" that I thought were identical but in many cases they were not. What I'm saying is that IME
the variations come from the work that's been done on the barrel. The reason I'm currently so hot about my (Gordie's) chambering method is that for the first time in my life I can actually make chambers the same! In the past I've had many barrels chambered with the same reamer where the chambers vary by 3-4 thou in diameter. It's simple fact that if you set up a barrel between centers and run a reamer into a bore that wanders away from center that chamber will be bigger. Also (and I'm wayyy out on a limb here....) the throats will act differently, the ramp-up pressures may be different at least until the burrs are worn away. I'm not sure what all goes on but in my opinion the change occurs from the ogive back....it's not a function of barrel fit/finish. Right now, today I can make one chamber the same size as the next. Same throat, burr-free and same capacity all-round. And this ability, coupled with carefully monitoring charges has so far eliminated "fast" and "slow" barrels....
Time will tell and I'm happy to be corrected, but at this point I BELIEVE that fast and slow barrels aren't random. I currently believe they're built.
