Beat-Trash hits it out of the park!
Facts matter...Feelings Can Lie
(I'm not randomly necroposting, the glock 43 thread referenced here...)
DocGKR: Have you tested 147 gold dots from a 3 or 3.1" barrel? 2 of 5 failed to expand and overpenetrated in Shootingthebull's denim test, but he was using clear gel at that time. But if there is going to be any difference, I'd expect bullets to expand more in clear gel than organic...
147 HST's performed fine in organic gel but was on the short end of penetration (with larger expansion)
4 out of 5 147 Ranger T's performed fine in organic gel, penetrating deeper but expanded less (1 of the 5 bullets chrono'd slower and only partially expanded)
Just a quick statistics refresher: 99.7% of data is expected to fall within + or - 3 SD. That would be a spread of 3.8" penetration.
95% of data is expected to fall within + or - 2 SD. That would be a spread of 2.4" of penetration.
And that is assuming the distribution is random. So there is not much sense quibbling over a 2" discrepancy between 2 people on 2 different days with 2 different gel blocks (with unpublished bb calibrations). As Carveth Read noted, "It is better to be vaguely right than exactly wrong."
The 68, 95, 99.7 rule applies only to normal distributions where X is distributed randomly. If the distribution is not normal, you have to fall back on theorems like Chebyshev's which broaden the probability of data falling within 2 SD of the mean from 95% to 75% and from 99.7% to 89% for 3 SD.
That would make quibbling over a ~ +/- 2 SD discrepancy between 2 testers on 2 different days even more asinine...
Last edited by 0ddl0t; 03-08-2019 at 11:36 AM.
You've got this backwards;
As stated elsewhere in this forum in another thread:
Despite the manufacturer's claims found here: ( https://www.clearballistics.com/faq/ ) ―
Does your product replace ballistic gelatin used for testing ballistic data?
''Yes, it replaces traditional ordnance 240A ballistic gelatin 100%. Our product meets the FBI and NATO protocol for testing terminal ballistics of human tissue.''― Clear Ballistics Gelatin always fails to meet even the most basic standard for BB validation as a terminal ballistic test medium. Since it cannot rise to meet that elemental standard, Clear Ballistics Gelatin is of little value if one wants to obtain test results that are directly comparable to those obtained in proven/correlated soft tissue surrogates (10% gelatin, water). No statistical approach is going to change that fact.
What is the FBI protocol you follow for calibrating ballistic gelatin?
The FBI protocol we follow is firing a standard .177 caliber (4.5 mm) steel BB from an air gun over a chronograph at 590 feet per second (fps), plus or minus +/- 15 fps into the ballistic gelatin. The penetration of the steel BB must result in 8.5 centimeters (cm), plus or minus 1 cm, penetration (2.95 inches to 3.74 inches).
Last edited by the Schwartz; 03-08-2019 at 02:03 PM.
''Politics is for the present, but an equation is for eternity.'' ―Albert Einstein
Full disclosure per the Pistol-Forum CoC: I am the author of Quantitative Ammunition Selection.
''Politics is for the present, but an equation is for eternity.'' ―Albert Einstein
Full disclosure per the Pistol-Forum CoC: I am the author of Quantitative Ammunition Selection.
DocGKR is there one 9mm ammo in your testing that was better than the rest? Did one bullet design stand out from the rest?
Last edited by msciresa; 04-20-2019 at 11:44 AM.
Anyone try the newest blazer brass flat point 147? I know AE 147 replicates HST well, but I found the blazer a bit cheaper. Fps was the same as AE 147. Thanks