I really don't understand this post. What do the laws of physics have to do with variance?Originally Posted by QED
In any case, you are incorrect. Here is a quick excerpt from a published paper by Dr. Gene Wolberg that pretty clearly shows a 2" range in the penetration results of 147gr 9mm Winchester JHPs when fired into gelatin. This is normal...
Full article:
https://www.ar15.com/ammo/project/Fa...hester_9mm.pdf
When all significantly relevant variables are taken into account -- by the relevant laws of physics -- then there is NOT a whole lot of variance possible in the predicted result. That is generally the case when one specifies the relevant variables such as, for example, in the case of 147 grain HST, its impact velocity into bare standard gel, and RD after penetrating X inches in such gel. With those relevant "variables" fixed -- there is not much room for variance in X. A simple example: if you repeatedly throw a given solid spherical object (reasonable size and not "feather-weight") up into the air with a given velocity -- there will not be a lot of variance in predicted distance that the object will travel before hitting the ground; all significantly relevant variables are known and the laws of physics then don't allow much variance (outside of experimental error).
Incorrect, no. You misunderstood what I stated. Gene Wolberg, a former criminalist who did not have a doctorate btw, did report a variation between 12-14" in Winchester 147 gr. JHPs that were fired into bare gel. However, there is no indication that those JHPs had: 1. the same impact velocity, and 2. wound up with the same RD. And although those JHPs did not expand as robustly as some 9mm JHPs do these days, nevertheless, unless shooting through FBI protocols tests barriers -- those 9mm JHPs that were used some 30 years ago are just about as effective as most of the 9mm JHPs that are available today!In any case, you are incorrect. Here is a quick excerpt from a published paper by Dr. Gene Wolberg that pretty clearly shows a 2" range in the penetration results of 147gr 9mm Winchester JHPs when fired into gelatin. This is normal...
The two parameters mentioned are key variables in determining penetration, for any given bullet weight and shape -- and in the case I specified with 147 grain HST -- all those variables remained the same, and when that's the case, penetration should not vary significantly.
From MacPherson (IWBA 1998):" The standard deviation of the penetration depths is the best measure of consistency of bullet expansion and is small in bare gelatin for well designed bullets. The recommended value of this parameter is 0.6" which is easily met by well designed JHP bullets." Current 147 grain HST JHPs certainly are at the very least as consistent in expansion as MacPherson had in mind in 1998. The 0.6" figure DOES NOT assume same velocity or same recovered diameter of JHPs that are tested; if it did, then the standard deviation of penetration would be much smaller than 0.6", for reasons discussed in above post.
Is snakyjake back with a new name?
Assuredly, I have not posted anything as "Snakyjake." However, I have read all posts in this thread and can see why some evidently were annoyed with Snakyjake's evident lack of familiarity with terminal ballistics basics, his confusion over conflicting results in terminal tests of 147 grain HST rounds, and his persistence in his confusion. Clearly, 1.4 grains above nominal weight of 147 grain HST round is not a significant factor in penetration outcome, nor is Federal's HST poster penetration and expansion data particularly reliable, despite being used and deemed by many as reliable. Trying to reconcile testing results from different testers where the testing protocols are unknown or widely different, is futile, of course.
However, science and facts are mentioned quite a bit in this forum, so my point in this thread is factual and deals with very much a scientific validity issue involving a significant discrepancy in terminal results in bare gel. Since Dr. Fackler established a scientific basis, and D. MacPherson confirmed it, for valid, reliable, and repeatable bare gel testing, then such testing should produce predictable and similar results by different testers who employ a very similar methodology (which is the very basis of science). Thus if one such presumably proper methodology compliant tester fires 147 grain HSTs into bare gel and, for example, obtains an average result of 13.8" penetration @0.66" RD @ ~147 grain RW @ 1017 fps, while D. MacPherson's thoroughly experimentally verified and validated prediction gives 11.2" penetration @ same RD, @ essentially the same RW, @ same velocity -- then such a discrepancy is quite interesting for those who do consider terminal gel testing as having a basis in science. Incidentally, it's interesting to note that Dr. Fackler himself acknowledged that D. MacPherson's bullet penetration predictions are no less accurate than Dr. Fackler's own gel testing results. Like with the question of caliber adequacy, whether 11.2" or 13.8" (or whatever) is deemed sufficient penetration in bare gel is a personal decision and is not the issue here, of course.
I recently got a Ruger Pistol Caliber Carbine in 9mm. It may become a Home Defense gun if it continues to work well.
My normal carry load for pistols is Fed HST 147. Will this be OK in the Ruger carbine or will the longer barrel run the bullet too fast for normal expansion? I also have some Fed HST 147 +P on hand.
I'm also quite curious about 147 HST gel results out of various longer-than-pistol barrels...
I think you’d be OK running 147 out of a longer barrel. Given how little powder is left in the case after shoving that long bullet in there I don’t thibk you’d get much acceleration past 5” or so of barrel.
Ballistics by the inch made this graph:
I chronograped the HST through my Ruger carbine with a 16" barrel. 5 shots of each.
147 HST std. vel. went 1065 fps.
147 Plus P HST went 1046 fps.
Strange that the plus P was lower?
16" is a lot of barrel for a 147gr bullet/load...There just isn't much powder to burn. Lighter bullets, loaded with larger powder charges, do get a bit of a velocity bump in longer barrels. I don't have any idea why +P would be slower, but I can say that the velocities you've posted are similar to a Glock 19 or 17 with the same loads.
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