Short barrel ammo question
This is a discussion on Short barrel ammo question within the Defensive Ammunition & Ballistics forums, part of the Defensive Carry Discussions category; I was looking at Speer ammo for short barrels and wonder why they are for the heaviest bullets in the line. For .40 cal. S&W ...
November 5th, 2006 09:04 PM
Short barrel ammo question
I was looking at Speer ammo for short barrels and wonder why they are for the heaviest bullets in the line. For .40 cal. S&W the Speer short barrel is for a 180 grain bullet. For the .45 cal. ACP it is for a 230 grain bullet.
Why the heavy weight for each caliber? I would think in a short barrel the ideal choice would be a lighter bullet to get greater velocity from the short barrel. Maybe the heavy bullet choice is to reduce the recoil in the short barrel.
I did notice that in 9mm Luger the Speer short barrel is a 124 grain bullet in a +p load.
I tried to send this inquiry to Speer but no luck. Any guidance from those with greater knowldege?
November 5th, 2006 09:36 PM
lancek: Darn good question. I am asking a similar question as to what is more important with defensive ammo (or combat ammo as opposed to target ammo): penetration or projectile upset. It appears that expansion is winning the question. I am not completely satisfied. Out of a short barrel you may have little chance of tremendous expansion and therefore shot placement to vitals is more important...yes-no?
November 5th, 2006 11:24 PM
I always figured it was because they come out slower. I notice the FPS on the smaller bullets is always faster than the larger bullet. So since a short barrel results in less FPS the need is for the bullet to have more mass to maintain it and still have similar knock down. But then again... I just sort of made all that up in my mind... "}
November 6th, 2006 02:22 AM
Hopetonvrshoot and Cphilip are both pretty close.
The line of reasoning is that the heavier bullet's greater sectional density will make up for the depth of penetration which is lost due to the reduction in velocity.
Truth be told, I really wouldn't worry about it. The difference in performance from, say, a 4" barrel to, say, a 3" barrel is essentially academic.
November 6th, 2006 10:20 PM
Not tryin' to be a wise a$$ but here's my take on it.
I would suggest that we should not be obcessed with a few fps.
Pick the style CCW,the caliber,the bullet,the accuracy you want/need,and get on with it.
As stated before,if you gotta worry 'bout something,worry about your level of training and mindset.
Shoot 'em COM a couple or three times and they die. Nuff said. -------
November 7th, 2006 02:20 AM
AKsrule- Your hypothesis rides on the belief that velocity determines expansion. The "velocity -> expansion" belief is pretty common, but it is nonetheless flawed. Expansion is a factor of fluid dynamics.
In fact, it is resistance on the bullet from the media it passes through which determines expansion. Velocity does tend to increase this resistance, but the increase is marginal, as evidenced by the lack of a reliably-expanding bullet design until the mid-1990s.
The success of modern high-end hollowpoint bullets, such as the Gold Dot and Golden Saber designs, is not contingent on the velocity at which they travel, but rather designing the bullet to upset (begin to expand) with less resistance.
Hence, a bullet which will reliably expand in a standard loading and fired from a standard barrel length, will do so anyway with the reduced velocity from a shorter barrel. A bullet which won't, can't be driven fast enough out of the shorter barrel to ensure it. Therefore, increasing velocity is not critical to ensuring bullet upset.
If an increase in velocity were the sole, or primary, intent in designing short-barrel rounds, then LanceK would be correct, and the lighter bullet would be a better choice, as it may already be propelled at a greater velocity.
Instead, ammunition designers are seeking to ensure the "12 inches of penetration in ballistic gelatin" standard, which is often believed to be the crucial standard for ensuring performance in human targets (*read notation below), by enhancing the penetration qualities of the ammunition.
To ensure this depth of penetration, the ammunition manufacturers devise a powder charge which will burn faster than conventional pistol powder (in order to more thoroughly burn in the shorter barrel than would otherwise occur), and which will not produce an unsafe level of chamber pressure, and use it to propel a heavier bullet.
The heavier bullet provides greater sectional density (which is a measurement which compares a bullet's weight to its diameter), and sectional density is one of three critical aspects to bullet penetration (**see note below).
NOW, having said that, I must agree with RSSZ: Much of this is academic, and bears little consideration for the average protection-minded shooter. Those who spend excessive time contemplating the ammunition to choose, are usually the worst tacticians.
(* The 12" of gelatin penetration standard is, of course, one of the products of the new-ish study of the performance of ammunition on human beings, and attempting to create a corollative laboratory standard to predict the performance of new loads. The central problem with this is, as one might expect, the compilation of data on the subject. Due to the fact that there are literally many hundreds of service pistol loadings available today, and only a very few of those will be used in a statistically significant number of shootings, the assessment of the performance of the remainder is difficult to statistically sample, due to the exceptional number of uncontrolled variables involved in combat which affect statistical outcome. This fact is also, incidentally, the primary reason for the exceptional fallibility of the Marshall-Sanow study- the questionability of his sources taking a back seat.
As an aside, the last line of my post, regarding tacticians, is a quote from a magazine article Marshall wrote. Though I disagree with most of what Marshall has to say, I do have to credit him with that much.)
(** Many amateurs are of the erroneous belief that performance is a combination of either bullet mass and velocity (or kinetic energy), or a combination of bullet mass and bullet diameter. Or, in the case of 10mm shooters, a combination of all three. In fact, performance- which can best be described as the ability to deliver a bullet which a) penetrates deeply enough to reach the vital organs, and then b) significantly disrupts tissues at such a depth- is more a combination of three factors: velocity, sectional density, and ballistic coefficient. The reason why this is not more-commonly spoken about, is because none of these three variables is an absolute. Rather, it is the harmonious combination of these factors, in measured quantities, which affects performance. Too much or too little of one, in comparison to the others, throws off the entire equation.)
November 7th, 2006 05:37 PM
Thanks to all for the info.
The message as I understand it is short barrel ammo is specially engineered by: (1) having powder that burns faster; and (2) having bullets that are set to expand at the slower velocities generated from shorter barrels.
Since Speer knows more than me, I'll trust their engineering.
November 7th, 2006 06:03 PM
It would be more accurate to say the following:
1) Speer (and a few other manufacturers) already have a bullet which provides the optimal balance of penetration and expansion (penetrates deeply enough, but not too deeply, before beginning to expand rapidly);
2) Speer (et al) utilize this existing bullet, in the heaviest weight which they produce for a particular caliber, in order to increase the bullet's penetrative qualities (in order to make up for penetrative qualities lost due to velocity reduction);
3) Speer then loads the cartridge with a very fast-burning powder to assure the most thorough possible burning of powder (which increaes velocity in a shorter barrel), in order to assist the heavier bullet in achieving sufficient velocity to meet the 12"-of-gelatin standard of penetration.
Also, thanks for bringing this up, because I don't frequently get the chance to flex my (admittedly modest) physics muscles!
Last edited by Roundeyesamurai; November 8th, 2006 at 04:22 AM.
November 7th, 2006 07:11 PM
unless you are shooting a TC contender the barrel length is not an issue at 21 feet, shoot what you want.
November 7th, 2006 08:23 PM
I've been having trouble with Hydra-shocks not expanding from my 3" 1911. I'n fact, I've never seen a "real world" expanded hydra-shock. I'm also checking into short barrel ammo. If I find anything out, I'll let you know.
November 7th, 2006 09:11 PM
I do not believe that any of the short bbl loads use any different bullet or bullet design than the existing bullets that are already on the market.
I could be wrong 'bout this though. I can't confirm this from any bullet manufacturer. --------
November 7th, 2006 09:48 PM
I use Speer GoldDot hollow points in my snubbie, and Hydroshocks in my 380.
Originally Posted by RSSZ
My Basic CCW plan is as follows
1. Shoot them
2. Keep shooting them until they are down
3. If they get back up shoot them again.
1. Shoot at them
2. Run away
As a side note #2 in Plan B has been my plan B since I was 6. If it works don't change it.
I plan on putting my rounds Center Mass, I hope the bullets expand but I'm not to worried about it.
Last edited by pgrass101; November 7th, 2006 at 10:12 PM.
November 7th, 2006 10:06 PM
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November 8th, 2006 03:18 AM
RSSZ- That's correct. They've each engineered a bullet which expands reliably at reduced velocities (or more correct, with less hydrodynamic resistance). Because of this, there's no need to reinvent the wheel.
TJ1231- That doesn't surprise me.
November 23rd, 2006 05:35 AM
Shortbarreled versions of the gold dot are different designs than the standard gold dot bullets. For example the cavity on the 180gr .40 SB version is much larger than the standard gold dot which is why the seem to expand more reliably.
The ranger T and HST are tops regardless of caliber or barrel length.
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