View Full Version : Suppressed .300 Whisper M16 vs. Suppressed .45 Submachine Gun

November 8, 2001, 09:08 AM
I've been thinking. The subsonic .300 Whisper load (Cor-Bon's Load) puts a 220 gr. bullet out of a 16.25" barrel at 1040 feet per second. A .45ACP load, or a .45 Super load, could easily be pushed to similar velocites with a similar weighted bullet.

NEITHER load, in my opinion, has enough velocity to penetrate even soft body armor, so the advantage of the .300 Whisper being a "rifle cartridge" vs. the .45 being a "pistol cartridge" is lost.

Both cartridges are subsonic, and subsequently are short ranged (for those that don't know, velocity equals range, as the bullet will go farther in the time it takes gravity to pull it to the ground).

The .300 Whisper, being a smaller diameter bullet, might have a slight ballistics advantage.

But is that really worth them developing an entirely new cartridge for? I mean, if they wanted suppressed automatic weapons, wouldn't a suppressed .45ACP submachine gun be smaller, lighter, and have a lower recoil impulse than an M16 converted to .300 Whisper, or is there another factor I'm not considering here?

Bartholomew Roberts
November 8, 2001, 09:47 AM
Well, with .300 Whisper, you can just switch out the uppers on your M4. You don't need to change the magazine or lowers. Everything else works just the way the M4 works so you only have one weapon system.

November 8, 2001, 10:29 AM
Is that really any kind of a tactical advantage though? I mean, what are you going to do, carry an extra upper receiver and magazines in two different calibers, 5.56 and .300, with you on missions?

I can see how that would be a logistical advantage. But does the .300 Whisper hold any tactical advantages?

November 8, 2001, 10:37 AM
Actually, the 300Whisper is fairly accurate at a range of several hundred yards given the right bullet. Think supressed precision rifle. While I love my 45cal, they are close-range rounds.

November 8, 2001, 10:48 AM

November 8, 2001, 11:31 AM
There's no need to shout. But please explain to me how a subsonic 250gr bullet in .300 whisper will penetrate body armor "like it was cheese" when a subsonic 250gr bullet in, say, .45 Colt, won't? It can't be just the smaller bore diameter. Even .30 Carbine can be defeated by some Level IIIA soft armors, and that's a 110gr bullet moving at 1950 fps.

Penetration is a function of velocity, primarily, and mass second. Smaller bored, lighter bullets can get higher velocities and have less surface area for there to be resistance against, but big heavy bullets have more mass, which means more momenthum, which means more force is required to stop them.

A subsonic bullet in any caliber or weight is going to have a hard time defeating modern soft body armors, unless I'm sorely mistaken.

Keith J
November 8, 2001, 12:22 PM
A broadhead? I'm sure a field point would defeat soft armor. The key you were missing was sectional density.

As far as the .300 Whisper, its sole design was for head shots. Its wounding capacity is roughly identical to the .30 carbine.

November 8, 2001, 12:23 PM
NC: I have no idea if either will penetrate, but your logic IS sorely flawed. I'd be willing to bet that an ice pick will penetrate and it is only traveling at 50 fps ... I think that high enough velocities will allow anything to penetrate, but to say that veloity is primary and mass is secondary seems to be leaving the form factor entirely out of the discussion. Woven high strength fabrics are not going to behave linearly in their failure modes, so I think that any simplistic model of their failure (for example: It is just ...) will not adequately describe the issue.

As for range ... you aren't typically interested in how fast something is moving when it leaves the muzzle ... the proof is in the velocity at impact. Look at the ballistic coefficients of a 250 gr .45 round nose and a 250 grain .30 cal boattail ... now compare the retained energy at 200 yards ... ahhh ... the differences become apparent.

November 8, 2001, 12:54 PM
Well, I was referring only to bullets. An ice pick needs no high velocity, because its mass is so high compared to a bullet that it more than makes up for it. The heaviest bullets usually weigh less than one ounce (unless you get into .50BMG or elephant gun territory). An Ice Pick weighs several pounds. An ice pick is also very pointy, and pointy things can tear through the fibers of soft armor (pointy object vs. blunt object is not really an issue, I don't think, if the armor is ballistic steel; an ice pick isn't going to penetrate armor that will stop a .308 at point blank, but the blunt trauma could still wound.) Its true, I know very little about sectional density. A pointed bullet will have a better chance of penetrating soft armor than a blunt one, I know.

Beyond that, I know squat about ballistics. I attributed the velocity being more important than mass to the recurring statment here that a certain 5.56mm round will penetrate deeper than a 7.62x51mm round, though the 7.62 round has 50% more mass and is moving only about 400-500fps slower. I hadn't considered sectional density, as I don't know anything about it.

The question remains, though. How is one subsonic bullet better than another if they weigh the same?

It would seem that .300 Whisper retains its velocity better, due (I'm guessing) to, basically, a more aerodynamic bullet design. So that's one advantage.

But, another question: If .300 Whisper was intended soley for headshots, why bother with a new cartridge? Even a subsonic 62gr bullet from a 5.56mm M4 will kill with a headshot (won't it?).

November 8, 2001, 02:15 PM

And so did saands.

Massive difference in terminal performance.


November 8, 2001, 02:30 PM
As previous posters have mentioned, if you compare the ballistic coefficient and sectional density of the two rounds, the difference in their terminal performance, despite of similar muzzle energy (mass and velocity too), should be easier to grasp.

The 230 grn .45 ACP has a much larger cross sectional area than the 220grn .308, giving it a much lower sectional density (0.161 vs .331). Researchers into wound ballistics have found that bullets of equal sectional density will, ceteris paribus, penetrate equally in their test mediums, with bullets of high sectional denisty penetrating deeper than those with low sectional density. With our comparison, this becomes more apparent at longer range, when the bullet slows due to air resistence. Given the same striking velocity, a situation which will definitely not exist beyond a few yards, the .300 Whisper will out penetrate the .45ACP.

The 220grn .308 has a far greater ballistic coefficient than the .45ACP bullet. This is a ratio of the sectional density to its coefficient of form. Methods of calculating ballistic coefficient are rather controversial, as some experts argue that the shape factors used are antiquated and do not accurately model the ballistics of modern bullets, or that the ballisitics coeffiecient changes with velocity (which it does). Using the most commanly accepted method of calculating BC, the .308 Sierra Match King 220grn bullet has a BC of .608 at 1700fps or lower, where as a Sierra .45 230grn JHP has a BC of 0.169 @ >900fps. , or the same in Match Target configuration has a BC of 0.200 (its optimized for sub 1100fps range. Go faster and it goes to 0.141.)
Its enhanced BC means that it travels through the air much more efficiently and loses velocity due to wind resistence at a much slower rate. Run the two bullets through a ballistics programs with those BCs and look at the retained velocity, striking energy, and bullet drop at 50, 100 and 200 meters. The .300 Whisper will come out ahead of the .45ACP in every catagory at everything but the closest range. The .45s only advantage, in this case, is bullet diameter/wound channel.

As for penetrating body armor, due to the way the woven aramid fibers dissipate the impact, projectiles with high sectional density, or small cross sectional area generally have an easier time making it through. Some early body armors could stop a 230grn .45ACP but not a .22LR. A .30 Cal Carbine 110grn FMJ at 1900fps is BC .170, .166, yet it will penetrate most II and IIIA vests, where as the .45 Auto will not. It is not a linear relationship, and is very dependent on the construction and configuration of the vests protective panels. Bullet configuration also makes a big difference. Bullets with FMJ, or Specialty Armor Piercing configurations generally penetrate better than those in that are JSP or JHP. Hollow Points open up upon hitting the vest, hitting more fibers, which allows the fibers to disperse the energy across a wider area. The .300 Whisper may have been intended for silent sentry removal by pin-point head shots, but it should pentrate most types of soft body armor quite handily.

Why a .300 Whisper vs a Subsonic .223? Higher BC, SD, Terminal Energy, a flatter tragectory, and less wind drift at extended ranges. A subsonic 62grn .223 is effectively a heavy .22LR. I don't know how an M-16/AR-15 platform rifle would cycle firing subsonic .223s. Dedicated Subsonic Upper? There goes the savings in equipment.

November 8, 2001, 10:17 PM
The basic tactical role for suppressed "sentry removal" guns, and some interesting solutions to meet that role, have been around for a while.

During WW II, the OSS had .45 ACP suppressed M-1 Carbines. The Brits had the .45 ACP DeLisle , which was a suppressed Lee Enfield BOLT ACTION fitted to take Colt Govt magazines. With both of these, the native cartridge [ .45 ACP 230 Gr BALL ] was already sub-sonic.

Post War, the M-1 carbine was modified to shoot .44 Auto Mag and .45 Super. This gave a big bore carbine with substantial power. Silencing these beasties seems like a contradiction in opposing philosophies, because creating a semi auto Carbine that had enough gas port pressure to work reliably with big bore, HI Powered pistol cartridges, seems to rule out the requirement for sub-sonic velocities.

The .45 ACP starts out with a chamber pressure of 17,000 PSI. Most of the velocity is developed in 3" to 4". After that, the gas pressure falls to the point that a .45 ACP bullet is basically coasting. I used to build compensators for .45 ACP pistols, and believe me, there is not a lot of gas left at the muzzle of a six inch .45 caliber barrel to actually work the ports. Ultralight .45 bullets [ 155 gr ] with more powder can actually get a .45 comp working, but higher pressure smaller diameter rounds [ like .38 Stupid MAJOR ] really start to work, demonstarting that there is some effective residual port pressure with these.

So, to get a big bore SEMI AUTO carbine to function effectively at SUB-sonic velocities, there is a very thin power band where gas pressure is sufficient to work a semi action, and not too sufficient to exceed 1100 FPS. This is probably why BIG BORE suppressed firearms are better of in such things as an NEF single shot, where residual gas is vented, rather than required to work an action.
The sound of a semi auto action cycling is not really desirable for a suppressed weapon anyway.

But for those that need to "Whisper" and also need semi auto, there is the .30 Russian with a monster bullet.

November 8, 2001, 10:35 PM
you should check out J.D. Jones, SSK industries for info on the .300 whisper.


November 9, 2001, 12:54 PM
Actually, IMO Keith J hit on a good point if you really think about it.

If they are trying to make ballistic/polymer tipped rounds for the Whisper, I'm sure a normal .300 FMJ would go on and on and on relative to a .45.

November 9, 2001, 01:08 PM
I forget where but I have seen heavy subsonic 5.56x45mm loads before for sale, can't remember the bullet weight but I want to say it was between 90-105 grains. Does the action still cycle or is the ammo more effective than a 300Whisper driven at subsonic velocities, I don't have a clue nor have I seen any data. But I do think there are indeed some subsonic 5.56mm loads out there.

Likely Tungsten core so the 90-100grain bullets with the more dense material end up being about the same size as a 60-70grain bullet using less dense lead as a core.

November 10, 2001, 07:30 PM
I've once fired a box of them through my Steyr AUG. They are not very reliable.

Better turn off the gas port, put on a suppressor and then shoot. Thank God you can do that with a SIG 550 too. The only gun who'll make problems in that case is probably the AR.

November 10, 2001, 09:35 PM
Regarding body armor:

1. Knives, arrows, and icepicks WILL defeat body armor, unless the armor is rated for stab/cut resistance.

2. ANY rifle round will usually defeat the most common types of body armor.

3. Body armor maintains its effectiveness because it is designed to resist or at least slow down projectiles with large frontal areas moving at relatively slow speeds. Increase the velocity, and/or decrease the frontal impact area, and you have problems.

November 10, 2001, 11:02 PM
TERRY MURBACH: What were these original guns you fired ?

November 11, 2001, 01:28 PM
...checking out the .300 Whisper myself.

My current project gun is a Turkish Mauser action w/Kepplinger trigger and 16.5" Lilja heavy barrel in .300 Whisper.

Seemed like the thing to do when a Turk we ordered for stock turned out to have headspace issues... ;)

(I mean, hey, we had the .30 cal barrel and a couple of boxes of .300 Whisper lying around from an AR project that never got off the ground. Don't tell me the same idea wouldn't have occured to any of you... :D )