Perhaps this will explain.
Excerpts from the Dec. 2nd article
The New .327 Federal Magnum in Rugerâ€™s SP101 Compact Six-Shot Revolver
By Jeff Quinn
Immediately after the new cartridge was announced, the shooting forums were filled with shooters, and some who pretend to be shooters, denouncing the new cartridge as everything from being too loud to it being almost useless; all this from people who had never seen the gun nor the cartridge, much less having ever fired one. Some of us, including myself, were almost ecstatic hearing the news of the little .327 Federal Magnum. Those whom I know personally, like my friends Terry Murbach, Al Anderson, and Fermin Garza, who got excited about the new cartridge are actually shooters. These men shoot more ammunition in one year than most shooters will ever see in their lifetimes. All three of these gentlemen, while owning and shooting many big bore revolvers, are also great fans of the little .32 H&R cartridge, and immediately recognized the potential for the new .327 Federal Magnum. These three friends are scattered geographically around the United States, but we all know each other through our love of firearms, and our inclusion in that brotherhood known as "The Shootists". I mentioned these men here because they are true experts on guns, and revolvers in particular, but also would consider themselves as students of firearms, always willing to learn and experience new advancements in cartridge design. I contrast this with the pseudo experts who sit readily by their respective keyboards anxiously awaiting the opportunity to knock any new gun or cartridge that is introduced.
Having stated the above, the question is bound to be asked; "What is the .327 Federal Magnum good for?" That is always a fair question, even if it is grammatically incorrect. The simple answer is that it can do anything and everything that the .32 H&R cartridge can do, but do it better. It has more pressure and more case capacity, resulting in more bullet speed. Lots more bullet speed. More velocity makes it hit harder and penetrate deeper, with the right bullet. The .327 Federal Magnum will probably supplant the .32 H&R in every area except for the game of Cowboy Action Shooting, where light bullets and low velocities are preferred. However, Cowboy Action Shooting is only a game. The .327 Federal Magnum is made for more serious applications. It offers more power than the .32 H&R, with less recoil and muzzle blast than the .357 Magnum. In the SP101, you get six shots of .327 Federal as opposed to five shots of .357 magnum, but the main attraction, for defensive purposes, is that the .327 promises true magnum penetration without the recoil of the larger magnums.
Some "experts" claim that the new cartridge is not needed, as we already have the .30 Carbine and .32 WCF (.32-20) cartridges. First, the .30 carbine is a good cartridge, but it has no rim, is slightly tapered, and would require moon clips for reliable, quick extraction in a double action revolver. While the case capacity of the new .327 Federal Magnum and the .32-20 are close to the same, loading the .32-20 to the higher pressures required to achieve the velocities desired from a three inch barrel would destroy many of the old guns that are chambered for the cartridge. The .32-20 is also tapered, being primarily a rifle cartridge. Lengthening the .32 H&R into the brand new .327 Federal Magnum was the logical choice.
For a defensive handgun, I always lean towards penetration. I am asked everyday to recommend a defensive cartridge to those who are needing a handgun for protection. If a person can easily handle a small .357 magnum revolver, that is a good choice. However, the question of recoil often enters into the choice of cartridge. While in a service sized revolver the .357 is easily controlled, in a smaller package it can be a handful. Many times, I recommend a .22 Magnum for those who, for whatever reason, cannot handle or desire a hard-kicking gun. The .22 Magnum penetrates well, and getting the bullet to the vitals as deeply as possible damages more nerves, organs, and blood vessels. A bullet that does not penetrate does not tear up as much flesh. The new .327 Federal Magnum promises penetration, with less recoil than the .357 Magnum. That, along with good bullet design, should make for a dandy little defensive gun.
Regarding the Ruger SP101 revolver, it is probably the toughest, most reliable compact double action revolver on the planet. Weighing 28 ounces with a three and one-sixteenth inch barrel, the SP101can easily handle a steady diet of the high pressure .327 Federal Magnum. The weight is heavy enough to help tame the recoil, but light enough to carry easily and comfortably in a belt holster. I regard the SP101 as being a bit heavy for everyday carry in my pants pocket, but for wintertime carry in a coat pocket, or in a compact inside-the-pants holster, it rides easily. Made primarily of stainless steel, the SP101 is highly resistant to corrosion from sweat and damp weather, as any carry gun should be. The synthetic rubber grip is an excellent design, combining a compact size with a comfortable hold. Even in the .357 Magnum version of the SP101, the grip design is very comfortable to shoot. The barrel is of a heavy profile, and also aids in accurate rapid fire. The sights are pretty easy to see for a compact defensive weapon, and the rear is adjustable for windage correction. The trigger pull on the sample gun measured a smooth nine pounds, six ounces in double action mode, and a crisp three and three-quarters pounds in single action mode. The sample SP101 has a very good trigger action. The barrel/cylinder gap measures five one-thousandths (.005) of an inch. The cylinder bolt notches are offset, and not directly over the chambers, making for a stronger design.
Federal is offering three factory loads for the .327 Federal Magnum at this time; a Federal Premium 85 grain Hydra-Shok hollowpoint at 1330 fps, a Speer Gold Dot 115 grain hollowpoint at 1300 fps, and an American Eagle 100 grain jacketed soft point at 1400 fps. These velocities are advertised as being fired from the 3 1/16 inch barrel of the SP101. I only had the American Eagle load for testing. It chronographed at an average velocity of 1374.9 fps at eight feet from the muzzle, so corrected to muzzle velocity, the Federal specifications are dead on accurate.
With all of the negative comments early on from folks who have never fired the cartridge, there was a few things that I particularly wanted to test; those being muzzle blast, recoil, and penetration. I compared the muzzle blast of the .327 Federal Magnum to the .357 Magnum fired from guns with equal length barrels. I used for this test two Ruger SP101 revolvers, identical except for the cartridge. Holding the decibel meter beside the shooterâ€™s head, the readings seem close, with the .327 registering 120db and the .357 reading 124db. However, decibel readings are logarithmic instead of linear, and 124db is noticeably louder than a reading of 120db. The .327 Federal Magnum does indeed have less muzzle blast than does the .357 Magnum, at least using factory loads with the same bullets weights.
Measuring recoil was more subjective, meaning I did not have any instrument to measure the recoil. However, recoil has to abide by the laws of physics, and can be calculated. Both guns having equal barrel lengths and almost identical weights, the .357 Magnum has more recoil using equal bullet weights because it will fire a 100 grain bullet about 200 fps faster than the .327 Federal Magnum. The difference in felt recoil to the hand is also noticeable. The fly in this ointment is that the .357 Magnum is hardly ever used with the light-for-caliber 100 grain bullet. To get better penetration, most shooters use at least a 125 grain bullet in the .357 Magnum, and recoil with that bullet is heavier than the recoil of the .327 Federal Magnum using the 100 grain bullet by a considerable margin. Keep in mind here that in all these tests, I am using factory ammunition. I will get into the handloading portion a bit later. To keep things fair and in perspective, only factory loads were used in the recoil and muzzle blast tests.
Next I moved on to testing the .327 Federal Magnum for penetration. As mentioned early on, I am a believer in penetration above all else when it comes to a cartridge that will be used against flesh. The .327 Federal Magnum is marketed as a defensive revolver, so it had to be tested in flesh. Since shooting live humans is illegal, immoral, and distasteful, and fresh cadavers are hard to come by out in the woods, I rode into town and bought a whole pork shoulder from the local butcher. I told him that I wanted the biggest one that he had. It weighed just over twenty-three pounds. Again, I used only the Federal factory American Eagle 100 grain load for this test. I had three reasons for this: I wanted to use a load that is available to anyone who buys one of these revolvers, most people will carry their defensive handgun loaded with factory ammunition, and meat is expensive. Taking aim from a distance of ten feet and aiming just inside the shoulder blade, I fired into the pork shoulder from the end. The American Eagle jacketed softpoint bullet fully penetrated the shoulder. I had hoped to be able to stop the bullet and see just far it would penetrate the meat, but sixteen inches was the entire length of the shoulder. The entrance and exit holes were very similar, with some cratering around the entrance. Opening up the shoulder, about seven inches in showed a large amount of cavitation and tissue damage. Seven inches is about optimum for this. Measure into your chest about seven inches and you will see that there is a lot of important stuff in that area.