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.357 Magnum: Defense and Practice Loads
By: Kevin Newberry
Finally! Thursday, May 30, we were able to get to the range. April showers were definitely a month late. I can not complain, considering that as I write this on Saturday, June 1, we’ve only had one of what I’d consider a SEVERE Thunderstorm. Some of the thunderstorms that passed through here in NW Central Texas (?) which is why I just call it Heart of Texas, have given us abundant rainfall, but became SEVERE later, further East of us. Those storms produced tornadoes. There were, however, SEVERE Thunderstorms that produced tornadoes close by, including one that caused significant damage in Abilene which lies NW of us by around 85 miles.
From my last article I increased the powder charges for the RMR 158 gr. Plated Hollow-Point (PHP) loads like the one in the pic above. I will be updating this article, because while I had some good results with the 140 gr. XTP loads, only those charged with True Blue distinguished themselves, so none were tested for expansion and penetration. More about that later.
In the past article with loads that could have been higher in velocity with the RMR PHPs, I was not really able to clearly demonstrate the premise that I’d hoped to. That can be, and will be corrected here. As far as the 158 gr. PHP, I was interested in getting higher velocity to make a better comparison of velocity with the two different barrel length revolvers. That, combined with RMR’s statement that while the 125 & 158 gr. PHPs are not designed for expansion, they can still mushroom. IMO, that would qualify the 158 gr. PHP for duty in dispatching feral hogs in the area. The 125s I’ll continue to use for practice loads.
RMR also recommends using jacketed bullet data for the PHPs. I did not push them quite so hard. The 158 gr. PHP load that I chrono’d from both revolvers had a 9.2 gr. Charge of True Blue. It chrono’d 1151 from the 4.2” GP100 and 1124 FPS from the 2 1/2” S&W M66-4. From the Western Powders 7th edition load guide you’ll notice that they loaded to a higher MAX Charge with the LaserCast 158 gr. SWC (9.8 grs) than they loaded the 158 gr. XTP (9.5 grs). Therefore, the loads I chrono’d from both revolvers were not a MAX Charge per Western load data. I did, however, want the charge to be “warm” enough to draw velocity comparisons from. And as you can see, that difference was only 27 FPS. The load was accurate from both revolvers. Accurate enough that I would certainly recommend it as a “practice” load. Higher velocity is possible as you get closer to the MAX Charge listed in the 7th edition load guide, but higher velocity is also possible without increasing pressure by switching to one of Western’s slower burning powders. Personally, I like powders in the True Blue to No 7 burn rate range for shorter barrel defense loads, especially when flash is not offensive. Pressure can run a bit higher, but you will not lose as much velocity if you use the same load in a shorter barreled revolver.
Let’s talk about primers. First off, I have a pretty good collection of past Accurate load guides. The one’s I’ve used most are the 2001 & 2002 editions. The reason for that, firstly, is due to the number of years I’ve used them as my data source, with comparisons made to the Lyman Pistol & Revolver III. In the 2001 edition, the handloads were chrono’d from a 6” S&W M686. The 2002 edition differs by stating velocities were chrono’d from an 8” test barrel. The velocities, however, are identical. Unfortunately, Accurate omitted the 140 gr. Load in the 2002 edition. Another difference is that a CCI500 standard small pistol primer was used throughout. There is a caution to use only Start Charges if a magnum primer is used. Western’s current data used a WSPM which is their small magnum pistol primer. In their .357 Magnum data. Lyman used the CCI550 magnum primer throughout. As you’re probably aware by now, magnum primers produce higher pressure which requires a lighter powder charge to be used. I should also mention that the Lyman P & R III lists 9.1 grs. Of True Blue as the MAX Charge for the 158 gr. XTP. I don’t believe that the disagreement regarding MAX Charges is significant. Two different pressure testing methods are used. Lyman tested in Copper Units of Pressure, or CUP, while the Western Ballistics Lab tests in PSI. You’ll notice an even greater disparity for MAX Charges for the 125 gr. XTP, and by 1 full grain of True Blue. Since it is somewhat fast burning in 357 Magnum loads, Lyman’s MAX Charge of True Blue at 10.5 grs. Is the highest charge I’d use or recommend, personally.
The fastest load with the 158 gr. RMR PHP came from Accurate No 9. I will caution you here that this load was safe in firing from MY Ruger 4.2” GP100. It is .5 grs lower than the MAX charge from the 2001 & 2002 Accurate load guides where a standard CCI500 primer is MANDATORY! I’ll also say that, IMO, there’s really nothing gained with higher charges while using a standard primer. You may find that different with larger cartridges like the .41 and .44 Magnums and large pistol primers.
Because of the data, I expected better performance using No 7 and No 9 and the higher velocities shown in the older load guides. The MAX charge listed for the 158 gr. XTP from the 2001 load guide is 15.0 grs. Using, as mentioned, the CCI500 primer. The velocity shown is 1633 FPS from the 6” S&W 686. The velocity I chrono’d on Thursday was 1256 FPS using a 14.5 gr. Charge. Quite a large drop off with a .5 gr. lighter charge and 1.8” less barrel length. Even by interpolation, which is simply a SWAG (scientific wild-ass guess), the 14.5 gr. Charge estimates a velocity of 1589 FPS from their test barrel, which may not be possible with the 1.8” extra barrel length. I certainly have my doubts. The larger issue here for me is that for the 10 round average velocity of 1256 FPS my Pro Chrono gave, Extreme Spread was 75 FPS and Standard Deviation was 22 FPS. Certainly not terrible, but I believe that could be improved by using a magnum primer and current data, Western or Lyman. In any event, a 158 gr. Bullet leaving the muzzle at 1256 FPS still produces 554 Ft/Lbs of muzzle energy. And while the RMR PHP may not expand, they have found that it mushrooms at higher velocity where 1400 FPS is the highest velocity recommended for any of their PHPs. I also worked up a load with the new Accurate 11 FS. The velocity for the MAX Charge listed in the No 7 load guide is 1407 FPS from a 6” test barrel. From the 4.2” Ruger GP100, velocity was 1187 FPS. Would a 6” revolver produce 1407 FPS? Since the disparity would be 220 FPS in additional velocity from a 1.8” longer and vented barrel, I’d say it’s doubtful. I do not, however, know anything more than length regarding the barrel the Western Lab used. And as always, work up your loads from a Start Charge. As a minimum, work up with ladder loads, 6 – 12 rounds at .2 gr. Intervals up to the MAX Charge if desired. You may find best accuracy along the way, and also consider the purpose of the load. For practice, you probably want the best accuracy that comes close to replicating the recoil of your defense load. And as far as defense loads, I tend to push them according to their performance threshold: extra energy and momentum are useful, so long as the bullet performs well.
For defense purposes, my shooting partner and I prefer 140 grs. of bullet weight for .357 Magnum Defense loads. It will certainly aid penetration over a 125 gr. Bullet. Another thing to consider here is how well a bullet is constructed. If I did use a 125 gr. JHP for a defense load, the Hornady 125 gr. XTP would be the standard to judge all others by. As velocity increases, expansion likely will as well. That will lead to less penetration. I’m not one of the 18” of penetration guys. Even with their newest defense load, the Hydra-Shok Deep, Federal designed it for 15” penetration. We also know from the vast number of shootings where the 125 gr. .357 Magnum round was very effective, penetration was barely over 10” in many cases. Bullet construction is the key here, and some 125 gr. JHPs are simply fragile. 140s provide better penetration. From 2 1/2” to 3” .357 Magnums, I would not personally use a bullet lighter than 140 grs.
Now we’ll get to those loads where I used Ramshot True Blue, Accurate No 7 & No 9 with the 140 gr. XTP. From past experience I can tell you that the XTP is not the greatest expander in the world. They are, however, very consistent in expanding to a maximum diameter. Hornady states 1.5x expansion as the expectation, while that covers a pretty broad range of velocity. I’ll provide expansion and penetration data after I make a necessary change in primers and shoot next.
I’ve always preferred using a magnum primer with True Blue, particularly for lighter loads and for .38 Special loads. This time, however, I ran across something in the Ramshot No 3 load guide that caught my attention. The same Max Charge that I would work up to, but using a standard, rather than magnum primer. The load listed used the Sierra 140 gr. JHP and was chrono’d from a 10” test barrel at 1543 FPS. I certainly knew that my load’s velocity would be a good bit lower, and using a different 140 gr. bullet, but I liked the standard deviation of 7 FPS as a goal from the load guide. So, with 10.3 grs. Where I chrono’d 10 rounds, average velocity was 1282 FPS from the GP100 and 1225 FPS from the 2 1/2” M66. What I was aiming for was 1200 – 1250 FPS from the M66. A reliable defense load that would still be fairly mild in terms of recoil. Not as much concern for the heavier GP100 that wears an excellent Pachmayr Diamond Pro grip that replaced the factory supplied grip that’s a good bit thinner. That velocity was obviously in the range I was looking for at halfway in-between, I just wasn’t sold with the standard deviations of 20 FPS from the GP100 and 23 FPS from the M66. So as we go along, keep in mind that the velocity difference for these two revolvers was 57 FPS. IMO, this is greatly UNDERemphasized by some when recommending powders for defense loads. Accuracy was very good, but I believed extreme spread and standard deviation might be improved. The lower you can get SD down to, the more similar the loads will perform. Also underemphasized, IMO. There are some who will tell you that lower standard deviation doesn’t have much effect on accuracy. When you see that claim, ask if the rounds were fired handheld on bags, or with the revolver mounted in a Ransom rest; thereby removing the human element other than sighting.
I also used a CCI500 with No 7. Velocity was 1267 FPS with 11.7 grs., also from the older data and .5 grs. Lower than the Max Charge. Velocity from the M66 was 1179 that gives a disparity of 88 FPS. Not getting as close to the velocity goal for the M66, along with the higher SDs with accuracy not quite as good, I knew that True Blue would still get the nod.
I was hoping for better things with No 9, but that didn’t quite work out. Nonetheless, the velocity difference was still a consideration. 1261 FPS for 10 rds from the GP100, 1145 FPS from the M66 for a total difference of 116 FPS. This is exactly how things should be considering the burn rate with these three powders. More importantly, when even slower burning powders are recommended for such loads, not only will the velocity disparity be greater, you’re gonna get greater muzzle blast/higher flash unless the powder has a flash deterrent like 11 FS. But from what I saw from the PHP loads, the MAX listed charge for 11 FS was just barely faster than the No 7 load and 69 FPS lower than the No 9 load. This is by no means a roadblock for 11 FS, and as of today, there is no Western data for 140 gr. JHPs. In .357 Magnum, and I had to take a different route for data. If the flash suppressant works as advertised, you’ll also get greater load density in the bargain. It may even turn out that a slightly compressed powder charge may be required. What it will definitely do, is allow you to view the powder charges as your loading. That to a lesser extent was the case with No 9, but not with True Blue and No 7. Is it worth the additional cost in using the greater charges that will definitely be required? I’ll leave that up to the guy making that decision. And I suppose that if enough of us request it, we’ll get data for 140 gr. JHPs, maybe even the XTPs.
So in conclusion, does burn rate have an effect on velocity? I certainly think so. And for now, True Blue is doing almost everything I want to see with the 140 gr. XTP with 4.2” barrels and shorter. If you have .357 Magnum revolvers in both barrel lengths, I would say that it’s not necessary to make two different loads.
Like I said, I’ll report back after water testing and running the data through Charles Schwartz’s Q-Model for the QAS statistics. Those loads will be charged with True Blue.
Now for the update. I worked up to Western’s MAX charge for the SIERRA 140 gr. JHP at 10.3 grs. Substituting with the 140 gr. XTP and with a CCI550 magnum primer. The gain was only slight with 30 FPS more velocity and SD only lowered by 2 FPS. Extraction got sticky with primers flattened more than I want to see. So back to the loading lab! I made another batch using the original load chrono’d: 10.3 grs. With a CCI500 STANDARD primer that chrono’d 1282 FPS. The load is plenty accurate. How accurate? You tell me once you’ve worked up the load.
For you guys that are really into the 18” of penetration thing, a load fired from each revolver gave a predicted penetration of just over 18” from Charles Schwart’s Q-Model. Where I like to see penetration contained to four 1 – gallon jugs, the load from the GP100 made its way into a fifth jug while the test bullet from the M66 lodged in the front wall of the fifth jug. Plenty of penetration.
So how do they grade out?
1282 FPS XTP 1225 FPS XTP
Average Recovered Dia.
129.6 grs. 130.1 grs.
1.8625 oz 1.8262 oz
3.0983 cubic inches 3.0378 cubic inches
291.72 Ft/lbs 263.94 Ft/lbs
123.83 kW 110.10 kW
ΔE15 = energy displaced from 1 to 15 centimeters.
Stop percentage prediction by shots fired:
1282 FPS XTP 1225 FPS XTP
God Bless. Be safe and good shooting to you all!