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A Tale of Two Bullets and Six Western Powders

By: Kevin Newberry

And what a great couple of bullets they are. Recently, I decided that I wanted to get back into shooting .357 Magnum revolvers in double-action mode. Luckily, Rocky Mountain Reloading has a couple of really good Plated Hollow-Points, or PHPs, that include cannelures. At the RMR website, you’ll notice the statement that they are not intended to expand, but with enough velocity, they can “mushroom.” And speaking of velocity with these bullets having thicker plating than others, RMR gives them a Max Velocity rating of 1400 FPS, which is faster than most factory loaded 158 gr. JHPs.

I’m writing here in advance of getting out to test the next batch of handloads. For the first 250 rounds I made, I used True Blue for 50 rounds with the 125 gr. PHP and 50 with the 158 gr. PHPs. The 125 gr. Charge I used was from a previous handload at medium velocity using the old 125 gr. Remington SJHP where I found that they have a practical limit of around 1275 FPS with those loads being chronographed from a 2 3/4” Ruger Speed-Six. 50 rounds were loaded with Accurate No.7 and the 125 gr. PHP and 50 more with the 158. I jumped a bit out of sequence because I had the new Accurate 11 FS to try, and currently, a 158 gr. JHP is as light as they used in the data. 50 rounds.


The 125s did very well, but the 158s could have been a bit warmer. For several of these loads I just used JHP Start Charges, except in the case of the 125s I charged with True Blue. I will load more of the 158s with higher charges of True Blue, No. 7 and 11 FS. All of these first loads had a CCI550 Magnum small pistol primer. That I’m also going to change in favor of warmer data where the CCI500 Standard small pistol primer was used, and followed up with a warning that if magnum primers are used, you should not exceed the Start Charge. In the case of True Blue, I always use a magnum primer in .357 Magnum loads. And for shorter barrel revolvers, I’ve made some outstanding loads with True Blue. Accurate, low-flash and when fired from barrels 4” and shorter, they do not lose as much velocity.

Another aspect of this article will concern velocity as the powders get slower in burn rate. We’ll also look at the velocity loss from loads chrono’d with a 4.2” Ruger GP100, and then from a S&W 2 1/2” M66-4.

I mentioned the former load with 10.1 grains of True Blue and the REM 125 gr. SJHP. The chronographed velocity from the 2 ¾” Speed-six was 1278 FPS. Extreme Spread was 45 FPS while Standard Deviation for the 12 rounds was only 13 FPS. Pretty good in my opinion considering the short barrel length. Soon after starting this project, I found that I had more of those loads that I chono’d back in August of 2013. Accuracy, as I alluded to was quite good. Fast forward to 3/29/19 and 12 rounds chronographed 1327 FPS, 49 FPS faster from the 4.2” GP100 than a 2 ¾” Speed-Six. Not a great difference there and what I was seeking with the True Blue load being in a more optimum pressure range. And anyone who knows me, likely knows how I feel about that one-of-a-kind handgun powder.

That’s an overview of the first 250 rounds. Due to an illness in the family of my shooting partner’s wife, we had to postpone our shoot scheduled for Thursday, April 4th. Those loads will be 50 rounds with the RMR 125 gr. PHPs over Accurate No. 9 and 50 with the 158. The next 50 will be 125s charged with Ramshot Enforcer and 50 with the 158. Last but not least, in an attempt to aid competitive shooters, I have 50 rounds made using the RMR 158 gr. PHP over 4.3 grains of Accurate No. 2, a CCI500 primer and an OACL of 1.445”.

It took us until 4/11/19, but we finally got out for the second round of testing. Second for me, anyway. The first thing we did was to allow Randall to get caught up with the loads from the 1st round.

Regardless of formulas or predictions for velocity loss from barrel length reduction, that might hold true for one brand and one model of handgun with differing barrel lengths. I trust my chronograph more than guesstimates. The velocity loss from the loads fired from the GP100 was greater than your typical formula, rule of thumb, whatever, shooting identical loads from the 2 1/2” M66. 141 FPS lower for the RMR 125 gr. PHP and 86 FPS slower with the RMR 158 gr. PHP for the loads charged with True Blue.

Something I wanted to focus on is how those differences become greater as the powders burn rates get slower. By that standard, with True Blue being the fastest burning powder (not in terms of its placement on most burn rate charts) I use personally in .357 Magnum loads, it should have the lower spread among the Western Powders used for this test.

Obviously, for testing purposes using a plated hollow-point, the bullets must be consistent, which they were in weight as well as diameter where mine measured .358”. I also conducted another little experiment by crimping some of the rounds with a LEE Factory Crimp Die, or FCD. I typically load .38 Special and .357 Magnum loads with an older set of Lyman dies with the resizing die having a carbide insert. Lots of conversations spread throughout the interweb gun forums in their reloading sections concerning the use of the LEE FCD. My opinion is this: for the FCD to do its job for jacketed bullet loads, it’s carbide insert dimension must be consistent with jacketed bullet diameter. When you load bullets that are larger in diameter, something will have to change dimensionally. Before poly-coated bullets were popularized, I would have never used an FCD to crimp handloads where bullet diameter was .358” or larger. One method that had come from handloaders who fired a lot of over-sized cast bullets at .358” was to remove the carbide insert to avoid swaging the bullet to a smaller diameter. The rule of thumb that I read consistently when I started handloading them is that a cast lead bullet needs to be at least .001” greater than the barrel’s groove diameter. That’s easy enough to find by slugging your barrel with a soft lead bullet, then measuring that bullet diameter with your calipers. Not quite so easy to do is measuring the individual cylinder throats to make sure that they are not so small that they swage bullet diameter lower when the bullet leaves its case on its way to the barrel’s rifling.

In following that I rule of thumb, I just never had any leading issues with magnum revolvers and most hard-cast lead bullets bought from commercial vendors having a hardness of 16 – 18 BHN, or the very hard LaserCast bullets. Some calibers are more problematic than others. We’ll save that for another day.

What I wanted to check is what would occur with a high quality plated bullet, where again, RMR states that their plating for these bullets is thicker than others while they rate Maximum Velocity at 1400 FPS. For factory ammo, you’ll find that the velocity differences for .357 Magnum 125 gr. JHP loads will be a bit +/- of 1400 FPS, so as far as practice rounds that best simulate the defense rounds you carry for protection, I find the Max Velocity rating entirely acceptable. Unless you are buying ammo from what some refer to as the “boutique” ammo-makers, or your firing loads from a longer barrel, 1400 FPS is higher velocity than you’ll chronograph with 158 gr. JHP or JSP factory load.

Before I drift too far away; after making some “dummy” rounds in .357 Magnum cases with the spent primer still in place for safety’s sake, I ran those “dummy’s” through the FCD to find that they did get swaged slightly once I pulled the bullets from the “dummy” rounds and measured diameter at .3575”. 5 Ten thousandths of an inch smaller. I found that to be totally acceptable as well because of the accuracy the PHPs were able to deliver on target. How poly-coated bullets might be effected, I can not yet say. That would also include the effect, if they swaged down to .357”, of the poly-coating protecting the bore from leading, or not.

Though I have not used a great deal of plated bullets in the past, that will change for .38 Special and .357 Magnum range loads. The cannelure on these bullets is a big positive, IMO. With good case-neck tension on the bullet combined with roll crimping into the cannelure, that will help ensure enough bullet “pull” using the slower burning powders. Something else I considered was RMRs stating that their PHPs are not designed to expand, yet with enough velocity, they can mushroom. My thoughts ran immediately to feral hogs. If they do show up at a buddy’s place, I wouldn’t hesitate to use the 158 gr. PHP for that. Considering the advice to use hard-cast lead bullets for game that’s been around since before my time, even, since the bullet mushrooms without expanding, it should prove capable, maybe even for whitetail. The credo I subscribe to when it comes to hunting bullets is that some expansion is better than no expansion. And to me, slight mushrooming would qualify as “some expansion!”

As usual, I’m running long here, so I will list the highlights from our testing as far as velocity loss between the 2 revolvers used with their differing barrel lengths. With the 125 and 158 gr. loads charged with Accurate No 7, velocity dropped by 104 FPS with the 125 and 89 FPS with the 158. For the 1st round of testing I was using a WSPM for all loads. Next time, I’ll load with #7 using the standard CCI500 primer because of some past data I have used. Higher velocities are certainly possible even with the magnum primer loads I fired, but with a greater powder charge. I believe that is what kept the velocity spread lower with the 125s than what we saw with the True Blue charge that was definitely a higher pressure load. Before I got to making the No 9 and Enforcer loads, I had already decided to use a standard primer and higher charges. The Start Charge shown in the Western data for 11FS resulted in slower velocity than I was expecting, and around 150 FPS less from the 4.2” GP100 than shown. In fairness I should point out that in the Western Data, the loads were chrono’d from a 6” barrel. It was the last round I tested in my first session. Velocity drop from the M66 at the second session with my SP was 76 FPS from the M66, which I would definitely attribute to the start charge vs a higher pressure load. With the Western data ranging from the 14.2 gr. Start Charge to 16.7 grs. For the Max charge, 2.5 grs. difference could be more than necessary, If you want to start that low, I would do it in ladder loads to get to the mid range data for 11FS before loading more than 5 – 10 loads at .2 gr. intervals.

At this point we started the second phase of testing using No 9 and Enforcer, both with a CCI500 primer. Velocity loss for the 125 was 174 FPS which was better defined by the greater charge-weights. From the 4.2” GP100, velocity was 1349 FPS, so I knew I was in a better range in terms of pressure. The 158 lost 191 FPS from the M66. The loads that used Enforcer were also indicative of lower pressure and lower velocity as the result. The velocity loss for the 125 was 239 FPS, and 219 FPS of velocity loss with the 158 gr. PHP. Again, IMO, pressure was not in an optimum range. Maybe try Enforcer loads with a magnum primer unless you plan to load the higher velocity loads that used a standard primer. You will more than likely see that a magnum primer was used throughout in the various load manuals like Lyman’s P&R III that I generally use for working up handgun loads.

Part of my reasoning for the powder charges I selected was to remove some of the guess work associated with loading plated bullets. Should I use jacketed or cast data? You’ve all seen the questions. So it shouldn’t be any surprise that both bullets performed best in the No 9 loads. And per my personal M.O. where I focus more on the bullets path as its flying through the skyscreens than how they land on target, while I’m just basically using the target as a reference point. But, at 50′ I essentially obliterated the 1.2” 10-ring that’s surrounded by the bold black 9-ring that’s 2.45” max diameter where very few shots strayed from that with the Accurate No 9 loads. I believe all of these loads have great potential, and next time I’ll use a standard primer with Accurate No 7. As far as highest velocity with the least muzzleblast, I’ve felt for a good many years that Accurate No 9 has a burn rate that is very well suited to .357 Magnum loads. Some may use magnum powders slower than I would, but I’ve found some advantage in varying powders by burn rate according to case capacity from .357 to .41 to .44 Magnum. The .41 Mag being the “tweener” allows for some great powder choices including Accurate No 9 for full power loads. Be aware, however, that if pressure is in a more optimum range, there won’t be a great deal of difference in velocity comparing loads charged with No 7 in .357 Magnum, particularly the closer you get to the Max Charge.

Last but not least, I’ll give the details for my attempt at a gun games load in .38 Special where I used the 158 gr. PHP, following the trend of heavier bullets to get a power factor of around 130, that provides an average velocity “cushion” as determined by the loads Standard Deviation; hopefully 10 FPS or less. I got that fairly easily using the RMR 158 gr. PHP, 4.3 grs. of Accurate No. 2, CCI500 primer and an OACL of 1.455”. The load was faster than necessary from the GP100 at 894 FPS/141 PF while from the 2 1/2” M66 velocity was 813 FPS with a higher SD of 15 FPS. With the power factor for that load being 128.5, I would pursue slightly higher velocity for the M66 and less for the GP100 depending on standard deviation. It was one heck of a lot of fun to shoot from both revolvers after finishing up the testing of the .357 Magnum loads.

God bless, be safe and good shooting to you all!


Kevin Newberry