DEVELOPING SUBSONIC LOADS FOR CENTERFIRE RIFLES

I recently became interested in developing subsonic loads for a couple of centerfire rifles I own. My wife enjoys shooting with me, but has a bit of problem with recoil and the high volume crack so common to hypervelocity centerfire rifle ammunition. Also, I’m an avid ‘coon hunter and thought it would be interesting to develop a subsonic load to hunt with. This would also lend itself well to general small game hunting and providing meat in a survival situation. So, toward these ends, I set out to develop some relatively quiet low velocity loads.

The purpose of this article is not to tell you how to do it, but to tell you how I did it. I don’t care for instructions that suggest “This is how you HAVE to do it.” With respect to safe loading and shooting practices, that is the case in some situations, but not always. With that in mind, I’ll share with you what I did and you can decide for yourself if you want to pursue this and in what manner.

This is a long article, but I deliberately took time to explain things in detail. If this proves to be useful to one person, I have met my goal.

CALIBER OF CHOICE

I chose the .223 Remington caliber to start with. The rifle I own in that caliber is an H&R single shot. The barrel has a 1:12 twist rate, so I thought it would lend itself well toward this experiment. The caliber does not require a large powder charge, so I would not be wasting a lot of powder in my experiments. Cast lead bullets for this caliber are usually about 50 to 55 grains, so again, I would not be wasting lead. Recoil is virtually nonexistent even in full power loads in this caliber, so that issue would also be eliminated. The caliber seemed to be the perfect candidate for this experiment.

COMPONENTS

BRASS

I have a fair amount of 5.56MM Lake City military surplus brass on hand. It’s good brass and relatively uniform in quality, so I decided to use that as opposed to commercially manufactured brass.

5.56 Lake City brass, decrimped and primed.

5.56 Lake City brass, decrimped and primed.

BULLETS

55 grain full metal jacket boat tail bullets are very common and relatively economical, so I chose that weight and style for jacketed bullets.

As for cast lead bullets, I chose two types. Lee Precision made a special order mold to cast what was named the “Bator” bullet. “Bator” is the user name of a member of the Cast Boolits forum and this gentleman designed the bullet. It is a 55 grain round nose flat point bullet with a gas check shank.

The other cast bullet I chose is also a 55 grain weight. It has a Spitzer nose with a bit of small meplat on it and a gas check shank. I have a good friend in a gentleman that is also a member of the Cast Boolits forum that goes by the user name of “X101Airborne” and he provided these bullets toward my testing. I deliberately loaded the cast bullets without gas checks to see if I could find accuracy with an unchecked bullet.

BULLET LUBE

Cast lead bullets require some sort of lubrication to keep the lead from coming off the bullet and being deposited in the barrel. There are myriad types of commercially manufactured lubes available and countless recipes for homemade bullet lubes. This article is about developing subsonic loads, but I’m going to spend a few minutes on bullet lube because I think it’s pertinent.

Like a lot of bullet casters/shooters, I have dabbled in my own experiments concerning bullet lubes. Very shortly before I started working on my subsonic loads project, I did some experimenting with powdered graphite as a lube component. Graphite is a dry particulate and is an excellent lubricant in certain applications.

The more or less standard application for graphite is between moving parts that are not under a lot pressure. The moving parts of firearm actions is an excellent example. The military uses it in conditions where oil would attract dust and/or sand and gum up the action.

I thought I might be able to make graphite work in a bullet lube, but the trick would be in making it stick to a cast bullet. Graphite has no to very little adhering factor and simply dusting a cast bullet with graphite was not likely to keep it on the bullet. How to make it stick?

Many years ago, I was introduced to a product called “Alox”. Alox is a dark brown viscous petroleum distillate with some other products added to it. As I understand it, Alox was developed to coat ferrous metals to prevent rusting. When applied as a liquid, it dries to a resinous, resilient film and adheres very well. Somebody discovered it serves well as a lube for cast bullets and it can be purchased for such use from a number of businesses.

It occurred to me that I might coat cast bullets with Alox and use it as a tacking agent to attach graphite powder. It took a bit of experimenting to develop a procedure, but I was eventually successful in this. I won’t get into that here as that’s another subject for another article. Suffice to say, though, my testing to date has been successful. I call my new lube “Graphlox”.

Below are the two designs of cast bullets lubed with Graphlox and the NATO ball bullets. Please forgive and disregard the fuzz on the cast bullets. That’s not intentional! Mr. Bill, my ‘gunroom’ cat, has a habit of leaving his hair lying around. The freshly coated bullets picked it up and it showed up in the photo.

Left to right are the 55 grain flat point Spitzers, the "Bator" bullets and the 55 grain NATO bullets.

Left to right are the 55 grain flat point Spitzers, the “Bator” bullets and the 55 grain NATO bullets.

Now, that extensive treatise done, we can move on.

POWDER

Knowing that using medium to slow stick type rifle powders in reduced charges is dangerous, at least without locators, I chose to conduct my experimenting with fast burning pistol and shotgun powders. I have on hand Bullseye, Red Dot, Unique and WC 820, a milsurp powder that was originally designed for the .30 Carbine cartridge. WC 820 is right next door in burn speed to AA9 and 2400, so I thought I could make it work. Having three different bullets and four different powders gave me 12 different combinations to try.

Pistol powders

Pistol powders

PRIMERS

I have on hand several thousand CCI brand small standard rifle primers. Not much more needs to be said about this.

ESTABLISHING A STARTING POINT.

Working up subsonic loads involves using very small charges of powder. The accepted practice is to increase the powder charge until you start seeing the desired results. So, the first thing I had to determine was the charge at which to start. I did a lot of research toward this, but found virtually no useful information. I found a lot of data established by others for subsonic loads, but none for a starting point in subsonic developmental experimentation. Like developing Graphlox, I had to establish a procedure for this also.

Obviously, the starting powder charge has to have enough energy to at least expel the bullet from the barrel. If it does not, the bullet will stick in the barrel. I had no idea how many charges I would have to go through to find a starting charge if I started with one grain of powder and worked up. So, instead of starting at the bottom and working up, I started somewhere above that and worked down, looking for the charge at which the bullet would stick. Once I found that charge, I would know where to start back up again.

I have a collection of close to two dozen handloading manuals, two of them dating back to the early fifties. I started looking through my available data for suggested starting charges for 55 grain cast bullets in .223 Remington caliber. All the data gave starting charges for velocities in excess of MACH I. For example, in the third edition of Lyman’s Cast Bullet Handbook, the starting charge for Red Dot powder is 5.4 grains for an estimated velocity of 1675 feet per second. I theorized that, if I cut that charge in half, it would still expel the bullet from the barrel. I loaded a single round with 3 grains of Red Dot, seated a 55 grain Spitzer cast bullet in the case without crimping the case mouth, grabbed the rifle and stepped outside.

Living in a very rural area of an agricultural county, I’m able to shoot on my own property. I loaded the test round, took aim on a tree about forty feet away and squeezed off the shot. It cracked like a .22 long rifle shot. I went back to my bench and loaded another test round, this time with two grains of Red Dot. That charge expelled the bullet, but the report wasn’t much more than a good pop. I loaded a third round with one grain of powder. The bullet stuck in the barrel. Two grains would be my starting point.

TEST CRITERIA

Through the years I’ve been handloading and shooting, I’ve seen a change of one tenth of a grain of powder make a difference in performance. I thought about that while considering how much I would change the charge from one test to the next. Not having any idea how many charges I would have to go through before I found the performance I was hoping for, I gave some thought to how to do this without having to fire a lot of ammunition.

I decided to increase the powder charges by one half grain per test. I would load five different charges, five rounds per charge, shoot the ammunition and analyze the results. If I did not find good results, I would load a few more test groups at higher charges and continue with my testing.

If I did, however, find a load that looked promising, I would load more test groups at one tenth grain charges on either side of the test group that turned in the best results. This would enable me to save some time and components, yet fine tune the loads until I found the best results possible. Example: Shooting test groups of 2.0, 2.5, 3.0, 3.5 and 4.0 grains of powder, let’s assume the best results were found with the 3.5 grain group. I would load eight more groups of test ammunition at charges of 3.1 to 3.4 grains in one tenth grain increments and four groups of 3.6 to 3.9 grain charges in one tenth grain increments. This would tell me exactly what the load is that works the best with the bullet and powder combination being tested.

LOADING PROCEDURE

Knowing that I would be shooting different groups of test loads, I knew it would be critical to keep track of the various individual loads and groups of loads. I needed a method of doing this to insure I would not get the different cartridges mixed up. I decided it would be best to mark each cartridge individually with a specific identifying nomenclature.

55 grain cast bullet over 2.6 grains of Red Dot powder.

55 grain cast bullet over 2.6 grains of Red Dot powder.

I could differentiate between the bullets by mere appearance. But I needed some method of differentiating between powder types and charges. That’s not something that can be determined once the round is loaded.

I marked each cartridge as it was loaded with the weight of the charge and a letter or two that would tell me what powder I used. For example, a load of 3.5 grains of Bullseye powder would be marked “3.5 BE”. If I happened to turn over the cartridge container, I could still sort them out. This also allowed me to put all the test ammunition in one container.

Prior to loading the cartridge cases, I marked all of them with the nomenclature using a Sharpie marker. The marked cases were then placed in a loading block in groups. I loaded all the cartridges and returned them to the loading block as originally organized. The loaded cartridges were then transferred to a plastic ammunition box with a ‘snap’ lid and transported to the shooting range.

I also loaded five rounds of ‘fouling shot’ ammo. I used the same powder I was loading the test ammo with and a charge of about halfway between the minimum and maximum of the test loads. This enabled me to foul the barrel and get it ready for the testing without having to use the actual test ammo. These fouling loads were fired at the berm with no purpose other than fouling the barrel.

TESTING PROCEDURE

Now that I had all the test ammunition loaded, I was ready to start shooting. I felt it was critical to do my very best, so I turned to a piece of equipment that would be a big help in steadying the rifle from shot to shot.

Caldwell Shooting Supplies, a business that manufactures supplies and equipment for the serious shooter, makes a rifle shooting rest called the “Lead Sled”. It’s made with a tray that can hold bags of lead shot which helps to reduce recoil. However, the rest can be used as a shooting rest alone. The Lead Sled has a vertically adjustable front rest for the rifle stock which makes getting the scope centered on the target very easy.

lead sled

I packed up the test ammo, my rifle, Lead Sled and range bag and headed out to my private 50 yard range on my property. I have a three-legged shooting table on my range. Having three legs eliminate the wobbling so common to four-legged tables. After getting the Lead Sled set up on the table, I put the rifle on it, got out the box of ammo and set up a target at 100 feet.

Before I go any farther, I want to explain why I chose 100 feet for the distance to the target. If you go back to the very first paragraph, I mentioned my wife’s enjoyment of shooting. She has a scope mounted .22 rifle and loves to shoot it. We both feel that we don’t need to shoot a hundred yards to enjoy it. Second, I mentioned ‘coon hunting. I’ve had the opportunity to fire a few shots at ‘coons that were relatively close, but I’ve never taken a shot past about 90 feet. Third, I mentioned small game hunting. Again, most small game shots are within a hundred feet or so. And fourth, I had no clue how these loads were going to group, so I felt 100 feet would be far enough to show grouping, but close enough to get dialed in on the target.

“The Target Barn” is another business I buy supplies from. They carry bullet hole pasters, 7/8″ square adhesive backed stickers that are used to cover bullet holes in paper targets. These pasters come a thousand to the roll, they’re very inexpensive and they make great bullseyes to shoot at. If you stick them on a sheet of paper with the points vertical and horizontal, it’s very easy to line up the reticles of the scope on these points. It makes for precise alignment.

PASTER EXAMPLE

In an effort to conserve time and target paper, I put multiple pasters on a single large sheet of paper. I spaced the pasters about four inches apart. That left plenty of room for groups and making notes on the target.

After shooting all of the groups of ammunition, I took time to document each target. I included all the information I might need should I ever need to back to the data. I then photographed each target and loaded the photos in my digital photos storage file.

DSCN1470

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About Jim

Retired from industrial construction and livin' the dream in the mountains of Virginia.
This entry was posted in Bullet lubes, Handloading, SUBSONIC. Bookmark the permalink.

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