Reduced loads – Maybe you shouldn’t!
Category : Reloading
I have been blessed to have a pretty good assortment of knowledgeable, experienced, and helpful gun people in my life. Virtually all of them are more than happy to share their knowledge and experiences with anyone who will listen. And, Lord knows, many of them love to talk. The common phrase among my friends is that there is no such thing as a five minute conversation. I am among those guilty of being verbose (overly descriptive when discussing everything).
My gun smith buddy, Gus Norcross, one of the regular contributors for Firearms News magazine (he writes most of their gun smithing articles), is one such person who loves to share his knowledge. He recently shared with me an old book, “Handbook for Shooters and Reloaders”. Written by Parker O. Ackerly, and copyright 1962. It is a cherished First Edition, for which I am grateful.
In it, P.O. Ackerly discusses the subject of reduced loads. In definition, reduced loads means reducing powder amounts to less than starting loads. Disturbingly, the purpose of placing that discussion near the very front of the book is that under some situations, reduced loads can cause the gun being fired to detonate, blow up, or become severely damaged, often with the additional risk of damage to the shooter.
So, this article is a discussion of the dangers of reduced loads, and how to avoid those risks.
One of the wonderful things about reloading your own ammunition is that you can customize it for your specific needs. Whether that’s competition target shooting, big or small (or even dangerous) game hunting, or just general plinking. You can select bullet combinations not generally available from a factory. You can create rifle loads that are amazingly tuned to the harmonics of your barrel, making long distance shots accurate and easy. You can tune the timing of the cycling of the cartridge firing to the gun, making faster shots in a competition, and raising your score. And, you can adjust the felt recoil in any pistol or rifle so that the shooting is more comfortable, and the subsequent shots are more on target (especially important in a life saving self defense situation.) However, it’s that last purpose for customization (reduced recoil) that is of concern here.
It’s well known by reloaders that the industry watchdog, The Sporting Arms and Ammunition Manufacturers’ Institute (SAAMI), has established maximum pressures for each of the “recognized and accepted” cartridges. That translates to a maximum amount of any appropriate smokeless powder which yields that maximum pressure. You are always urged to NEVER exceed that maximum. To do so, even with a new firearm, risks damage to the firearm, and at the very least causes excessive wear on the gun. Using a CURRENT edition of a published, and therefore tested load data book is the best way to stay current with the SAAMI pressure specs for any cartridge. The method of testing for pressures has changed over the years. While this article won’t go into depth or detail on the nature of that pressure testing, suffice it to say that using a current edition of any published book or guide will provide you with safe reloading data, starting loads and maximum loads.
It’s at the lower end of the pressure spectrum where the the troubles can begin. The starting load, or more specifically, loads reduced LOWER than the starting load.
When seeking a most accurate load for your rifle, it’s advised to do a load development ladder, starting with….. the starting load. That’s why it’s called that. You keep increasing, in small increments, the amount of powder until you achieve the smallest group size, or start seeing signs of excessive pressures, whereupon you stop (even if you haven’t reached the maximum pressure load per the book). That’s all normal and proper.
The troubles begin when some reloaders attempt to reduce velocity and perhaps strive for reduced recoil by reducing the powder charge BELOW the starting load.
It’s common practice, when loading a bullet of slightly different weight than what was tested in the load data book, to start at a starting load that is 10% lower than the published starting load.
My better recommendation is to call the Powder manufacturer and ask for proper starting load data. They have a vested interest in keeping you safe, and usually have additional tested load data that was developed after the current edition of the reload data book went to press. Additionally, they can properly interpolate load data, and provide you with safe pressure data for any given powder, bullet, cartridge combination. So, if you are in a situation where you need some guidance, instead of making what you think might be an educated guess, contact the manufacturer. I’ll post the contact information for the powder and bullet manufacturers below.
While it’s counter intuitive, a heavier bullet uses LESS powder to achieve velocity than what is needed for a lighter bullet. That has to do with some of the laws of physics, especially those relating to pressures in a closed container. Scientifically, known as “Boyles Law”, it has several aspects that relate to other physics principles. The issue with heavier bullets is that another physics principle plays a role: “A body in motion tends to stay in motion. Conversely, a body at rest tends to stay at rest.” That’s one of Newton’s Laws. So, a heavier bullet needs TIME to get moving. And, if you try to get it moving earlier than it is otherwise inclined to get moving, the result would be higher pressures in the case. So, to keep the pressures in the safe zone, for heavier bullets, the powder load is reduced, as compared to a load for a lighter bullet. Check your load data book, and you will see that this is true for every heavier bullet weight, using the same powder.
Reducing the powder load too far below the Starting Load does some unusual things. From industry testing we know the following:
- Severely reduced loads cause the distribution of the powder in the case to cause irregular burning, creating irregular pressure waves.
- Normally, the friction contact between the bullet and the inside of the case neck is sufficient to hold onto the bullet until all of the powder is converted into gas pressure, sending the bullet safely on its way down the barrel.
- However, irregular pressure waves can cause the bullet to become dislodged from the case, and becomes a barrel obstruction. As the pressures continue to rise from the burning of the powder, the pressures can become dangerous.
- There are several factors which contribute to this phenomenon:
* Use of slow burning powder contributes to the irregular burning and pressure waves
* Low powder volume relative to case volume causes powder to become compacted during the initial ignition from the primer, and can cause very unusual burning and pressures.
* Standard primers might not provide enough ignition flame to properly ignite some slow burning powders.
The rifle on the left was damaged due to a much reduced load, poor primer ignition, and shooting on a cold day, which worsened the powder issue.
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CONCLUSIONS
If you cannot find specific load data for your powder and bullet combination, call the manufacturer for guidance. DO NOT reduce any powder loads lower than 10% below Starting Load for any reason. Use fresh powder. If possible, and if recommended in the load data book, use faster burning powder when dealing with light loads (meaning Starting Loads). Use fresh primers. Pay attention to primer recommendations in the load data book, especially when they relate to some slower burning powders. Remember, the term “magnum primer” doesn’t relate to the use of that primer with a magnum cartridge. Magnum primers provide more ignition chemical, and are called for with difficult to ignite and really slow burning powders. (For example, H110 for pistol cartridges typically calls for use of a magnum primer.) Here’s a link to a chart, showing burn rates of common powders: POWDER BURN RATE CHART
Be careful when selecting powders. Use a published reloading data guide or book. You want information that has been scientifically developed and tested as safe. Be careful when dispensing powder. Scales, whether digital or analog (balance beam scale), have an accuracy of +/- .1 grain. When dispensing powder, do not take shortcuts. Measure at least ten amounts of powder from your powder dispenser before making any decisions about how repeatable those dispensings are. Carefully check to avoid double charges and to avoid squibs.
If you are looking for reduced recoil, choose a different powder. Do not try to achieve lower recoil by dramatically reducing the powder load. As described above, serious pressure waves and spikes can and do occur. Also, do not use a dramatically reduced amount of powder trying to save powder, or for “test loads”. Powder is cheap, compared to your gun and fingers. Use the recommended amount of powder and get safe pressures.
There is one powder, Hodgdon’s “Trail Boss” powder, that is especially loved and revered by shooters for it’s low recoil. It can be used in all cartridges, as long as it’s usage instructions are followed carefully.
Here’s a link for Hodgdon’s usage of Trail Boss: Trail Boss Usage
Trail Boss powder comes in 9 oz and 2 pound containers. I use a lot of it. Especially in heavy recoil guns, including my 44 Magnum and 500 S&W Magnum revolvers. I have also loaded it in 22-250 rifle cartridges for a friends wife who had shoulder surgery. 22-250 recoi, using factory loads, is typically pretty light. But, they wanted even lighter recoil. Turned out that I achieved that lighter recoil, and provided a tighter group than they were getting with the factory loads. Win-Win.
Here’s the list of industry contacts for load data. Use the list. Call the technical people for safe load data. They will give you a starting load, and a max load. Please don’t stray from that information.
INDUSTRY CONTACT LIST FOR SAFE RELOADING INFORMATION
Safe reloading!
