Efficient and Inefficient Reloading Powders
By Gary Zinn
Various reloading powders are more or less efficient at propelling given weights of bullets in particular cartridges. This general statement should be no surprise to most serious shooters and reloaders. What l have never seen covered in depth is specific documentation of the relative efficiencies of powders over a range of popular cartridges, so I decided to address this topic.
The distinctions of interest are made clearest when powder charges that are needed to drive a particular weight bullet at a specific muzzle velocity (MV) are compared, for a particular cartridge. I extracted the data to make these comparisons from the Hornady Handbook of Cartridge Reloading (10th edition, 2016). The Hornady Handbook is especially useful for my purposes, because each cartridge/bullet weight table therein lists the charges of various powders that will drive the particular weight bullet at certain MV increments. These increments are mostly 100 fps, including what is judged to be the maximum MV for the cartridge and bullet weight, and for a few 100 fps (sometimes 50 fps) increments below the maximum.
Generally, I did not use the maximum MV data set for each cartridge and load, but instead chose a MV that fell one or two increments below the maximum. This was done to include a larger number of powders in the analysis, since sometimes only one or two powders would generate the maximum MV listed.
The Hornady tables generally list the powder with the lightest charge weight needed to drive a given bullet, at each velocity, at the top of the table, with powders using heavier charges to achieve the same velocity listed in sequence below. This feature of the Hornady Handbook tables makes data mining easy.
I chose to document relevant information for popular centerfire cartridges in rifle calibers from .224 to .308. I included one specific cartridge in each size, except I listed two in .224 and 7mm, and four in .308 caliber. I chose a single appropriate bullet weight for each cartridge, except for the .243 and .257 cartridges, where I listed two bullet weights, one suitable for varmints and the other for Class 2 class game (up to deer size, at least). I also analyzed the seven most common handgun cartridges.
The data set for each cartridge is organized as follows:
Row 1 identifies the cartridge, bullet weight and MV in question. The number in parentheses at the end of the row indicates the number of loads (different powders and charge weights) that achieve the specified MV. Some tables in the Hornady Handbook have fewer than 10 powders listed, while others show more than 10 powders. I chose to truncate the comparative analysis at the tenth powder when the latter occurred.
Row 2 begins with the notation +E, to identify this as the most efficient powder in the group. The charge weight of the specific powder is listed and then the efficiency of the powder is indexed by showing the number of feet per second of MV that the powder generates, per grain of powder charge (fps/gr.) The number at the end of row 2 expresses, in percentage terms, how much more efficient this powder is than the less efficient powder listed in row 3.
In Row 3, the -E notation identifies the least efficient powder in the list of powders. The charge weight and specific powder are listed, plus its fps/gr. number.
.223 Remington: 55 grain bullet at 3100 fps (10 loads)
+E: 20.0 grs. IMR 4198: 155 fps/gr. (22%)
.22-250 Remington: 60 grain bullet at 3500 fps (10 loads)
+E: 32.9 grs. Accurate 2520: 106 fps/gr. (14%)
.243 Winchester: 75 grain bullet at 3300 fps (8 loads)
+E: 36.9 grs. H4895: 89 fps/gr. (22%)
.243 Winchester: 100 grain bullet at 2900 fps (10 loads)
+E: 40.8 grs. H4350: 71 fps/gr. (8%)
.25-06 Remington: 75 grain bullet at 3600 fps (8 loads)
+E: 49.1 grs. IMR 4320: 73 fps/gr. (18%)
.25-06 Remington: 117 grain bullet at 3000 fps (10 loads)
+E: 50.0 grs. IMR 4350: 60 fps/gr. (9%)
.260 Remington: 129 grain bullet at 2800 fps (8 loads)
+E: 38.9 grs. Alliant RL-15: 72 fps/gr. (24%)
.270 Winchester: 130 grain bullet at 3000 fps (10 loads)
+E: 46.8 grs. IMR 4064: 64 fps/gr. (28%)
7mm-08 Remington: 139 grain bullet at 2800 fps (10 loads)
+E: 40.6 grs. Accurate 2495: 69 fps/gr. (17%)
7mm Remington Magnum: 154 grain bullet at 2900 fps (10 loads)
+E: 59.1 grs. IMR 4451: 49 fps/gr. (14%)
.30-30 Winchester: 150 grain bullet at 2250 fps (5 loads)
+E: 31.8 grs. VIHT N-135: 71 fps/gr. (22%)
.308 Winchester: 150 grain bullet at 2700 fps (10 loads)
+E: 43.3 grs. Accurate 2495: 62 fps/gr. (5%)
.30-06 Springfield: 180 grain bullet at 2650 fps (10 loads)
+E: 50.0 grs. IMR 4064: 53 fps/gr. (15%)
.300 Winchester Magnum: 180 grain bullet at 3000 fps (8 loads)
+E: 68.4 grs. IMR 4451: 44 fps/gr. (16%)
.338 Winchester Magnum: 225 grain bullet at 2800 fps (6 loads)
+E: 68.6 grs. IMR 4350: 41 fps/gr. (8%)
9mm Luger: 115 grain bullet at 1100 fps (10 loads)
+E: 4.1 grs. Titegroup: 268 fps/gr. (34%)
.38 Special: 125 grain bullet at 900 fps (10 loads)
+E: 4.7 grs. IMR 700-X: 191 fps/gr. (38%)
.357 Magnum: 125 grain bullet at 1400 fps (9 loads)
+E: 10.7 grs. VIHT N-105: 131 fps/gr. (79%)
.40 S&W: 180 grain bullet at 1000 fps (10 loads)
+E: 5.9 grs. CFE Pistol: 169 fps/gr. (22%)
.44 Remington Magnum: 240 grain bullet at 1350 fps (10 loads)
+E: 14.1 grs. IMR 800 X: 96 fps/gr. (69%)
.45ACP: 230 grain bullet at 850 fps (10 loads)
+E: 6.2 grs. Unique: 137 fps/gr. (27%)
.45 Colt: 200 grain lead bullet at 1050 fps (8 loads)
+E: 7.5 grs. Titegroup: 140 fps/gr. (52%)
The differences between the fps/gr. ratio for the most and least efficient powder for each rifle cartridge/bullet combination listed range from 5% (.308 Win./150 gr. bullet) to 28% (.270 Win./130 gr. bullet). The differences average 16% for all rifle load sets.
In general, I think that one need not obsess about the relative efficiency of the powder used for loads for the .243 Win./100 gr. bullet, .25-06/117 gr. bullet, .308 Win./150 gr. bullet, and .338 Win. Mag./225 gr. bullet. The fps/gr. ratio differences between the most and least efficient powders listed are less than 10 percent for these loads, which tells me that powder choice is not critical. Conversely, anyone who loads other rifle cartridge/bullet weight sets listed may want to study and make some informed decisions about which powder makes the most sense (and cents).
Turning to the handgun calibers, the differences between the fps/gr. ratio for the most and least efficient powder for each cartridge/bullet combination listed range from 22% (.40 S&W/180 gr. bullet) to 79% (.357 Mag./125 gr. bullet). The differences average 46% for all handgun load sets. I did not fully appreciate how large the efficiency ranges of handgun powders are before I crunched the numbers. We who load handgun ammunition should pay attention to the relative efficiencies of the powders suitable for the calibers we load.
There are many avenues of discussion for these data sets. I will focus on just a few.
The obvious benefit of identifying and using the most efficient powders for any given load is getting the most bang for the buck (pun intended) in powder used. For instance, Hodgdon Titegroup is the efficiency champ for normal power 9mm pistol loads; the load listed above would yield 1700 rounds of ammo per pound of Titegroup. At a price of about $20 per pound, the cost of Titegroup powder for loading 9mm would be about $1.18 per 100 rounds. This is excellent economy, especially when compared with the least efficient powder shown, Vihtavuori N-350, which uses a third more powder per load and is almost twice as expensive per pound.
I can vouch for Titegroup as an effective and economical powder, not only for 9mm loads, but also for moderate power loads in 38 Special, .357 Magnum, .40 S&W and .45 Auto. Efficient powders for one cartridge and bullet weight may be quite good for others, too.
I have found that Alliant RL10-X is an excellent powder for .223 Remington loads. 22.2 grains of RL10-X will drive a 55 grain .223 bullet at 3100 fps (per the Hornady Manual). This is only 0.2 grains more powder than IMR 4198, the highest efficiency powder for the .223. I shoot loads with RL10-X powder in three different .223 Rem. rifles and it performs well in all of them, getting very consistent accuracy with bullet weights ranging from 50 to 63 grains. The point is that more than one powder may be both highly efficient and effective in a given cartridge.
Another use of information about efficient loads is to manage shooting comfort of more powerful cartridges, i.e., reduce recoil and muzzle blast. By choosing an efficient powder, one can have improved shooting comfort without loss of downrange performance.
An example is the .270 Winchester, with the least efficient load listed (60.1 grains of H4831) driving a 130 grain bullet at 3000 fps. Assuming a rifle with a field equipped weight of eight pounds, this load would generate 18.9 ft. lbs. of recoil energy. By contrast, a 46.8 grain charge of the most efficient powder, IMR 4064, gets the same MV with recoil of 15.4 ft. lbs. Using the most efficient powder for the load reduces recoil by 3.5 ft. lbs. (18.5%) in this instance, a very noticeable difference. The downrange velocity of the loads would be the same, of course.
The artful reloader can also tame powerful, hard kicking cartridges by using efficient powders at further reduced velocities (e.g., a 200 fps decrease in MV will decrease recoil of high intensity cartridges noticeably), or by using lighter bullets at reasonable velocities. Of course, loading the cartridge down will decrease the maximum point blank range (MPBR) and downrange energy, but the tradeoff may be worth it to get a milder shooting load. Most of us shoot milder loads better than we do hard kicking, painfully noisy ones, so we will likely be more accurate and deadly shooters when using the softer stuff.
Going in the opposite direction, one can load to get the most power attainable from a given cartridge/bullet weight combination. For instance, Hodgdon Superformance powder can be used to drive bullets very hard in the .30-06. Hodgdon load data show that 59.7 grains of Superformance will push a 180 grain bullet at 2840 fps MV in the .30-06. This is 190 fps (7%) faster than the 2650 fps that 50.0 grains of IMR 4064 generates, per the Hornady Manual data. The Superformance load allows a 17 yards longer MPBR and generate some 260 ft. lbs. more energy than the IMR load (both at +/- 3" MPBR).
Those are the benefits of the hot Superformance load. The downside is that Superformance is a relatively inefficient powder. It ranks tenth in efficiency among the powders listed for the .30-06 in the Hornady Manual. This means that using Superformance would mean using a lot of powder per cartridge. Yes, maximum loads of the powder get impressive MV, distance and power. The trade-off is disproportionally high recoil (24% more than the listed IMR 4064 load), muzzle blast and reloading cost (19% more powder used per load).
Generally, the reloader has limited choices of powders when loading to get maximum velocity from a particular cartridge/bullet combination. For instance, in the .30-06/180 grain bullet table, there are only three powders listed as achieving 2750 fps MV. These are all relatively inefficient, illustrating the fact that loading for maximum velocity is usually done at the expense of not being able to use the most efficient powders.
It is not for me to criticize shooters who go the maximum power route with any load. I simply want to make it clear that there are tangible tradeoffs when one plays the power card and these tradeoffs are increased when an inherently inefficient powder is used to generate the extra power.
In conclusion, this exercise revealed some things that will inform and guide my reloading strategies in the future. I hope that what I have shared will be useful to others who want to enhance the efficiency of the loads they build and shoot.
Copyright 2018 by Gary Zinn and/or chuckhawks.com. All rights reserved.