Reduced 308 Winchester loads with TRAIL BOSS!

I’ve been on a reduced-load kick lately. This is a big change from my earlier (and younger) days of reloading. No longer trying to get the most speed out of a cartridge, I’ve come to appreciate the light impulse of reduced rounds. Even better, some of the loads have proven to be surprisingly accurate. If you like your reloads fast and loud, I apologize in advance, this post isn’t for you.

Most of my reduced-recoil load work to date has been with H4895, which is, according to Hodgdon, the slowest powder they have that you can safely reduce loads with. With the 308 Winchester paired with the 150 Pro-Hunter and 168 SMK, I was able to make loads that had a muzzle velocity of approximately 60% of the full power charge (1,933 feet/second for the 150 and 1,856 feet/second for the 168), but it is possible to go even slower and lighter safely, with another powder, Trail Boss.

WARNING: The loads shown are for informational purposes only. They are only safe in the rifle shown and may not be safe in yours. Consult appropriate load manuals prior to developing your own handloads. Rifleshooter.com and its authors, do not assume any responsibility, directly or indirectly for the safety of the readers attempting to follow any instructions or perform any of the tasks shown, or the use or misuse of any information contained herein, on this website.

According to Hodgdon:

“Trail Boss was designed primarily for reduced loads using lead bullets in pistol cartridges. However, Trail Boss offers superb versatility in rifle cartridges producing reduced loads using lead or jacketed bullets. These reduced loads make firing such cartridges as the 300 Winchester Magnum or even the 458 Winchester Magnum pure fun!

Listed below we show a few examples of such loads throughout the Reloading Data Center, but the fun doesn’t stop there. If you don’t see Trail Boss data for your favorite cartridge we have a formula for developing loads for all cartridges and it’s simple to follow.

This formula may be used in both rifle and pistol applications: Find where the base of the bullet to be loaded is located in the case and make a mark on the outside of the case at this location. Then fill the case to that mark with Trail Boss, pour into the scale pan and weigh. This is your maximum load. Pressures will be below the maximum allowed for this cartridge and perfectly safe to use! Take 70% of this powder charge weight (multiply the maximum load from step 1 by .7), and that is your starting load. Start with this beginning load and work up to your maximum charge, all the while searching for the most accurate reduced load. Once found, the fun begins!”

The literature was pretty impressive. I reached out directly to Hodgdon with a few questions about the powder itself and this is what I found out.

“Trail Boss is different from other powders due to its amazing, low bulk density. Few powders come anywhere near the 325 g/L bulk density of Trail Boss. By giving the powder such a “fluffy” measure, it utilizes most of the capacity of almost any case chosen. In normal cartridge loading, full cases generally provide the most uniformity and accuracy. It holds true here. When one loads a full case with this powder, he needs to refrain from any compression. Compression affects the ignition of this powder, causing less uniform velocities and lesser accuracy. We maintain excellent results from 100% loading density, down to 70 % loading density. One can find his load somewhere in that range. In all small arms cartridges, from the Hornet up to the 460 Weatherby magnum, you cannot exceed maximum pressures with 100% load density loadings. No other powder can claim that distinction.

Because of its bulk density and porosity, it lights easily, contributing to uniform velocities and pressures, and of course, excellent accuracy. With Trail Boss, big cartridges become fun to shoot for practice!”

Wow. Things are getting really interesting now. For comparison purposes, Varget has a density of 925 g/L, nearly 3X that of Trail Boss.

FOR MORE INFORMATION ABOUT TRAIL BOSS LOADS, CLICK HERE

Seems pretty interesting doesn’t it. In many ways this is the antithesis of the reloading protocols I’ve been following for the past two decades! I couldn’t wait to give Trail Boss a try!

Reduced loads could be beneficial because they allow for:

Less recoil for young shooters. You can download a rifle for a young shooter to kick less with less muzzle blast. Get a lightweight 308 Winchester hunting rifle, download it, and as your kid grows, change over to full power loads. Maybe it is a better option than the horrific blast associated with muzzle brakes?
Less mirage than full power loads. For shorter range shooting, you can fire more rounds before you pick up mirage from the barrel. I fired the 50 rounds shot in this post in about 20 minutes with no noticeable barrel mirage- impressive!
Short range plinking. The reduced loads run cooler. If you are shooting varmints or plinking at closer ranges, the reduced loads will be easier on your gear.
Practice from alternate positions, especially with lightweight hunting rifles. If you shoot heavy guns and pick up a hunting rifle, you know how much more they beat you up. With reduced recoil loads, a hunter could work on offhand, positional, and field expedient shooting positions at short to moderate ranges with his actual hunting rifle without worrying about developing a flinch.

This is the rifle that I used for testing and evaluation, my trusty old olive drab 308. This customized Remington 700 has been used in posts for years. The rifle contains the following parts from Brownells:

The stock shown in the image is a Konohawk K2. The rifle switches back and fourth between the Konohawk and a McMillan A5. Glass is a Schmidt and Bender 5-45×56 PMII.

If you go to Hodgdon’s website, you’ll find two technical documents about reduced loads for rifles, one related to H4895 and the other Trail Boss(a bulky powder that safely makes even lighter loads).

I decided to work with my trusty 308 Winchester. I selected this gun primarily because I had just used it for my H4895 reduced-recoil load post. Plus, by using the same two bullets, the Sierra 150 Pro-Hunter and 168 MatchKing, I am able to make direct comparisons between reduced loads using H4895 and Trail Boss.

Measuring Trail Boss can be tricky, it doesn’t meter particularly well (it looks like a bunch of flat donuts), so I used an RCBS Charge Master to measure my loads. For each bullet, I settled on a overall length of 2.810″.

The table below shows the results. Note the column “CPOI”, this denotes the change in point of impact from a 100 yard zero in inches, rounded to the nearest half inch. Depending on the load used, the bullet can drop anywhere from 2.5 to 12.5 inches

All rounds were fired prone, from a bipod with a rear bag. Muzzle velocity was recorded with a MagnetoSpeed V3 barrel mounted ballistic chronograph.

For the 150 Pro-Hunter, velocities ranged from 1,164 to 1,476 feet/second while the 168 SMK velocities ranged from 1,084 to 1,412 feet/second! These loads are significantly slower than even the 60% H4895 loads I developed with the same bullets in the same rifle- 1,933 feet/second for the 150 Pro-Hunter and 1,856 feet/second for the 168 SMK. (Note the two lowest velocity groups with the 168 SMK didn’t stabilize the bullet at 100 yards, more on this later…)

Unlike the reduced power H4895 loads, which in both the 6.5 Creedmoor and 308 Winchester had similar points of impact (POI) to their full power counterparts, the Trail Boss loads all had a POI at 100 yards that was lower than the full power equivalent. The image above shows an arrow indicating the point of aim (POA) and POI for each of the groups shown. The change in POI ranged from -12.5 to -2.5″ depending on the load (these values were rounded to the nearest 1/2 inch).

Also note the heaviest charge (14.0 grains) in each cartridge also resulted in a larger groups than the more moderate loads. This may be the result of minor compression which in turn could lead to less consistent ignition as mentioned by Hodgdon IMR earlier.

I did manage to produce some fairly impressive 100 yard groups. The 13.0 gr 150 Pro-Hunter put 4 shots into .608″ (.581 MOA) while the 168 SMK managed 5-shot groups measuring .750″ (.716 MOA) and .898″ (.858 MOA) with 12.0 and 13.0 grains of Trail Boss respectively.

Perhaps the highlight of my trip were the two groups I shot with tumbling bullets. The 168 SMK wasn’t stabilized at 100 yards with the 10.0 and 11.0 grain Trail Boss loads, however, they each produced a 5-shot group of 2.073″ (2.149 MOA) and 1.286″ (1.228 MOA) respectively! Check out the group above, nearly 1 MOA with tumbling bullets! Who would have thought that was possible!

If you are a reloader and haven’t tried shooting some reduced loads with either Trail Boss or H4895 you are missing out. Besides the “legitimate” uses I mentioned in the beginning of the post, shooting reduced loads is just plain fun. With over two decades behind a rifle, it is the little things that make this sport more enjoyable. My reduced loads are certainly one of those things. Besides, if you have a 460 Weatherby Magnum sitting in the safe that you are leery of shooting, you might as well break it out with some Trail Boss. I guarantee you’ll enjoy shooting it more and you’ll have a smile on your face!

To learn more about loading with Trail Boss, visit the Trail Boss reloading data page here.

To buy Trail Boss, reloading equipment or build a rifle, please check out Brownells. They help keep the lights on!