IMR Trail Boss Powder with Jacketed Bullets
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Thread: IMR Trail Boss Powder with Jacketed Bullets

  1. #1
    Join Date
    Sep 2007
    near Houston, Tx

    Default IMR Trail Boss Powder with Jacketed Bullets

    Thought I'd post info on using the IMR Trail Boss with jacketed bullets that was in an article in the new 2010 Hodgdon Reloading Manual/Magazine, beginning on page 50. By the way this manual has a problem, page 108 and 109 are reversed, be careful when looking at 7mm cartridge load data in it.

    When IMR introduced the Trail Boss powder it was described as being for cowboy shooting, using trail boss only with cast bullets in straight wall type brass. Using it in bottleneck cartridges with cast bullets was unsafe. I was told this by someone at IMR when I called them, seeking trail boss load data for cast bullets in 308 or 30-06 ammo. Basically I was told by IMR the powder had some unique burn properties making it unsuitable for bottleneck cartridges. About a year later after phone call to IMR, article appeared in a gun magazine about using Trail Boss in bottleneck cartridges with cast bullets and later Hodgdon (after taking over IMR I think), began showing bottleneck cartridge loads with cast bullets on their website.

    Now, in the new 2010 Hodgdon reloading manual, their article says you cannot put enough Trail Boss in a bottleneck case to cause an overcharge problem. They now recommend this method with the powder for using jacketed bullets for reduced loads.

    Seat a bullet in brass, mark brass where bottom of bullet is. Pull bullet and fill case with trail boss to the line you have marked for bottom of bullet. Then measure the grains of powder it took to reach mark. This number of grains of Trail Boss you've measured is the 100% load density. Article said you should start your reloads at 70% load density. For example: if a 270 Winchester brass takes 20 grains of trail boss for 100% load density with jacketed bullet you want to use, then multiply 20gr by .70, which gives you the 14 grains, the 70% load density. (20 gr X .70 = 14 grs, the 70% load density) ( 20 gr X .80 = 16gr, the 80 percent load density). Article says to increase charge in 5 grain increments to find trail boss load with best accuracy for jacketed bullet you are using. Optimum accuracy should be between 70 to 100% load density.

    As I said earlier, the article states, "it is impossible to overcharge any cartridge with Trail Boss, simply because it is impossible to get enough into a case to exceed maximum chamber pressures for that cartridge."

  2. #2
    Join Date
    Dec 1969
    Anchorage, AK


    Interesting concept... Wouldn't it be neat if all you had to do was scoop enough powder into the case for 100% load density, seat a bullet, and then have accurate loads? LOL yeah and use bullets cast from Wheel weights, unsized, and tumble lubed too! Woo hooo

    NAH that's wish full thinking.......
    Benefactor Life Member, NRA
    Life Member, Alaska Gun Collectors Association
    Life member, VFW
    Anchorage, AK

    "Remember the Range day, And keep it holy. May the light of the Holy Tracer guide thy aim"

  3. #3
    Join Date
    Dec 1969


    I used some Trail Boss in cast British .303 reloading today. Did the quick numbers last night and whipped up four sets of 5 cartridges all with 185 gr cast lead bullets. Used the four Lee powder scoups 2.2, 2.5, 2.8, and 3.1 cc which is about 10.6, 11.7, 13.2, and 14.6 gr of TB resp.
    Shot at 50 m. out of a 1916 BSA SMLE.
    The lowest charge grouped best but was like 14 inches low. Middle charges were pretty wild, 2nd lowest especially. Highest charge was 2nd best group but was also back to around 2 inches low vs POA.
    I do believe I'll continue and try and develop a 95% +/- charge.
    I am encouraged.
    BTW I tried 'the Load' [13.0 gr Red Dot] with this bullet and gun before and while the bullets hit near POA and grouped OK they almost always keyholed. None of the shots today with TB keyholed.
    Update: Tried the heavier charge .303 loads today and that didn't pan out, groups were poor. In the meantime I whipped up some 7.5x54 French with Trail Boss too and again the lighter loads were more accurate. It is the range Trail Boss was designed for, that is, slower lead bullets. I don't like jacking the sights so high hence the 95% attempt but I guess the large drop goes with the territory.
    Last edited by Lars; 02-20-2010 at 11:42 PM. Reason: update
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