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My brother in-law has a old Springfield trapdoor 45-70 and is hesitant to shoot anything but black powder in it. As far as I know it is in sound shootable condition, so is their any reason a 405 Grain lee hb and a load of trail boss or other lower pressure load should not be fired in the gun?
We shot trail boss out of a 1884 model trapdoor with no issues. Velocity was low.
Quote:
Originally Posted by bigmike13
There is a very common and very mistaken idea that because Trail Boss yields such low velocities it must be a low pressure load, NOT TRUE! Trail Boss can be used for Springfield level loads but there are much better choices that will yield a LOT better velocity at much lower pressures. Check out Hodgdon's data site for Trap Door loads, they have several bullet/powder choices (including TB) for the Trap Door and they show the pressures for these loads. Trail Boss can produce high pressures in these large cases while at the same time producing only very anemic velocities, here are some examples of such taken from Hodgdons own data,
45/70 Trapdoor loads
405 cast bullet they list the max for Trail Boss at a trapdoor load at 13 grains for only 1007 FPS at 25,600 CUP!
Compare that to Varget trap door loads at 1781 at 20,900 CUP or H4895 at 1645 at only 18,900 CUP!
Trail Boss was producing 773 FPS LESS velocity at 4,700 CUP more pressure than Varget and 638 FPS less velocity at 6,700 CUP MORE pressure than H4895!
or how about,
That Trail Boss load to 3031, the same 405 grain cast bullet that Trail Boss pushes to only 1007 FPS at 25,600 CUP will run 1706 FPS at only 21,100 CUP with 3031! The MINIMUM 3031 load using that bullet is going 1597 FPS at only 17,300 CUP! That's 590 FPS more velocity at 8,300 CUP LESS pressure than the same bullet with Trail Boss!
I can't understand why anyone would even consider TB in a large rifle case.
Oldred, thank you for the info, that's a huge help in this project. I have both varget and 3031 so this should be a fun. How much pressure does a 45-70 black powder cartridge yield?
I am not certain of the exact chamber pressures of BP measured in CUP so that it can be compared to Hodgdon's smokeless data but there are many safe smokeless loads that can be used in the Trap Door, in fact have been for many years!
http://data.hodgdon.com/main_menu.asp
http://www.trapdoorcollector.com/shooterstext.html ... Trapdoor Collectors website. Scroll to the bottom and you'll find many smokeless & black powder loading for original Trapdoors
I am using a load from Lyman's 45th edition that was then safe for trapdoors. I am using 14.6 grains of unique behind both the 350 grain and 385 grain (405 grains actual weight with wheel weight alloy) Lyman cast bullet. 1300 and 1250 FPS. Cheap and accurate. I am shooting them in a H&R repro officers model trapdoor. I agree while trail boss works, there are better powders available.
I shoot smokeless loads in my 3 TDs (H&R Officer's Model, LBH Carbine and a M1884 converted into a "Marksman" style target rifle) . The Lee 458-40HB bullet is a good one. I do not agree with Spence wolf that it should be sized down to .459. That bullet always shoots more accurately in original TD barrels if left "as cast" diameter. You might seriously consider getting Spence Wolfs book on replicationg the loads for TDs at http://www.trapdoorcollector.com/shooterstext.html. It is well worth the $s for a TD shooter.
I have pressure tested numerous smokeless powder loads in the 45-70 and find 5744, 3031 and 4895 all work very well under that Lee bullet with a dacron filler. Keep the velocity under 1400 fps and PSIs will be entirely safe and in the realm of BP loads. I found that 1350 fps with the Lee 405HB bullet pretty much regulates it to the M1873 and M1879 rear sight settings.
Larry Gibson