Reaching further with the Trapdoor, suggestions?

[flintlocke]

I developed a good load for the trapdoor cadet at 100 yds., thanks to Larry Gibson. Now I'd like to work out to 600, with a minimum of trial and error firing. Moving a target out in 100 yard increments establishing range dope as you go is VERY time consuming, and increasing weather variables as the day wears on. I want to do a little doping ahead of time with ballistic programs to try to shorten the process. So, I need to estimate a b.c. for my bullet. Now please don't poke fun, my bullet is the Lee 405 gr hollow base, for which I can not find a published b.c. Closest seems to be a Lyman flat base 457193 405 gr, in Cast Bullets 4th Ed they show that bullet at .307 b.c. Those numbers could work, maybe, but I know less than nothing about the effect of the hollow base on b.c....if any. Suggestions ?

[Carrier]

I’ve been looking at trying to reach out further with my Trapdoor though these old eyes and that small sight may have something to say about it. However all my research has led to using a 500 grain or larger bullet. The Lee 405 HB has worked very well for me out to 200 yards.
I would look up what Larry Gibson, Indian Joe and others have written about what works and doesn’t. It’s too bad Lee wouldn’t have made the 500 grain bullet 359-500-3R with a much rounder nose than what it is as it has worked well for me out to 200 yards but like others here have said it craps out further because of its long pointed nose.

[flintlocke]

Yeah, no doubt the nearly original 500 gr is the better bullet for longer ranges, only reason I went with the 405 hollow base is that my groove dia. is about .463, and the el cheapo Lee hollow base gave me the accuracy I was looking for, without going out and buying expensive molds, just to see if they would work. Once I find out what my rifle is capable of, I don't mind spending the money.
By the way, my Cadet is not collector quality by a long shot, so I didn't feel too bad about squaring and widening the rear leaf notch and installing a square post "1903" sight on the front. Made a world of difference on target. I'm 74 and I think I wore out my eyes looking through them, who'da thunk it?

[Larry Gibson]

Which rear sight do you have on your TD; M1873, M1879 or M1884?

What velocity is your load out of your Cadet?

[flintlocke]

1884 Buffington? 1354 fps taken 15 ft from the muzzle.

[DeadWoodDan]

Watching/Subscribed to this thread as I have been away shooting and loading for the 17 & 20 cals. My trapdoor is the last rifle I left working on.

[country gent]

If you have access to a lab radar run a few rounds over it and get velocities at muzzle and 100-200 yds. With this you can use programs on line to actually figure the bc of your bullet and then very accurate drop tables. You can use other chronographs but then have to chrono at 2 ranges.

[Winger Ed.]

It's all about the rear sight, and knowing the drop at what range.

In a article I'd read about when the Army was testing it prior to adoption not too long after the Civil War,
A Major in the Ordnance dept. was firing on a 6' square target at 1,000 yards and hitting it consistently.

The idea was to determine if it could take a man off a horse at that range.

[Larry Gibson]

flintlocke

Instead of trying to dope a trajectory for your rifle why not use the range regulation on the rear sight?

Do you know how to use the rear sight, especially the aperture sight? If your Buffington rear sight leaf has an "R" stamped on the upper right part of the leaf it is regulated for the M1888 cartridge with a 500 gr bullet at 1250 fps +/-. The lowest sight setting will be for 150 yards with the 500 gr bullet so the M1873 (the lee bullet) bullet should be hitting higher at 8 - 12" at 100 yards (?) if you've not replaced the front sight blade with a taller one? The M1873 load (yours replicates it) will hit 2 -3 moa higher than the M1888 load. At any rate with the slide aperture rand set at 150 (the lowest setting) and you know where your load hits at 100 yards then adjust the slide to the 600 yards setting and shoot at 600 yards. You should be close....close enough to make/tweak the rear sight setting so POI is where you want it. Where the horizontal aperture line is ends up in relation to the "6" will give you a close point to set it in relation to the other ranges. Example: say the horizontal line looks to be set close to 575 yards on the leaf. Then for a 500 yard target set the aperture horizontal line on 475 yards. You'll be amazed at how close the shooting results can be.

[KCSO]

You shoulf see if you can get a copy of Army of Marksman by Christiansen. This covers what the Army did to reach out with the Trapdoor and will save you a lot of time and trouble. Now to start you will want a 300 grain bullet as long range is why they dropped the 405. With the 500 the range markings will be close on the gun with Black Powder loads. My load is 62 grains of FFg Schuetzen and a 500 grqin bullet lubed with bear oil and bees wax with a magnum /rifle primer. Light compression just firm on the powder.