1873 Carbine Trapdoor loading

[bpetersen]

HI all,

I need to pick your brains a little.

I'm wanting to load a mild plinking load for a new to me 1873 Springfield trapdoor carbine. Made in 1881 for what I can find. I took it to a gunsmith to check it out but I'm not sure how impressed I was with his short look over. Anyway, here are my questions.
1. Is a 405gr. flat base ok for a trapdoor using smokeless? I cast these already.
2. I'm leaning towards 10-12 gr. of Unique. Good, bad or ugly? I have H4895, also. I understand the risk with double loading Unique.
3. Any books with actual load data for Unique using 405gr ? I want to keep the pressure down. Don't want to blow up this antique... or myself...
4. Filler; no filler?
5. Any other thoughts?

Accuracy is secondary. Just want to shoot it some. I am thinking of shooting these out of the 1873 rifle I have first. I am fairly sure it is ok to shoot. My uncle use to shoot, of all things, .410 shotshells out of it from time to time. At least that is what he told me many years ago.

Thanks in advance,
Pete

[M-Tecs]

I love 10 grains of Unique with a 385/405 cast bullet. Your bullet may be undersize for an original. They tend to run .461 to 463" but I have seen larger. I am not a Lee fan but the Lee Hollow Base 405 works very well for TD's

http://castboolits.gunloads.com/showthread.php?190999-My-Trapdoor-Loads-Technique-and-Equipment

http://castboolits.gunloads.com/showthread.php?305281-Trapdoor-carbine-load-with-smokeless-powder

http://castboolits.gunloads.com/showthread.php?153792-Loads-for-old-trapdoor-Springfield

http://castboolits.gunloads.com/showthread.php?321893-Loading-for-a-trapdoor

http://castboolits.gunloads.com/showthread.php?298164-Smokeless-equivalent-load-for-a-Trapdoor

[bpetersen]

Thanks, M-tecs

[Larry Gibson]

As mentioned, TDs run large in the groove diameter compared to modern 45-70 barrels. They were made that way to the prescribed specification. The mould you have will need to cast a bullet not smaller than .459 with a soft alloy (preferably 30-1 or 40-1 lead - tin alloy) . With Unique I wouldn't use a filler or wad of any sort. If your cast bullet does not cast to at least groove diameter then it must obturate to seal the bore (bump up). You will want to use a soft lube such as White Label 50/50 or a BP lube.

I've used 13.5 gr Unique under the Lee 405HB and the Lyman 458124 to duplicate the TD carbine 45-55-405 cartridge's velocity. They run 1100 - 1150 fps out of my carbine. Using just 10 gr Unique would be a very mild load.

[bpetersen]

Larry,
I really appreciate your reply. I am going to just pick up a Hollow Base mold. Seems a no brainer since I cast for my marlin levers.

Pete

[SSGOldfart]

Larry gave you some really great advice above

A book you might want to get is "Loading Cartridges for the Original .45-70 Springfield Rifle and Carbine"by J.S.&Pat Wolf Pat still sells the books and a few other item's I have there phone number if needed pm me.
Check out www.the45-70book.com Wolf's Western Traders.
The third edition is great Spence passed in 1993 but left us some great info.

[Carrier]

Larry,
I really appreciate your reply. I am going to just pick up a Hollow Base mold. Seems a no brainer since I cast for my marlin levers.

Pete

I cast with the Lee HB mold, powder coat them and use 27 grains of H4198. According to Hodgdon this gives 14,200 cup. It’s pretty accurate but I get better accuracy using 60 to 65 grains of Goex FF using the same powder coated bullet with lube.
My Trapdoor is a 1873 made in 1882 and is in very very good condition. Many load higher pressures but I don’t want to take any chances on this one as it’s been in the family since late 1890’s.

[bpetersen]

SSG,
Thanks. I just got the Lyman Cast Bullet book and can't find a thing on using Unique with a 405gr. bullet. I'll have to get the Wolf book.

Carrier,
Thanks for you input.

Pete

[mehavey]

See: https://www.thehighroad.org/index.php?threads/45-70-load-data-for-unique.786275/#post-9993777
Use SOFT(30:1) alloy. It is a lifesaver in adapting slightly smaller bullets to larger bores
50-50 standard lube is fine

[bpetersen]

Thanks, mehavey

Pete

[StrawHat]

A bit of history if I may.

When the carbine was introduced, it did not take long before the lightly built troopers of the day began to mention how the little rifle was beating them up. The powers that be actually heard the troops and decided to find a load that was still powerful and accurate but with less recoil. The first attempt used a cardboard tube in the case and 55 grains of black powder. The headstamp on the cartridge included the latter “C” to distinguish the cartridge from the visually identical rifle cartridge. It worked but the cardboard tube was a pain from the loading aspect. A change was made to used card wars to fill up the space. This also worked but took extra steps to load and mark the headstamp. The final solution was to discard the wadding and seat the bullet down on the powder. This gave a visible difference between rifle and carbine loads and save at least two steps in the loading process.

Kevin