Obturation on cast boolits. Trapdoor 45-70

[TheFlynn01]

Hey there folks, was curious about this and wanted to get my head wrapped around it. I recently have acquired a trapdoor 1884 Springfield. I want to do some good shooting with it, and I got the book by Wolf. There is a lot of info in there and I got a the Lee mold he recommended for the 500 Grain flat base bullet. the Lee90577 for those interested. He does recommend others but that one is the most economical to me at the moment.

Now I currently only have access to an indoor range, so I will have to make up smokeless loads to try this thing out. I got some good material made up for the 20-1 lead to tin as he suggests. I am curious to see if these will shoot well, or if the bullet will not obturate properly because it is smokless rather than black powder? Open to advice on how to get some well shooting rounds out of this old rifle.

Thanks for taking the time!

[Larry Gibson]

Spence was replicating 1873 sevice loads which did depend on obturation. However, better results can be had with TDs by not depending on Obturation. Have you read my posts in?

https://castboolits.gunloads.com/sho...-and-Equipment

[BLAHUT]

soft lead - over size bullets

[badwolf]

I like the 405 lee hollow base bullet and the carbine load in Spence's book

[Gtek]

May I suggest that finding your internal dimensions step one and moving on from there might get you to a success story a little faster. I must ask, you would not touch one BP load off at the indoor just for effect?

[steveu]

I have found.460-461” works best for me. 20-1 shot ok, now using isotope lead.

[Rockindaddy]

Hollow base Lee 45-70 mould sized to .461 soft lead 1-20 works in my 73 Trapdoor Cadet rifle and 1873 Trapdoor carbine. The Springfield 1873 Trapdoor barrels have very deep .462 groove diameters. 25grs of IMR4759 works well too! Also 25grs of 5744 shoots tight groups. I don't shoot black powder in my old metallic cartridge rifles. Hate scrubbing the fired cases and fouled bores.

[Green Frog]

If you're just starting out with reloading, you can disregard Rockindaddy's suggestion to use 4759, it's been discontinued for several years now and even if you could find a pound to experiment with, you'd use it up when you were starting to really do well with it and get frustrated trying to find more. Since similar amounts of 5744 do well for him, and it's still available (I think).

I say this as one who used 4759 in my 45-70 high walls, but that was 30 years ago and it was widely available back then. I loved this powder when it was being sold, but you'd be flogging a deceased equine to try to use it now!

Froggie

[Good Cheer]

Mine was dated 1889 and had a grossly oversized groove diameter.
You couldn't chamber a round loaded with a fat enough bullet.
Going off of memory the loads I used were #457125 of almost straight lead and Unique to fill the grooves.

[ascast]

Unique works OK, start at 8 grns and go up. 462" dia is also a good place to start. rad Larry G's peice.

[TheFlynn01]

Spence was replicating 1873 sevice loads which did depend on obturation. However, better results can be had with TDs by not depending on Obturation. Have you read my posts in?

https://castboolits.gunloads.com/sho...-and-Equipment

I have not, I am reading though it now. Alot of good info in here, thank you

[TheFlynn01]

If you're just starting out with reloading, you can disregard Rockindaddy's suggestion to use 4759, it's been discontinued for several years now and even if you could find a pound to experiment with, you'd use it up when you were starting to really do well with it and get frustrated trying to find more. Since similar amounts of 5744 do well for him, and it's still available (I think).

I say this as one who used 4759 in my 45-70 high walls, but that was 30 years ago and it was widely available back then. I loved this powder when it was being sold, but you'd be flogging a deceased equine to try to use it now!

Froggie

Well I do have some 5744 so I will start with that. I heard its good for BP cartages!

[Castaway]

steveu, I know what an isotope is and lead has four of them (stable). Which isotope? Exactly what do you mean?

[dondiego]

steveu, I know what an isotope is and lead has four of them (stable). Which isotope? Exactly what do you mean?

I am thinking that he means the lead containers that medical isotopes come in.

[TD1886]

Spence was replicating 1873 sevice loads which did depend on obturation. However, better results can be had with TDs by not depending on Obturation. Have you read my posts in?

https://castboolits.gunloads.com/sho...-and-Equipment

I'm sure this has been done, but has anyone check their groove diameter and then see what is the fattest cast bullet they can load and chamber and perhaps it may be larger then the groove? I don't own a TD and wish I did, but I have an 1886 and that is what I had to do with my rifle.

[Sgt H]

You can get a pretty good idea of how fat a bullet you can load and still chamber the round. Measure the inside diameter of the neck from a case fired in your rifle. Cases usually contract about .001" after firing and this should give you the max diameter usable. In some cases this still may not be as large as the groove diameter on a trapdoor or so I have heard. That said you can still get soft boolits to obturate with faster smokeless powders. I would suggest nothing slower than 2400 or 5744.

[steveu]

I am thinking that he means the lead containers that medical isotopes come in.

That is correct! It has some antimony. Got some for 50 cents a pound before Covid. Has a bhn around 11.5.

[TheFlynn01]

You can get a pretty good idea of how fat a bullet you can load and still chamber the round. Measure the inside diameter of the neck from a case fired in your rifle. Cases usually contract about .001" after firing and this should give you the max diameter usable. In some cases this still may not be as large as the groove diameter on a trapdoor or so I have heard. That said you can still get soft boolits to obturate with faster smokeless powders. I would suggest nothing slower than 2400 or 5744.

So would that be better than slugging the bore? I heard that the trap doors can be weird for finding the right size because of the three groves.


Also curious on what molds you all might recommend. Reading through Larry's post... It seems some of those molds are hard to find. The Lee molds seem to drop them at around .459 but I am wondering if that is too small for the old trapdoors. Would any of the NOE molds serve well? Just wanting opinions to kick around.

[firefly1957]

My model 1884 was made in 1889 like someone stated above it has a large groove diameter . The groove depth of my gun is .461" I bought the Lee 405 grain .459" hollow base mold it casts at .461" and I pan lube it and shoot it as is . I use two loads in the old gun 55 grains of FG and a charge from a old Hercules booklet for RE-7 todays RE-7 is not the same powder so that information is no longer any good . Both loads should give me about 1150 f/s and the load of Reloader 7 has taken my largest buck yet .

The barrel of my gun was cut down somewhere over the years and does have some bad pits but shoots quite well enough at the lower speed .

[TheFlynn01]

My model 1884 was made in 1889 like someone stated above it has a large groove diameter . The groove depth of my gun is .461" I bought the Lee 405 grain .459" hollow base mold it casts at .461" and I pan lube it and shoot it as is . I use two loads in the old gun 55 grains of FG and a charge from a old Hercules booklet for RE-7 todays RE-7 is not the same powder so that information is no longer any good . Both loads should give me about 1150 f/s and the load of Reloader 7 has taken my largest buck yet .

The barrel of my gun was cut down somewhere over the years and does have some bad pits but shoots quite well enough at the lower speed .

Well thats good to know. I got the hollow point lee and the 500 grain flatbottom lee. So we will see how they drop, and then see how they shoot. I do wanna find a good round nose 500 grain mold. I like that classic look.