Which Mould For A .50-70 Springfield ?

[Notchy Bob]

Howdy

We have an old .50-70 trapdoor Springfield in the family, although it is not in my personal possession at this time. The rifle is in good shape. I stumbled across a small lot (98 pieces) of new Starline .50-70 brass at very a fair price. The seller said he got the brass in an estate sale. I thought I might try shooting the old Springfield, but I don't think we have a mould for it. I need to rummage around through Dad's old collection of moulds, but I'm not optimistic.

I would like to load some rounds as much like the original service loads as is reasonably possible. If I need to buy a new mould, what would you folks recommend for casting a bullet similar to the original US Government round?

Thank you for your indulgence.

Notchy Bob

[SchuetzenDave]

The Springfield rolling block rifle had a 36:1 twist.
And they shot 450 grain bullets.

BACO JIM512450 480 grain 0.970" Sg=1.80
BACO JIM511500 FN 500 grain 1.010" Sg=1.69

However the Springfield Trapdoor started shooting a 400 grain bullet.
I am not sure of the twist in the Trapdoors.

[George Babits]

The Lyman 515141 is the original government bullet. Weighs about 450 grains. With the slow twist I wouldn't waste any time messing with a heavier/longer bullet. I use the 515141 in several original 50-70s. It is traditional and works very well.

George

[Luke]

Lee 515-450. It drops a bit larger than the Lyman mold, you'll probably need it. But an excellent repro of the original Government bullet.

https://www.midwayusa.com/product/1010205686?pid=434163

[SchuetzenDave]

The 36:1 twist will shoot a heavier bullet so I had a 477 grain bullet made.

The original 450 bullet length is less than twice the bullet diameter.

You have better dynamic stability if the bullet is at least twice the bullet diameter so that is why I made the 477 grain bullet.

[SchuetzenDave]

In the 36:1 twist barrel a 1.15" long bullet will have a gyroscopic stability factor of 1.4 or less which means it is not rotating fast enough to stabilize.
My 477 grain bullet 1.034" long is over twice the bullet diameter and is still short enough to gyroscopically stabilize.
The longer length also moves the center of gravity a bit further forward which enables much better dynamic stability for longer range shooting.

Caliber 0.508 Inches
Bullet Weight 477 Grains
Bullet Length 1.034 Inches
Barrel Twist 36 Inches/turn
muzzle velocity 1250 fps
Temperature 50 degrees Fahrenheit (59 is standard)
Pressure 29.92 inches of mercury (29.92 is standard)

Sg = 1.56

[SchuetzenDave]

In the 36:1 twist barrel a 1.15" long bullet will have a gyroscopic stability factor of 1.4 or less which means it is not rotating fast enough to stabilize.
My 477 grain bullet 1.034" long is over twice the bullet diameter and is still short enough to gyroscopically stabilize.
The longer length also moves the center of gravity a bit further forward which enables much better dynamic stability for longer range shooting.

Caliber 0.515 Inches
Bullet Weight 477 Grains
Bullet Length 1.034 Inches
Barrel Twist 36 Inches/turn
muzzle velocity 1250 fps
Temperature 50 degrees Fahrenheit (59 is standard)
Pressure 29.92 inches of mercury (29.92 is standard)

Sg = 1.59

[Woody]

The Lyman 515141 is the original government bullet. Weighs about 450 grains. With the slow twist I wouldn't waste any time messing with a heavier/longer bullet. I use the 515141 in several original 50-70s. It is traditional and works very well.

George

I agree. Been shooting it since the seventy's in both an original 1869 Springfield Trapdoor and Sharps conversion carbine. Works extremely well in both. Still have the Sharps, but the Springfield went to a new home.

Woody

[marlinman93]

I wouldn't get any mold until the gun is in your hands and you can slug the bore to know what diameter bullet it needs.

[Luke]

FWIW the Springfield 50-70s have a 1-42 twist. The classic gov't bullet at 0.97 to 1.0 inch is as long as you want to go.

I personally do not like the current 515141. It drops too small in diameter for many trapdoor barrels, and somewhere along the line Lyman changed the lube grooves from square to round, I have an older Ideal 141 mold and it's far better. Lee gets it right in this case.

[SchuetzenDave]

If the rifle has a 42:1 twist then the 450 grain bullet is too long (Sg only 1.37 and you need an Sg of at least 1.40).

Insufficient twist to get minimum spin on the bullet.

The earlier trapdoors that had a 42:1 twist shot 400 grain bullets.

The later versions had 36:1 twist and shot the 450 grain bullet is what I was advised.

Caliber 0.515 Inches
Bullet Weight 450 Grains
Bullet Length 0.95 Inches
Barrel Twist 42 Inches/turn
muzzle velocity 1250 fps
Temperature 50 degrees Fahrenheit (59 is standard)
Pressure 29.92 inches of mercury (29.92 is standard)

Sg = 1.37

[Luke]

No, they were all 42-1. The Goverment only loaded one bullet in the 50-70, the 450 grain conical. There were some short case carbine loads for other arms, but they used a 350 grain conical. The sleeved Sharps conversion carbines used a tighter twist, but the infantry rifles never changed. The bullet was stable to 300 paces, and that was all they cared about UNTIL the Franco Prussian war showed long range volley fire could be effective, but by that time Springfield was beginning work on the 42-45 caliber chamberings, so no change was made to the older tooling. I believe the Remingtons sold to the NY State troops and some others had the tighter twist, but not the Gov't Trapdoors.

Thus the 50 1 3/4" had a reputation for indifferent accuracy only recently dispelled.

[George Babits]

One of my 50-70s is a really nice 1870 Springfield USN. I think they used the same barrel and sights as the 1868 trapdoor. It really shoots good with the 450 grain Lyman 515141. My Farmingdale Shiloh infantry rifle also does very well with that bullet. If I remember right it has a 1:36 twist. I haven't measured the twist in my original Sharps carbine, but would guess that the twist is the same as the 1868 since the sleeves were produced by Springfield. I've been using the 450 grain bullet in that too, but hope to experiment with a 350 grain bullet in the carbine this summer, mainly to reduce the recoil.

George

[bobw]

Sure glad I shoot paper patch bullets in my 50-70 shiloh so I can adj the weight with the mold as needed. But carry on with your mid winter word brawl by all means. Bobw

[mike herth]

That’s interesting Bob. What is the ROT and what length is the bullet that works best for you? I’ve been thinking of a PP mold for my Roller 50-70 that has a 24:1 ROT. And are you using a KAL adjustable mold?