fire form, powder choice

[Harpman]

I messed up and sized a bunch of my 45/70 cases, then found out they shoot way better left unsized, So I need to fire them once and dont want to use up my black powder, I have WC860 on hand and red dot, what are your suggestions with these powders just to fire them, accuracy isnt a issue....only need to expand the cases good, soft lead bullets around 8BHN.

[montana_charlie]

I would use them during load development (or practice sessions)...loaded with black.
However, I would use a neck expander plug which opens the mouth to a size very close to what it is after fireforming. That should get your neck tension down close to what you get with unsized cases, and should (might) shoot nearly as well as your preferred loading.
CM

[Hayfield]

I fire form my 45-70 and 40-65 brass without a boolit. 11 grs Unique/.06 card/fill it with grits (dry grits) and compress .250". Gets em about 98% FF'd.

[Jon K]

What Charlie said X2, figure out how much tension you want & get a custom expander from BA or make one. It will shoot good.

Jon

[NickSS]

I have used lots of Red Dot for light plinking loads in a 45-70. Best load is 15 gr and a 300 gr cast bullet. Gives about a 2 to 3 inch group at 100 yards.

[John Boy]

I have WC860 on hand and red dot, what are your suggestions with these powders just to fire them,
Harpman - you want the fastest burn rate powder to fire form cases. Here's the top 10. You have Red Dot. Use it - 10grs and toilet paper though I find Titewad or Bullseye to work better

1. R-1 (Norma)
2. N310 (Vihtavuori)
3. Titewad (Hodgdon)
4. AS- 30N (ADI)
5. Nitro 100 (Accurate)
6. Bullseye (Alliant)
7. Solo 1000 (Accurate)
8. Red Diamond (Scot)
9. AS (Vectan)
10. Red Dot (Alliant)

I just finished FF'ing 100 cases of 348's to 45-75's. Used 15grs of Red Dot because of the thick walls... really didn't do em correctly. So I used 10grs of Titewad and it filled them out nicely.