Help Bullet Stabilization (45/70)

[wolves63]

I am unsure of what I need to do for bullet stabilization for my 45/70.

Current load specs:
Powder Load: Hodgdon Varget 50.5 1,655 18,600 CUP
Estimated Velocity: 1670 (do not have a chronograph yet)
Bullet Weight: 405 grain FN that is powder coated

I am getting significant tumbling. I am shooting it through a Henry Lever Action H010B.

Any initial suggestions would be perfect.

[Bird]

What is the firearm? What is your bullet diameter? What is the bullet?

[smithnframe]

What is the twist rate of the barrel?

[RedlegEd]

Hi. A couple of questions first.
1. Have you slugged the barrel? If it's a newer Henry, it should have a 1:20" twist.
2. Did you get the same results with lower velocity loads?
3. What is the length and diameter of the PC'd bullets? What alloy?
4. What kind of expander die are you using?

Here's why I'm asking. The 1:20 twist should stabilize a 405 grain bullet just fine (the trapdoor has a 1:22 twist,) so I don't think the twist of the barrel is an issue, though 1670fps is a bit fast. That points to a possible fit issue. Your bullet should be cast/sized to fit the groove diameter +.001/.002. A smaller size may cause leading and/or stabilization issues. As an example, my son had horrible tumbling problems shooting a 400gr Saeco Spitzer from his SOCOM. We walked back the problem and found he had inadvertently sized them to .452 using the wrong push through Lee sizer [head smack!] Additionally, if you aren't expanding your cases sufficiently (not just belling the mouth,) you could be swaging down the diameter depending how soft your alloy is. If the diameter of the bullets you are loading is .459 or .460, then go ahead and pull a bullet from a round already loaded and check the diameter. If it's at or below 0.458, I think you'll need to get an expander die. NOE makes good ones that will fit into a Lee Universal expander die body (http://noebulletmolds.com/NV/product_info.php?cPath=565_88&products_id=1521). Ideally, you'll only need 0.001 to 0.002 case tension on your bullet.
Hope this helps. Ed