As I still go through the process of getting the components needed for 45-70 BP loads Im a little stuck. 

Or rather, Id rather ask than guess.

I have a role of vegetable wad; 3 ft roll, that I was going to punch to use for the 45-70.

The questions is on compression of BP.

Other than the obvious of getting the air pockets out of the powder column, I read that people experiment with different compression depth. Is that in relation to the size of the bullet or is that another tool used in fine tuning a load? As for instance testing different OAL's to see if it tightens up groups?


As far as the vegetable wads; what is reason for different thicknesses?

Personal preference or specific need per load

Not a BP expert, but OAL does affect accuracy, but it's not the reason for a certain amount of compression. And wad thickness is based on getting the compression you want without having to resort to more or less powder.
It's a matter of experimenting with the cartridge, bullet, OAL, and how the bullet fits the lead in your barrel. Only thing for certain is you can try different amounts of compression, and amount of powder to see what your gun likes best, and adjust wad thickness to optimize the loading.
You'll likely end up with a wad .030"-.060" thickness. And compression of either very little, to maybe 1/4" compression. It depends on the powder, and what your gun shoots best.
Here's a very good primer that will hopefully get you started, and answer some questions.

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OK, thanks for the info and links. It is starting to make more sense to me now.

One question I have is with what Ive been reading when people say " dont compress powder with bullet"

As a hypothetical, lets say I have 68 gr by weight of 2f brand X. I put a .030 wad over it and initially start with no compression but the bullet, to fit, compresses the wad and powder column?

Isnt that something that would happen?

Or is it meant to say bullet directly against powder without wad?

It really is quite simple - if you use the (soft lead) bullet to compress the powder, it will deform - sometimes op to the point thqt you won't be able to chamber it, and anyway, it won't be good for your accuracy.
So what you want is to avoid deforming the bullet because you're compressing the powder.  No compression means the base of the bullet will  barely 'kiss' the overpowder wad when seating the bullet.
But if you're looking into some serious compression, that's where the compression die comes in.

Dave, let's start at the other end. I think most will drop a bullet into the chamber and measure the distance from the base of the bullet to the breech end of the barrel. Then, one way would be to add the length of the bullet to that distance and you have your OAL. You can then figure out the distance the bullet is seated in the case. The compression die is set to the seating depth of the bullet. If you fill the case with powder to that depth you have zero compression with no wad. Subtract the thickness of the wad (say .060) from the depth of the powder and you have zero compression with the wad. The amount of powder in the case at that point can vary depending on how you get the powder into the case. A straight dump into the case will give you the least amount of powder. Using drop tubes of various lengths and various techniques of putting the powder into the drop tube funnel will allow some increases in the amount of powder you can have still at zero compression. From whatever that point is, adding more powder will require compression with the compression die to maintain the bullet seating depth. All these things are related so changing one thing makes changes to everything else. I probably wouldn't worry about changing the bullet seating depth until you have everything else under control (including changing primers and perhaps adding an underpowder/over primer wad).

oneatatime wrote on Nov 9^th, 2020 at 12:26pm:




Ok this is starting to click

So what I planned on starting with is this:

GOEX Olde Eynsford 2f by weight
67
68
69

Montana Bullet LBT, 535GR, POSTELL

.060 Wad

Im guessing Im going to need some compression so I will start with minimum about to seat after finding my OAL using your formula.

I guess from there I will just see what the rifle likes and tune from there before messing with compression and then eventually adjusting components.

Does this sound like the route to start?

marlinguy wrote on Nov 9^th, 2020 at 7:54pm:




Will do, I actually just added the die to my list of stuff to order just to make it easier