45-70, how much compression?

[Tatume]

Hello Folks,

Again, as a muzzle loading rifle shooter, I don't have much of a feel for how much compression to employ when loading black powder in the 45-70 cartridge. I'll be using Starline cases, and will start off with the Lee 405 gr plain based bullet. From what I've read, only the old balloon-head cases would actually accept 70 gr of powder, but that may have been with a 500 gr bullet. It was also probably FFg granulation; I'll be using FFFg (that's what I have). My inclination is to load a case up to where the bullet base will just touch the powder, then add a grain or two.

Thanks for the advice.

Take care, Tom

['74 sharps]

Using a compression die rather than the bullet is the best way to compress the powder. The bullet may deform. Different powders, according to forum posts, work better with different compression. It is possible to get 70+grains in a case; however, may not be the best avenue for accuracy.

[littlejack]

Hey Tom:
Your Starline brass will be thick, as compared to Winchester or Remington.
I use Winchester, and have no trouble at all getting 70 grains of ffg in my cases. With that being said, you will be able to get the 70 grains in your cases, but you may have to compress more. The fffg powder that you are using will probably help you with the charge weight.
I do use a short drop tube and vibrate as I drop the powder in my case.
I use a .040 card wad on top of the powder, compress about .125, then seat the boolit to just set on the wad. I load the Lyman government 457125 boolit with one gg set out of the case. The lands just hug the first driving band.
I tried the fffg powder, but got better accuracy with the ffg. I use Goex powder.
Hope this helps.
Jack

[Seth Hawkins]

You can get more than 70 grains of any grade in the case. The problem you'll need to address is this - how far out of the case can you seat the bullet, and still get it to chamber completely? Compressing the powder will, of course, allow you to seat the bullet deeper into the case. But there's a limit as to how much you can compress the powder.

My .45-70 load consists of 70 grains of Swiss 1.5Fg that's very lightly compressed, with a Lyman 457677 tapered bullet. The tapered bullet allows me to have less of it in the case, and more powder in the case, with practically no compression. This is a fairly accurate load in my rifle.

[Grapeshot]

There are several schools of thought on this. Spence Wolf, in his book on reloading the .45-70 for the trapdoor rifles and carbines, stated that to allow the 500 grain bullet to be seated to the correct depth in the Winchester case, the 70 grains of BP was compressed .600 inch using a compression die to. That is a lot of compression and he also stated that to get the best ignition he used a Winchester or Federal Large Rifle Magnum Primers.

Paul Matthews took a similar approach in his books "Forty Years with the .45-70, and "The Paper Jacket".

I would glean all I could off this forum and then go and find these books and read them before making any decisions on compressing BP.

[montana_charlie]

Hello Folks,

Again, as a muzzle loading rifle shooter, I don't have much of a feel for how much compression to employ when loading black powder in the 45-70 cartridge.
There are two reasons for compressing the black powder.
- Compress in order to get a more efficient burn ... with less fouling.
- Compress so that more powder can be loaded under the bullet ... to increase muzzle velocity.

Some brands of powder are sensitive to the first reason, Goex being one of them.
To find a 'good load' with Goex, start as you intend to ... with just a bit more powder than it takes to fill the case to the bullet's base.

If fouling seems especially heavy, add a grain of powder, compress it to the same depth as used earlier, and try again.

After you have gone through all of the 'reasonable' amounts of powder in that case size, you will have a feel for which amount of powder (and how much compression) seems most efficient.

At some point in that journey, you will also have seen your best accuracy.

In an ideal world, the efficient burn and the smallest group happened with the same load.

CM

[Seth Hawkins]

CM - I'm going thru this process now with my Shiloh .44-77 with Goex and PP loads. Going from about 0.15" compression of 70 grains of FFg to about 0.25" compression of 70 grains of FFg produced a lot more fouling, and forced me to raise my sights 20 minutes at 100 yds!

[PanaDP]

When I started out with my 45-2.4" I was lead onto an initial test by somebody on the shiloh forum that showed me a lot. Figure out how far out you can seat your bullets so that they will have about a .010" jump to hit rifling. I do it by setting a bullet in the chamber, gently tipping the muzzle down so the bullet stops at the rifling, and then measuring from chamber rear to the bullet base with the depth gauge on calipers. Next, figure out how much powder, drop tubed, will 100% fill the space left. Load 5 of those, then load 5 with 2gr more while keeping the bullet seating the same which will require a little compression, then 4gr more than the initial load, then 6gr more, etc. until you get up to 8 or 10gr more or where compression is feeling pretty stiff. Go shoot groups and take notes. You will probably notice a bell curve in accuracy and also a change in amount of fouling. The quality of the gun's sound will also change from a "whump" like a muzzleloader to a sharper "crack" like a more modern rifle.

Keep in mind that none of those will necessarily be tack drivers unless you're on the lucky side. It's to demonstrate the effect of compression and it may tell you the amount of compression your rifle may like with that powder and bullet.

[montana_charlie]

Going from about 0.15" compression of 70 grains of FFg to about 0.25" compression of 70 grains of FFg produced a lot more fouling, and forced me to raise my sights 20 minutes at 100 yds!
This is not my advice, it is just a number I am passing on.

Some say that .385" of compression is ideal for Goex FFg.

CM

[PanaDP]

This is not my advice, it is just a number I am passing on.

Some say that .385" of compression is ideal for Goex FFg.

CM

My findings have been right in that range, too.

[Seth Hawkins]

This is not my advice, it is just a number I am passing on.

Some say that .385" of compression is ideal for Goex FFg.

CM

Thanks. ;-)

[Tatume]

Several people have suggested adjusting bullet seating depth to compensate for more or less powder. The three 45-70 rifles I own (Marlin 95 and two Winchester/Miroku High Walls) do not have any throat, and offer no flexibility in seating depth.

[Gunlaker]

Several people have suggested adjusting bullet seating depth to compensate for more or less powder. The three 45-70 rifles I own (Marlin 95 and two Winchester/Miroku High Walls) do not have any throat, and offer no flexibility in seating depth.

If you use a mould that has one or more driving bands at bore diameter you can seat then way out. I have a couple of these moulds. One of which allows me to seat the bullet about 0.2" into the case. With this bullet I can easily get 80+ grains of goex FFg Express into a .45-70 case, and have the benefit of excellent alignment of the bullet with the bore. If you don't mind exposed grease grooves this might work well for you.

Chris.

[montana_charlie]

This is not my advice, it is just a number I am passing on.

Some say that .385" of compression is ideal for Goex FFg.
Thanks. ;-)
You're welcome, but consider this ...

You can compress a 45/70 powder charge .385" and it will be a 20% reduction in powder column height.
or
You can put .385" of compression on a hundred grain charge in a 45/110, and you reduce column height by only about 15%

The guy who says .385" is optimum happens to shoot a 45/110.

If you put a 15% compression on a powder column that is '45/70 tall', that comes to .300".

I'm not saying what's good or what's bad. I'm just saying that the 'density' of the charges should be about equal when you compress .300" for 45/70 and .385" for 45/110.

CM

[Seth Hawkins]

You're welcome, but consider this ...

You can compress a 45/70 powder charge .385" and it will be a 20% reduction in powder column height.
or
You can put .385" of compression on a hundred grain charge in a 45/110, and you reduce column height by only about 15%

The guy who says .385" is optimum happens to shoot a 45/110.

If you put a 15% compression on a powder column that is '45/70 tall', that comes to .300".

I'm not saying what's good or what's bad. I'm just saying that the 'density' of the charges should be about equal when you compress .300" for 45/70 and .385" for 45/110.

CM

Understood completely, CM. Thanks.

[Seth Hawkins]

Several people have suggested adjusting bullet seating depth to compensate for more or less powder. The three 45-70 rifles I own (Marlin 95 and two Winchester/Miroku High Walls) do not have any throat, and offer no flexibility in seating depth.

That's why we use a tapered bullet. I referred to my use of the Lyman 457677 tapered bullet. It can be loaded with more of it out of the case than there is in the case. There are other tapered designs, as well as bore riding designs.

[RMulhern]

You can compress it until the case bulges!!

[Hang Fire]

I don't make much of a fuss about it, I compress the 2ff about 1/8" with good results. I just enjoy shooting without considering writing a thesis for each load fired.

[Hang Fire]

If you use a mould that has one or more driving bands at bore diameter you can seat then way out. I have a couple of these moulds. One of which allows me to seat the bullet about 0.2" into the case. With this bullet I can easily get 80+ grains of goex FFg Express into a .45-70 case, and have the benefit of excellent alignment of the bullet with the bore. If you don't mind exposed grease grooves this might work well for you.

Chris.


True, I had a Win. 1886 in .45-90 and I shot .45-70 in it accurately by just seating the boolit out

[hiram]

Tom--

This is my answer to compression > When you seat a bullet in the case as deep as you want it to be, the amount of powder which results in an accurate will be compressed as much as it needs to be.

Please read this--- It is an old posting of mine. I was not concerned with compression, I was concerned with accuracy:


I have a redding measure. I started with the minimum load to fill the case to the bullet’s base. That was #50 on the micrometer setting. Load 1 case, then I turned the setting, from 50 to 51, loaded another case, 51 to 52, load 1 case, 52 to 53, load 1 case. I did this for 17 loads. My charges were from 56.7 to 72.7 gr. The powder measure setting is not the grains, its just a control for you to load 20 cases with the same increment of powder between each load. You have to throw 2 or 3 charges to settle the powder after you make each change, but that takes no time at all. So now you have twenty rounds of ammo, each with a slightly different charge. Make a list of the increment setting and corresponding charge weight.

We go to the range with 2 targets. One at 100 yds (that's what is available to me) and 1 target on the bench with your equipment. You have a few extra rounds to get you on paper and now the fun begins. Once your on the paper, NO SIGHT ADJUSTMENTS. You fire a round, mark where is hits on the target on your bench with the load number, i.e., #1. Fire the second and mark it on the paper, #2. Fire them in order. Mark each on the target with its load #. After the 17 rounds, you will see some shots spread out and a cluster of others. Take the middle load for the cluster and that is your basic load-and you can fool around a little from there.

My load worked out to be 61.3 grains, but it is number 55 on the powder meter.
Don't confuse the meter seeting with the powder weight.

[montana_charlie]

I just enjoy shooting without considering writing a thesis for each load fired.


I had a Win. 1886 in .45-90 and I shot .45-70 in it accurately by just seating the boolit out
No thesis needed, I've heard enough ...

CM