45-70 max cartridge length

[kingofbattle1985]

One of my buddies told me that i should try to load as close to the max cartridge length as possible (2.550)! My loads are coming in at 2.530 for a hornady 300 gr. JHP and 2.007, is this safe? Why wouldn't it be? I thought that as long as I wasnt over the max overall cartridge length than it would be safe! Please any help would be greatly appriciated!

The King:banghead:

powder charge= 56.1 grns. imr 3031 for both bullets

my bullets are also bulging the case,any explenations on this,is it safe?

 

[steveno]

just let the oal length be controlled by crimping in the cannelure of the bullet. I don't know where you came up with the 2.007 dimension as the 45-70 case is longer than that. you need to pay attention to the 2.550 if you have a Marlin rifle as anything longer will not feed through the magazine. been there and done that

 

[Coltdriver]

I think that one of the most important things that you can do when you reload is to know what your particular chamber length is.

They are not all the same.

Some have a very long throat and you could never get the bullet close to the lands.

Some have a very short throat and you can find yourself with a bullet touching the lands when you don't think your close.

Being at or under the max cartridge length is meaningless until you know your actual chamber length. On top of that your max col will vary with different bullets.

I have only reloaded for a couple of years but I discovered the importance of this chamber length question when I reloaded some seriously hot rounds into a .243 Ruger #1 and ruined some brass before I discovered I was pressing the bullet into the lands. These were under the col length by a lot. The pressure spike that this causes is fairly significant.

It is true that if you can get your bullet to engage the lands sooner that you will pick up a bit of accuracy. I don't know how dramatic this is with a 45/70 but with my other rifles it makes a noticable difference.

I just started reloading for 45/70 for an encore so I will be experimenting too.

 

[GooseGestapo]

The 2.550" oal. for the .45/70 is so that it will feed through the various leveraction rifles, such as my Marlin 1895G.

If you are loading for a Single shot, you can seat the bullets out a bit further.
If you are going to seat them to touch the lands, you need to back down the load a bit and work up, IF using loads near max.

Most .45/70 loads are well below max, so you need to adjust the length to maximize accuracy. This is usually touching or back no farther than 0.050".
I find that .005-0.015 works best.

For magazine fed rifles, It is what will allow the ammo to feed through the action without jamming.

For some rifles, this works out just right; an expample is my Rem M7 in 7mm-08 and my Savage M110 in .300RUM.

Others, such as my Parker-Hale(Midland Arms) .30/06 and MkX Mauser in .338/06, a bullet seated to fit the magazine is 0.050 or further from the throat.

However, neither of the former will shoot anywhere as well as the latter two.

Go figure !!

BTW, with some of the cast bullets, the 2.550" works out quite well, as I found that with a NEF I had, that seated and crimped, the 340gr and 405gr FN's were only about 0.025" off the lands. It also works well with the 405gr Remington Jacketed FN.
All these have a good reputation for accuracy with appropriate powder charges.