45/90 loads vs 45/70

[oldred]

I know there was a similar thread a while back, and I participated in the discussion, but I still am a bit confused. While there are literally volumes of info on loading for the 45/70 there is very little it seems about loading for the very similar 45/90. What the other thread was about, and what I am still wondering about, is what happens when 45/70 load data is used for the slightly longer 45/90 case? While I don't expect exact specifications nor specific load data I was wondering what happens, do the pressures tend to go up or down due to the slightly longer case assuming the same powder charge and bullet weight? Could it be that it's not as simple as that and other factors have to be considered? Like I said I do not expect there will be an exact formula for determining pressure changes for a given case length but I would like some experienced opinion on what can be expected as far as pressure changes.

[NickSS]

If you are talking smokeless powder the pressure will go down with the larger volume case. If you are talking black powder you would have air space which is not conducive to good accuracy.

[oldred]

I guess basically what am wanting to know is about the safety of using 45/70 load data (smokeless) in a 45/90 case, for instance mid-range 5744 loads with 500 gr bullets (just an example). I just was not sure what to expect with more air space in the case, sure would be nice if there was more loading data available just for the 45/90.

[leadman]

In your example I don't think there would be a problem. If you were using minimum loads of 45-70 data in the 45-90 there would be a remote possibility of sticking the boolit in the barrel.

As an example of a large case I shoot a 43 Mauser with 20 grains of 2400 and a 340gr boolit. Does very well as far as accuracy, velocity is fairly low though.

[Mk42gunner]

The .45-90 Winchester typically had a slower twist than the .45-70, since it was loaded with 300 grain bullets, thus they probably would not stabilize a 500 grain bullet. The Sharps .45-2.4" version I am not sure of the rifling twist.

Robert

[oldred]

The .45-90 Winchester typically had a slower twist than the .45-70, since it was loaded with 300 grain bullets, thus they probably would not stabilize a 500 grain bullet. The Sharps .45-2.4" version I am not sure of the rifling twist.

Robert



The barrel is a Green Mountain 1:18" twist.

[GARCIA]

You shooting one of the recent 45-90's made in a limited run, an original Marlin/Sharps or Winchester?

Lyman 48 Has a full page dedicated to the 45/90.

I have an original that I use the data from the Trapdoor 45-70 as a good start. The 45/90's pressures will be lower when using that data.

I have another one on the 1886 Winchester/Miroku platform that was sent to Turnbull for work. It was rechambered from 45-70 to 45-90. In this rifle I will be using the current Lyman 48 information.

Tom

[geargnasher]

+1 on the Lyman #48 45/90 WCF data.

I load my Shiloh to somewhere between starting 45/90 loads and max trapdoor loads, and I use 500 or 535-grain boolits. I don't know who would want to shoot even midrange 45/90 smokeless loads with those heavy boolits, even a 13.5 lb rifle kicks like a MULE.

I recommend 4198, 5744, and Reloder 7.

Gear