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Rio Grande 45-70

Posted: 17 Feb 2012 14:27
by SoCal44
Can the Rio Grande 45-70 be safely loaded to the Marlin 1895 specs. (which I believe is < 40,000 CUP)? In my reloading manual I see Trapdoor loads, Marlin Levergun, and Ruger #1 loads. I'm assuming I can use the Marlin loads.

Thanks

Re: Rio Grande 45-70

Posted: 17 Feb 2012 16:14
by Ranch Dog
SoCal44 wrote:Can the Rio Grande 45-70 be safely loaded to the Marlin 1895 specs. (which I believe is < 40,000 CUP)? In my reloading manual I see Trapdoor loads, Marlin Levergun, and Ruger #1 loads. I'm assuming I can use the Marlin loads.
Here is my take on it. The RG4570 is a 336 clone not a 1895 Clone. The 1895 action has a little more beef where the receiver meets the barrel threads. That said, here is how I'm proceeding with my RG4570 based on my pressure trace testing experience.

When using that equipment, barrel outside diameter vs. chamber diameter and brass thickness are settings used to calibrate the strain gauge. Using the RG3030 as the "know"; with its pressure standard against and dimensions against those of the RG4570 I feel good in estimating, for my use, what the RG4570 is capable of.

I use CIP standards where I can as they relate directly to what I see with the strain gauge equipment. The 30-30 has a 46.4K PSI Pmax and 40.6K PSI NMP (Nominal Max Pressure). Loads are generated to NMP so that the variations can be contained within the PMax. Pressure, just like velocity, varies and nothing should exceed the max.

For my RG4570 I compared how much metal is around the chamber to how much metal was around the chamber of my RG3030 (now a 38-55), and I use 40.3K PSI as the Pmax and 35.3K PSI as NMP. The larger bore leaves less metal and there is no way the chamber can handle the same pressures that the 30-30 is being subjected to. What that is in CUP, I don't know. I can guess at it but use data with PSI results in my reloading. This 35K PSI target is not that far off of what I use in my Marlins. For the "G" I use a 48.0K PSI Pmax and 42.0K PSI NMP.

Using a 350-grain bullet as an example and with the above referenced pressures, I would expect to see about 100 FPS less in my RG4570 with the typical powders used in this cartridge. My Guide Gun would produce 2060 FPS and the RG4570 1960 FPS. That is still an amazing amount of killing authority.

All of us 45-70 shooters realize that we kind of operate outside the box at our own risk. Using Marlin 1895 data in the RG4570 is a bigger risk than I will take.

Re: Rio Grande 45-70

Posted: 18 Feb 2012 15:49
by SoCal44
Do you have some "pet" loads that you're willing to share?

Re: Rio Grande 45-70

Posted: 18 Feb 2012 17:15
by Ranch Dog
Tell you what, I'm busy this weekend but let me format the the loads I'm working with for my three bullets and I will post them here early in the week.

Re: Rio Grande 45-70

Posted: 19 Feb 2012 00:09
by SoCal44
Much appreciated :)
Thank you!

Re: Rio Grande 45-70

Posted: 19 Feb 2012 21:43
by Ranch Dog
Decided to work on this tonight as I want to load up for a week of shooting this rifle. I'm going to run all three of my bullets through it and try to decide what role it will assume in my big bore lineup. The chart below is for my use with my bullet designs and for the powders I keep on hand. It is based on the pressure considerations in my posts above.

Image

I use normal reloading practices, starting 10% below my max and working up in five increments with each powder. While doing that, I compare actually FPS and PSI performance for each increment against the actual performance. Any difference is investigated.

As a side note, I went into Dick's in San Antonio today ended up talking to a salesman about the Marlins and Rossi they had on the shelf. The Marlins where Remlins and looked absolutely awful. The wood was broomstick quality. I was real sad to see it as I love a good Marlin. He also had a number of questions about my experience with the RG4570 as they are going out as soon as they come in.

Re: Rio Grande 45-70

Posted: 20 Feb 2012 11:16
by SoCal44
Thank you for this information. It's great to hear from somebody who is using the same rifle.
The manuals I have are sort of frustrating as I'm relatively new to reloading.
On the Hodgdon website under the "Lever Actions" load data the STARTING load for 350gr Hornady JHP is 48.5 grains. In the Hornady load book under '1895 Marlin' their MAX load for the same bullet and powder is 1/10th of a grain lower at 48.4 grains.
Hodgdon STARTING load = 48.5
Hornady MAX load = 48.4 :o
Confusing, and possibly dangerous!?

For the record, I'll be using Lasercast 350 gr. and Missouri Bullets 405 gr. with H4198, H335 and Ramshot X-terminator.
Am I correct in assuming I can use the same load data as for JHP's?

Again, thank you very much

Re: Rio Grande 45-70

Posted: 20 Feb 2012 17:20
by Ranch Dog
SoCal44 wrote:For the record, I'll be using Lasercast 350 gr. and Missouri Bullets 405 gr. with H4198, H335 and Ramshot X-terminator.
Am I correct in assuming I can use the same load data as for JHP's?
It is tough to compare a load if you are not using the same bullet which was used in generating the load data. The reason for this is that the even though the bullet might be the same grain weight, the bullet's length might be different which ends up effecting the compression of the load and the pressure it generates. I would doubt that the the Hornady 350 Round Nose, the Lasercast 350, and my TLC460-350-RF are the same length so it is possible that each of the three might have a different max charge when using the same cartridge overall length because the powder compression would be different.

Re: Rio Grande 45-70

Posted: 20 Feb 2012 17:29
by Ranch Dog
The best way to end the speculation is to give me a list of the bullets you are going to use and their length plus the cartridge OAL that you are going to use with each bullet. I will run the data through QuickLoad for you if you tell me what kind of pressure you want to run your loads to.

Re: Rio Grande 45-70

Posted: 20 Feb 2012 18:16
by Dan 444
I don't have a RG4570 yet, but just wanted to share that H335 is my friend in my 1895 with any bullet.....especially 51g with a 425g cast bullet.

Dan