RG4570 and Cast Bullets

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RG4570 and Cast Bullets

Post by Ranch Dog »

All you wanted to know about cast bullet performance with the RG45-70. This is the results of 6 months work with my three cast bullet designs. I've included the Beartooth 525-grain Pile Driver but only shot three samples of it; however, I am confident in the performance based on my pressure testing work with my bullets against the calculations in QuickLoad.

I have chosen to reload the RG4570 to a max pressure of 35.0K PSI vs. what I and others load the Marlin 1895 to. The RG4570 is not a 1895 clone but a 336 clone and as such does not have the strength in the receiver at the barrel lugs. I'm very comfortable at this level of performance but it is at my own risk. The actual performance calculations are a Pmax of 40.0K and and Nominal Maximum Pressure (NMP) of 35.0K PSI. Pressure, like velocity, experiences a standard deviation with every shot and what the previous statement indicates is the the average pressure will be 35.0K PSI with the deviations contained inside 40.0K PSI. Your use of this information is at your own risk!

The RG4570 is a very accurate rifle. My work with the Hodgdon powders and all the bullets has proven that powder selection is going to be simply a matter of personal choice. Do your normal load work against a couple of suitable powders and make your own choice for your own rifle.

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The above is an example of what I've experienced with the rifle. The three bullets in the target where the Beartooth Pile Drivers at 50-yards (lower right quadrant target). The holes in the cardboard where from my 425-grain bullet in another target that has been removed from the back board.

Whether you shoot these specific bullets or not, the information should allow you to decide which bullet fits your shooting and hunting needs. I've presented the data with graphics below with just about every qualifier you can thing of.

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My formatted data, the data I use, is attached as PDF files. Those files are for reference only, your use is at your own risk! All the bullets where sized to .458" and used with a cartridge overall length of 2.500" which provided positive cartridge feed and chambering. The cases were trimmed using the standard, cataloged Lee Precision Case Length Gauge/Trimmer. These trimmers trim the brass slightly under the SAAMI spec, with any cartridge, which worked out very well for matching the case to the crimp groove. Some might ponder the loss of .005" of cartridge OAL, against that used with the Marlin 1895, but it is immaterial with a case of this size. With my load work, I used PMC brass and CCI 200 Large Rifle primers but any 45-70 brass and Large Rifle primer will provide the same performance.

Finally, the RG4570 has met my expectations as a lightweight carbine for hunting. At the bench, my 7 lb rifle can be brutal on the body. The rifle performed so well in every aspect that I sold my Guide Gun. I just received the latest Deer and Deer Hunting magazine and see that they listed the RG4570 in their five rifle "Hot Picks". I understand why, it is a heck of a rifle at a heck of a value.
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Re: RG4570 and Cast Bullets

Post by Quinc »

Thanks for all the info!
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Re: RG4570 and Cast Bullets

Post by pricedo »

If I could get the dedication, the attention to detail, the thoroughness and quality presentations from our team of graduate engineers in their professional work that this man (RD) routinely produces as a hobby I'd be a happy man. :D
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Re: RG4570 and Cast Bullets

Post by joec »

I have saved all of this with the rest of the information I've gathered on the 45-70. Now if someone would produce the bullets instead of the molds I would sure buy some. As for me making my own not for at least another year when I actually retire. Can't cast where I live now (at my business).

I do have a question though that, I've been trying to get an answer on for a while now. What is the rated pressure level for a 45-70 Rossi Rio Grande? Thanks in advance for any that knows.
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Re: RG4570 and Cast Bullets

Post by pricedo »

The below information is derived from anecdotal hearsay and is being presented for
discussion purposes only.
Do not base any actual load development on what you read in this post.
The RG is a 336 clone rather than a 1895 clone.
The 1895 is the stronger action with a max working chamber pressure of 40K psi.
I'm guessing the RG as a 336 clone has a max working chamber pressure of 35 K psi.
The 45-70 cartridge has a SAAMI published max working chamber pressure of 24K psi.
If you know that any of the above statements are incorrect please feel free to chime in.

Handy Little Chart of SAAMI MAX chamber pressures:

http://www.lasc.us/SAAMIMaxPressure.htm
Last edited by pricedo on 12 Aug 2012 16:45, edited 1 time in total.
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Re: RG4570 and Cast Bullets

Post by Zippidydoodah »

Thanks R_D for all your work. I have the lee molds in 300, 350 and 405. But will be getting yours based on your charts, etc. Did you do any of this in conjunction with cast boolit association or all on your own? I had purchased. The 7mm soup can and 6.5 military and they look like your design as well.again, thanks for improving bullet design and making it available to us.
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Re: RG4570 and Cast Bullets

Post by Ranch Dog »

Zippidydoodah wrote:Thanks R_D for all your work. I have the lee molds in 300, 350 and 405. But will be getting yours based on your charts, etc. Did you do any of this in conjunction with cast boolit association or all on your own? I had purchased. The 7mm soup can and 6.5 military and they look like your design as well.again, thanks for improving bullet design and making it available to us.
You're welcome, all the bullet design stuff has been by own work.

With the data posted earlier in this topic, I have pressure tested all the Hodgdon loads with a strain gauge attached to the barrel of the RG4570.
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Re: RG4570 and Cast Bullets

Post by doskiez »

This is some great work. I am somewhat new to reloading (year or so experience so far) and have just about collected all the hardware I will need to start reloading for my Rio Grand .45-70. I am working on a load with starline brass and Oregon trail laser cast bullets in 405 Grain with 2.51 COL. I have Varget powder on hand and would like to work something up with that before I go buy more powder. I am starting with a heavy trapdoor load with a preassure of 21K CUP as a base line to gague against factory produced loads. I need to do some math to see if the preassure increases linerly as you add powder for a given bullet and case volume, also if compression of the powder affects the pressure as well. Do any of you have experience with this load or a load with a cast bullet the same weight?
Thanks,
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Re: RG4570 and Cast Bullets

Post by Ranch Dog »

doskiez wrote: I am working on a load with starline brass and Oregon trail laser cast bullets in 405 Grain with 2.51 COL. I have Varget powder on hand and would like to work something up with that before I go buy more powder.
If you can give me the average bullet length, I can run this through QuickLoad for you. In that the bullet is plain based, 30.0 KPSI is about the best you can push it and Varget would be a good choice.
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Re: RG4570 and Cast Bullets

Post by doskiez »

Ranch Dog wrote:
doskiez wrote: I am working on a load with starline brass and Oregon trail laser cast bullets in 405 Grain with 2.51 COL. I have Varget powder on hand and would like to work something up with that before I go buy more powder.
If you can give me the average bullet length, I can run this through QuickLoad for you. In that the bullet is plain based, 30.0 KPSI is about the best you can push it and Varget would be a good choice.
My average length for the starline brass is 2.099
Bullet total avg length 1.05
avg distance from the base of the bullet to the cannelure is .63

Thanks for your assistance with load data from quickload. I will report back on performance, accuracy, and leading if any after a good trip to the range.
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