Comparing 45-70 and 458 Win Mag

[tazman]

I recently acquired a Ruger model 77 Dangerous Game rifle and have reached the stage where I am ready to start loading for it.
I have a Lee 340 grain plain based boolit mold and have cast up some from range scrap sweetened with Linotype(sorry, I don't have a specific mix) and water dropped from the mold to harden it.
They measure right at .458 so I just tumble lubed them fairly generously.
I am looking for velocities in the 1300-1500 fps range.
There is almost no data available from published sources that fits in this range for the 458.
Do you think that using data from the 45-70 that fits this speed range would work or at least be close?
I don't know how much difference there is in the capacity of the brass for these two cartridges.
I can't compare since I don't have any 45-70 brass.
The powder I am currently using is IMR 3031. Thinking about 49 grains to start out with.

[DonMountain]

That .358 bullet might be a bit small for a .458 rifle bore.

[Nueces]

Your proposed load would certainly be safe. I took a look in the Lyman "Handbook of Cast Bullets", the 1958 grand daddy, and found loads for the 45-90 with the L457192, a 345 grain CB. The 458 has a case volume only slightly larger than the 45-90. Loads of interest to you were:

25.0/2400, MV 1500
42.0/4198, MV 1400
50.0/4895, MV 1365
18.4/Unique, MV 1485

They also showed a 45-70 load of 49.0/3031 under the 325 grain L457122, MV 1690.

The site http://kwk.us/cases.html shows case capacities as: 45-70 = 79 grains water weight, 45-90 = 90 gr, 458 = 94 gr.

[tazman]

Thanks for that info. I'll start with the 49.0 of 3031 and chronograph it and go from there.
Looks like it might be as slow as 1500 fps. That would be about perfect for what I want to try.
I can always increase the powder charge if I need to.

[Lloyd Smale]

paco kelly once gave me a load suggestion for my #1 458. It was a 405 rcbs rfgc and 22 grains of 2400. It shot clover leafs at 50 yards and is mild in recoil but still more then capable of killing a 300 lb animal.

[tazman]

paco kelly once gave me a load suggestion for my #1 458. It was a 405 rcbs rfgc and 22 grains of 2400. It shot clover leafs at 50 yards and is mild in recoil but still more then capable of killing a 300 lb animal.

That is the fun part about what I am trying to do. A boolit that size doesn't need to be going really fast to punch through anything I will be shooting at. Just accurate out to 100 yards.

[Larry Gibson]

I use 3031 in the 45/70 with 350 - 415 gr cast. I push the 350s to 1500 fps. I've found a Dacron filler enhances accuracy. As mentioned the 458 Win Mag has just slightly more capacity than the 45/90. For 1300 - 1500 fps I'd suggest starting at 40 gr 3031 with a Dacron filler and go +/- from there till you get what you want.

[Greg S]

Here are a few loads out of the Lyman 3rd edition for the 458 Win Mag

Win brass and LRP

457191 292 gr sized 459

Unique 19.0 - 23.0 gr 1460 - 1625 fps

2400 28.0 - 33.0 1585 - 1765

4227 44.5 - 50.5 2100 - 2305

457124 385 gr sized .459

Unique 18.0 - 22.0gr 1315 - 1510 fps

2400 25.0 - 31.0 1310 -1565

4227 44.0 - 50.0 1935 - 2090

I have a friend with a Win model 70 set up with a rear peep. I've had some fun plinking with that rifle shooting the Lee 459-500 3R and I believe 18.0 of unique. The soft push allows you to focus on sights and trigger and you move up in velocity. It was such a hoot, I picked up a CZ in 458 Lott to do the same and as a stopping rifle. Granted, it gets shot more with cast but it gets the manual of arms down for when it is needed.

[mehavey]

You're going to find out that your 458WinMag has a very long throat -- and is likely not going to like lighter/shorter bullets.
Before you load up, I'd see how far out you have to seat the bullet to engage the lands.

- Pull bolt and run bare bullet into chamber, held against rifling w/ a pencil/eraser
- Run a dowel/cleaning rod down to meet the bullet and Mark it at the muzzle.
- Push out bullet, replace/close the bolt, and run the rod down to meet the bolt face: Mark it again.
- Pull the rod and measure the distance between the marks.
- Let us know...

Notwithstanding resultant seating depth....
Personally, I'd go with Unique and/or AA5744 for the velocity regime you're looking at w/ that light a bullet.

You might also find this useful:
https://thefiringline.com/forums/sho...d.php?t=533432

[tazman]

I din't know or think about the throat being so long that it might be a problem. I will check that later.
I have some rounds loaded up with a fairly light charge of 3031 and will see what they do tomorrow morning. That will give me a baseline to start with.
Experimenting will begin after I get some rounds on target.
Looks like I need to get another type of powder or two.

[beagle]

Amen on the long throats on .458 Win Mags. I had a Number 1 Ruger that had a throat that looked like an on-ramp on a freeway. Would only shoot cast loaded way out. If you're interested, I still have my chronographed data that I'd be willing to share. Just PM me with an e-mail address and I'll send an Excel spreadsheet with my data./beagle

[tazman]

beagle----I got the data you sent. I am going to take some time to study it.

I got to the range today. The loads I had with me did not work worth beans. I could barely keep them on a sight in target at 50 yards.
You guys were right about the freebore on the rifle. The boolits I was using would not even be in the case if loaded to touch the rifling. I am going to need some much longer boolits.
Mehavey--- I used your method and found the length of the freebore as well as what the OAL for this boolit would need to be even though I could not load them this long. According to my measurements, the freebore in this rifle is .650 inches long. It's going to take a long boolit to take up that much space.
I didn't chronograph the load this morning since it was shooting so badly. I was half afraid I would shoot my chronograph if I tried.
Oddly enough, none of them tumbled. They all went through the paper nose first.

[mehavey]

Try the Lyman Postell (457132), cast no harder than Lyman#2 air cooled (15)

[cajun shooter]

I'll have to put a second on the Postell 457132 for your 458 Win. A friend of mine started going to Africa back in the early 80's and he would bring me all of his rifles to set up loads for. The Postell is my favorite for my BP loads but will also give good results with smokeless and a semi-hard bullet. The 458 does have a longer throat and it's a rifle that will take down any game that walks this earth. My friend took all the Dangerous game in Africa with his.
If you decide to try some 458 rounds, make sure that you have plenty of eye relief on your scope. The owner received some scope eye before he learned his lesson. Enjoy your shooting, David

[Lloyd Smale]

What I used to do in my #1 was seat the 405 or 500 rcbs rfgc out a bit. Id crimp on the top lube grove.

[Stephen Cohen]

I agree with those loads of 2400 and Unique, you will find them very accurate but I doubt you will see that accuracy until cast diameter is at .460 minimum. I have found my 458wm loves cast of this diameter with a gas check, to date I have used 500gr Lee gc, RCBS 300 gc 460gr CBE gc and all shoot into inch and a half all day. I cast with wheel weight alloy sweetened with some tin and now HI-TEK coat all my projectiles which gives me better accuracy and uniform groups. I found H 4198 to be a dangerous powder to use for reduced loads, squib loads and projectiles stuck in the barrel were the norm, the powder never burned and was still in case and lightly burned a yellow colour. I found H4895 to also be useless in reduced loads using their recommendation of the 60% rule, H4895 was a reasonable powder from 48grs up to maximum. I hope this is a help. Regards Stephen

[tazman]

I finally got to the LGS and picked up a bottle of Unique. I also have another mold coming in a 500 grain boolit. This one is supposed to cast at .460 so it should be a better choice.
I loaded up a few of the Lee 340 grain boolits with Unique. Loads are 18.0 and 20.0 grains. I seated the boolit out as far as I thought practical. I will try those as soon as I can get to the range.
I will try the 500 grain boolit as soon as I can get some boolits cast and loads assembled.

[mehavey]

Again, see https://thefiringline.com/forums/sho...d.php?t=533432 for what you want, in the regime you want.
Don't fight the 458's throat...go ahead and use it.

[tazman]

That was a good idea. I am going to be near a Staples this morning and will pick some up.

[mehavey]

Make sure they're corn starch -- not poly
https://www.uline.com/BL_2001/Biodegradable-Peanuts