downloading a 458 Win mag to 45-70/Ruger #1, thoughts?

saskgunowner101

saskgunowner101

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Recently bought a Zastava chambered in 458 Win mag, and want to play around with some cast bullet loads (405 and 500 grain) starting low and working my way up. As mentioned in another thread, this stock does a left hand shooter no favors at all. I'd rather not start at the top end and be scared of the thing, which I'm sure would happen with a full tilt load.

Anyone have thoughts on using Ruger #1(45-70) data out of the Lyman Cast Bullet Handbook?
 
The data for 458WM in the Lyman Cast Bullet Handbook shouldn't be too bad compared to full power, jacketed loads. Personally I would just start with those. You should be able to fairly easily use the 385gr starting data for 405gr bullets and 475 starting data for 500gr bullets since the pressures are pretty low at those levels. Could reduce them by a further 10% if you want.

Using Unique for the 405gr should be very mild in terms of recoil. To reduce it even more you could try IMR Trail boss using the standard load development steps.
 
I like using Unique in the 45-70, but I wasn't planning to go that pokey with the 458. I tried a few cartridges loaded with 405 grn/28 grains 2400 which should be moving around 1400 fps. I thought I'd then walk up with IMR-4198, but the starting loads for 458 start around 2000 fps. That's why I was curious about the 45-70 data for the Ruger, it walks right up the 1600-1900 fps zone I want to work up and through.
 
In the 458 Win Mag, your upper limit for IMR-4198 for any bullet weighing up to 500 grs, is a full case. The lower limit is simply the point where the pressure is becomes too low to provide reliable ignition - about 15K psi IMO. I have found that 38.0 grs of IMR-4198 with any bullet weight between 300 and 500 grs provides that minimum pressure and hence reliable ignition, and you might be able to go lower, but I haven't tried. I have never found filler necessary with IMR-4198, and in fact don't use loads that recommend it.
 
I've loaded as low as 30grs of IMR4198 with cornmeal filler under a 420 grains cast lead flat base bullet with very good results. These are feed into my Ruger #3 45/70 and I have a few groups just under 1" at 100 yards, but, my skills as a shooter usually have at least 1 flyer out to 2"(or more...can we say flinch) and 1" or less is rare for me.
 
Please please be sure to use a foam filler wad when using a low weight load!

Why?

Because if the powder is low in weight the powder may shift so the primer is not fully covered or is covered by little powder. If that is the situation the primer ignition can cause the primer flame to jump across the load for a total burn instead of a progressive burn. Then the pressure changes Dramatically !!!. That can cause the case to rupture and can be so bad to cause the barrel to bulge or burst.So use a foam wad over the reduced load, between the powder and the bullet.

And try the Hornady 350 grain rn's. they are accurate and great to 200 yds !
 
sweetheart said:
Because if the powder is low in weight the powder may shift so the primer is not fully covered or is covered by little powder. If that is the situation the primer ignition can cause the primer flame to jump across the load for a total burn instead of a progressive burn. Then the pressure changes Dramatically !!!. That can cause the case to rupture and can be so bad to cause the barrel to bulge or burst.So use a foam wad over the reduced load, between the powder and the bullet.
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I've read pretty much everything I can find about this phenomenon (usually called Secondary Explosive Effect or SEE). In laboratory tests it is only repeatable with under 30% case volume loads of slow magnum powders. Also the only lab that has performed it successfully I believe was Norma in Sweden and they could only get it to happen around half the time when they intended to. With fast powders such as pistol, shotgun, or very fast rifle powders no laboratory has been able to cause a SEE. Some people report reduced accuracy or failure of ignition with very small charges of fast powder though.

There are many reports of what people believe to be SEE's occurring with fast powders but none of these have been able to be recreated. It could be an accidental double or triple charge that would cause the same effect.
 
get a can of trail boss and go have some fun............when you have a need for speed go back to the 4198 powder......
 
Well, I ended up with some strange results with IMR-4198 to say the least. I was using Lee scoops, the 3.1 cc (supposed to be 39.2 grains), and the 405 grn bullet seated to 3.19? or there abouts. I think I was getting hangfires, very subtle, but noticeable. And the last of 5 shots failed to ignite and only popped the primer, leaving me a stuck bullet with a mess. I've used the same powder in the 45-70 with lower charges, so I'm wondering if it's a powder problem or primer problem. I rolled a few more with an increased charge and more crimp so I'll give those a try. Sound like a need for magnum primers?
 
saskgunowner101 said:
Well, I ended up with some strange results with IMR-4198 to say the least. I was using Lee scoops, the 3.1 cc (supposed to be 39.2 grains), and the 405 grn bullet seated to 3.19? or there abouts. I think I was getting hangfires, very subtle, but noticeable. And the last of 5 shots failed to ignite and only popped the primer, leaving me a stuck bullet with a mess. I've used the same powder in the 45-70 with lower charges, so I'm wondering if it's a powder problem or primer problem. I rolled a few more with an increased charge and more crimp so I'll give those a try. Sound like a need for magnum primers?
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Sounds like classic very low pressure symptoms. What MV's were you getting? How far from the lands are your bullets when used ay an OAL of 3.19"?

For you H4198 loads that worked well in the 45-70, how much did you use? It only has about 75% of the capacity of the 458 Win Mag, so you need more to get the same results. 38.0 grs has worked well for me, but you'll need to use more. I doubt it's primer problems, and do not recommned useing magnum primers. A crimp will help, but I'd also go to 44.0 and work up from there. You seem to be on the fringe, and it's pointless to go up by only 1-2 grs.
 
I didn't run it over the chronograph, as I have no plans to stay so low (2400 seems to fit the bill for low end loads, will get that sorted later). Previous to these 5, I had tried the same powder charge with the bullets seated a bit deeper, about one band less on the lube grooves 3.06-ish and they all fired, the only thing I did different on the next batch, was put them further out to get closer to the lands. I didn't want to leave too little of the bullet left in the case. I've read these rifles have a long throat, so I'm pretty sure I have a lot of room to go, only limited by the magazine length.

I looked back in my notes, and had used 28 & 30 grains IMR-4198 with both the 405 grn and 500 grn bullet in the 45-70, and also 36 grains with the 405.

I'll load up with 44 grains and see what happens. I'm starting to question my being so low on the powder charge though, as recoil is not really anywhere's where I thought it would be. Maybe the weight of this rifle?? I recall the Handi rifle being a lot more punchy.
 
saskgunowner101 said:
I didn't run it over the chronograph, as I have no plans to stay so low (2400 seems to fit the bill for low end loads, will get that sorted later). Previous to these 5, I had tried the same powder charge with the bullets seated a bit deeper, about one band less on the lube grooves 3.06-ish and they all fired, the only thing I did different on the next batch, was put them further out to get closer to the lands. I didn't want to leave too little of the bullet left in the case. I've read these rifles have a long throat, so I'm pretty sure I have a lot of room to go, only limited by the magazine length.

I looked back in my notes, and had used 28 & 30 grains IMR-4198 with both the 405 grn and 500 grn bullet in the 45-70, and also 36 grains with the 405.

I'll load up with 44 grains and see what happens. I'm starting to question my being so low on the powder charge though, as recoil is not really anywhere's where I thought it would be. Maybe the weight of this rifle?? I recall the Handi rifle being a lot more punchy.
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You need to chrony the next batch, and also find out just how long your throat is with those bullets. The chrony tells you a lot about pressure, and I still think that it's a pressure thing. As for the throat, if your throat is so long that the bullet is completely out of the neck before it engages the rifling, you need to choose another bullet - that temporary state of "limbo" is a recipe for hangfires. I doubt that's an issue with a 405 gr RN bullet, but it's common with lighter "pointier" bullets in the various 45's.
 
I went and made up a dummy cartridge with the 405, 3.355 with approximately .16 of bullet left in the case(one band, one groove) and it didn't engrave any rifling on the bullet. The nose of the bullet is smaller diameter than .458 for the first .38", so that would probably explain that away. I'll chrony my loads this afternoon, and hope for the best. Accuracy seemed to get better going from 3.06 up to 3.19 so I don't think I'm going to give up yet. How much fun would that be, if everything just worked and shot like a laser beam on the first go?
 
I'd not use that bullet anymore, and go to something else longer and/or with a rounder nose, such as the Hornady 500 gr RN.

When a bullet is in "limbo" (neither engraved in the rifling nor partially in the neck of the cartridge), you have brief intervals upon firing when the pressure that has just started to rise, drops rapidly and then rises again, usually much higher than it would have under normal circumstances - the "hangfire" you have described.
 
Andy said:
I'd not use that bullet anymore, and go to something else longer and/or with a rounder nose, such as the Hornady 500 gr RN.

When a bullet is in "limbo" (neither engraved in the rifling nor partially in the neck of the cartridge), you have brief intervals upon firing when the pressure that has just started to rise, drops rapidly and then rises again, usually much higher than it would have under normal circumstances - the "hangfire" you have described.
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So....would seating the bullet deeper in the case prevent this pressure spike, and throw accuracy out the window at the same time? Would a greater charge possibly cause enough initial pressure, that any pressure drop when the bullet is in limbo, would be smoothed out and not cause the hang fire?

I don't know if I should be worried to fire these over a chronograph now.

I should add, primers of fired cases were fine, the cases showed signs of sooting as I've noticed on other low pressure loads.
 
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I'd stop using that bullet - your gun was given a throat not suitable for it. If you want to "plink", I'd get some 500 gr cast RN's and go with the load you started with.
 
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