Shoot 45-70 Gov in a 458 Lott ???

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RSA1

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Hi,

Armco is selling an expensive 458 Lott Ruger (Mod77 RSM) and claims the following:

..."the 458 Lott (which BTW can fire 45-70 and 458 Win as well, making this a truly versatile rifle... "

I have never heard of this being possible, and the much larger rim diameter of the 45-70 should make it impossible to even fit into the chamber of the 458 Lott. Also, to my mind, the smaller body diameter of the 45-70 at the head will cause the case to split if somehow Bubba got the 45-70 to chamber, thereby releasing a lot of dangerous gas. I also know that the headspace of the 450 Marlin is far greater than the 458 Lott, so it could not be that they intended to say 450 Marlin.

Perhaps their gunsmiths can help me understand how they manage this. I love the work Armco has done on some of the 454 Ruger SRH revolvers I have seen advertised, but 45-70 in a 458 (Lott or Win Mag) I need to see before I shall believe this. Even shooting regular 230gr 45 ACP in a 454 Casull does not make much sense (as will be the case with a 45-70 in a 458 Lott), as the bullet will have already left the case mouth even before it fully engages the rifling, thus resulting in poor accuracy.

RSA1
 
That sounds really iffy to me. 458 Win Mag in a 458 Lott, sure, they have the same head size and belt dimensions, could work, but 45-70? Doesn't seem (safely) possible to me.
 
The 458 Lott is a lengthened 458 Win mag, so the Winchester round will work in a pinch. 45/70 I don't think would work at all, probably not terribly safe to try either.
 
Considering that the 45-70 is a rimmed cartridge and that the 458 Lott is a belted case I would think that there would be serious headspace issues. The rim on the 45-70 is 0.008" smaller than the belt on the Lott so it should chamber but the front of the belt in the chamber is 0.220" forward of the bolt of the Lott and the rim on the 45-70 is only 0.070" thick leaving a 0.150" gap between the bolt face and the base of a 45-70 if it is fully forward in the chamber, at which point the firing pin would not hit the primer anyway but if the cartridge was held against the bolt face by the extractor and the firing pin did ignite the primer there would be a 0.150" ring around the base of the 45-70 case unsupported which depending on the load could rupture. My thoughts anyway.
 
Silverback, The rim of the 45-70 Gov. is LARGER (.608" or 15.44mm) than the belt of the 458 Lott (.532" or 13.51mm; Speer Reloading MANUAL #14), and this was one of the points which I made in my original post.

Talking of different cartridges used in the same firearm (and non firearm Antique shooting tools), my Glock 20 reliably feeds and safely fires 40 S&W ammo from the 10mm magazine in both 10mm Auto barrels (both Glock original) which I have. Obviously here the extractor holds the case close enough to the bolt face to ensure reliable ignition, but primers on the 40 S&W cases show the typical flattened surface which one sees in firearms with a too long headspace. The loads however feel like 38 Spl being fired in amongst full 357 Mag loads.

RSA1
 
You might get away with a 450 Marlin. Also a belted case, rim and base diameter is very close, if not the same. Check the length of the belt to see if they are the same though, I don't have that info.
 
RSA1 said:
Silverback, The rim of the 45-70 Gov. is LARGER (.608" or 15.44mm) than the belt of the 458 Lott (.532" or 13.51mm; Speer Reloading MANUAL #14), and this was one of the points which I made in my original post.

Talking of different cartridges used in the same firearm (and non firearm Antique shooting tools), my Glock 20 reliably feeds and safely fires 40 S&W ammo from the 10mm magazine in both 10mm Auto barrels (both Glock original) which I have. Obviously here the extractor holds the case close enough to the bolt face to ensure reliable ignition, but primers on the 40 S&W cases show the typical flattened surface which one sees in firearms with a too long headspace. The loads however feel like 38 Spl being fired in amongst full 357 Mag loads.

RSA1
Click to expand...

Damn, I had to find the one bad drawing of a 45-70 cartridge for reference, well I guess that the bolt should not close if the 45-70 brass does not fit in the Lott's bolt face, if it did there would still be a 0.150" wide band of unsupported brass just above the rim of the 45-70.
 
in a 458 lott chamber , wouldn't a person have to also cut the rim of a 45-70 into the end of the barrel as well .

so just from a headspace point of view it might work .

but where the 45-70 lacks the belt of the 458 lott , this area would be unsupported and after a few firings would it eventually "fireform " it's self a belt . ... this unsupported area would be around 150 thou wide

my concern would be , would the case head not want to separate around the new fireformed belt ?
 
Hi tjsudbury,

As indicated in my opening post, the headspace of the 450 Marlin is larger (6,40mm) by deliberate design than the typical belted case (458 Lott, 375 H&H, 300 Win Mag, etc) which is 5.59mm, so in well made rifles, you would not be able to close the bolt on a 450 Marlin cartridge fed into the chamber of a 458 (Lott or Win mag) rifle.

Perhaps Armco can comment and clear up the confusion.

RSA1
 
RSA1 said:
Hi tjsudbury,

As indicated in my opening post, the headspace of the 450 Marlin is larger (6,40mm) by deliberate design than the typical belted case (458 Lott, 375 H&H, 300 Win Mag, etc) which is 5.59mm, so in well made rifles, you would not be able to close the bolt on a 450 Marlin cartridge fed into the chamber of a 458 (Lott or Win mag) rifle.

Perhaps Armco can comment and clear up the confusion.

RSA1
Click to expand...

Brain fart on my part
 
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