The rifle was bought as new, unfired. There are no markings to indicate this rifle was reamed to 458 Lott after market.
I tested 6 rounds of 458WM with a case overall length of 3.556 to 3.579. The 458 Lott case overall length for the Hornady 500 grain round nose is listed at 3.585. Compared to the 458WM using the same bullet case overall length is 3.310.
At 50 yards: The 458 Lott lengths were 3-1/2 inches high with a 1-1/2 inch group. The 458WM lengths were centered zeroed with a 1-1/2 inch group. The powder charge, and primers used was the same for both case overall lengths; 63.8 grains of Reloader 7.
This test was just to check out the minimal amount of bullet performance with only ~ 5/16 of an inch seated in the 458WM case.
The next range day will be ballistics testing of the longer length rounds.
The average velocity with the current 458WM loads is 2089 fps. Velocity range: 2069 to 2109.
Load Data:
Bullets: Hornady DGS and DGX, and Woodleigh 500 gain Solids
Powder: Reloader 7, 63.8 grains
Primer: CCI and Winchester Standard Large Rifle
Length: 3.310 to 3.289 inches
I will be ordering some 458 Lott brass to do more testing but that will be in June when I return from RSA.
Problem 1: and I will be contacting Shawn at CZ-USA to verify, that this rifle is capable and safe to use 458 Lott loads before shooting 458 Lott ammo in it.
Problem 2: The reason for wanting a 458WM is to have sort of double duty rifle: 458WM and 45-70. A choice of calibers/loads for a wider choice of animals.
The 458 Lott magazine and chamber lengths are too long for proper functioning of the short 45-70 cartridge.
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Here is the email I received from CZ-USA:
Good afternoon,
That model is indeed chambered in .458WM. I’ll include my gunsmiths response upon my inquiry about the rifle.
.458 Win Mag will fit and fire with no issues in a .458 Lott chamber, since the latter is essentially just a longer .458 Win Mag by exactly 0.3 inches.
The only real problem would come when you try to fire the longer Lott right after the Win Mag, which would turn the carbon buildup into diamonds against the chamber wall. (exactly like firing a .357 Mag right after shooting some .38 Special)
Seeing as how that rifle left our warehouse well over a decade ago, it is possible that someone could have reamed it deeper but neglected to re-stamp it, but who knows?
That rifle no longer has parts available since the last time we sold one of those models was in 2019, but both calibers were produced by the factory and both use the same magazine body, so him seeing either cartridge fit in there is a non-issue.
Shawn Stark
Customer Service Representative
CZ-USA | Dan Wesson
Main: 1-800-955-4486 | Alt: 1-913-321-1811
I am wondering if we are talking about the same thing?
You state (my bold emphasis) "
I tested 6 rounds of 458WM with a case overall length of 3.556 to 3.579. The 458 Lott case overall length for the Hornady 500 grain round nose is listed at 3.585."
Unless I am completely off my rockers (?)
case length for the .458 Win is 2.5" and
case length for the .458 Lott is 2.8".
So it looks to me like you meant to say: " (my bold emphasis) "
I tested 6 rounds of 458WM with a cartridge overall length of 3.556 to 3.579. The 458 Lott cartridge overall length for the Hornady 500 grain round nose is listed at 3.585."
As previously stated,
cartridge length is vastly irrelevant to
chamber dimensions. In the framework of this discussion, only
case length is relevant to chamber dimensions.
Cartridge length is conditioned by the throat, which includes:
1- the freebore: the cylindrical, unrifled section of the bore directly in front of the chamber, allowing the bullet to accelerate without rifling resistance before engaging the lands;
2- the leade: the tapered section that transitions from the larger freebore diameter to the smaller rifling lands.
It is absolutely possible that a .458 Win
chamber with a long throat will accept .458 Lott
cartridge-length ammo assembled with .458 Win
cases and long bullets seated far out.
I am willing to bet that this is the case with your rifle, and this is totally OK.
As stated previously, to check if your rifle is
chambered for Win or Lott the very simple test is to try to chamber a Lott
case (2.8"). I am willing to bet that the bolt will not close because I am willing to bet that the chamber is only 2.5" long, as it should be for a .458 Win-stamped rifle **.
** that is unless a Lott reamer was pushed in the chamber by a bubbasmith.............................
Regarding your questions:
Problem 1: and I will be contacting Shawn at CZ-USA to verify, that this rifle is capable and safe to use 458 Lott loads before shooting 458 Lott ammo in it.
If as I expect your rifle has a Win
chamber, you will not be able to fire Lott
cartridge with a Lott 2.8"
case because your chamber is only 2.5" long. HOWEVER, you can easily fire Lott
cartridge-length ammo assembled with Win short
case and long bullets not deeply seated, because there is a long throat ahead of the short chamber.
Problem 2: The reason for wanting a 458WM is to have sort of double duty rifle: 458WM and 45-70. A choice of calibers/loads for a wider choice of animals.
Now you have me totally perplexed !?!?!?!
Again unless I am completely off my rockers (?), the .45/70 is a
rimmed cartridge. It is incompatible with a .458 Win or .458 Lott chamber. And it is generally incompatible with a stacked magazine. And it is certainly incompatible with feeding ramp geometry designed to feed rimless belted cartridges.
It seems to me that the proper way to look at the situation is the commonly advocated: "
The reason for wanting a 458 Lott is to have sort of double duty rifle: 458 Lott and .458 Win. A choice of calibers/loads for a wider choice of animals." This is further achieved by loading .458 Win with reduced load and light bullets. There are several threads on AH on this subject.
This being said, because the CZ .458 Win are built on the very long (.416 Rigby-length) CZ magnum action, the action and magazine are both longer than optimal for the .458 Win, so light .458 Win loads with lighter/shorter bullets may not feed very reliable.
I hope this helps. From where I stand, your rifle is just fine, but it seems that you have mixed up a few different things in your reasoning
I say this respectfully and I am just trying to help
