Shooting 458 Win Mag ammo out of the 458 Lott

[Ku-winda]

Good evening - I'm looking for a little guidance on the subject. I just acquired a CZ 550 in 458 Lott and have a few questions about ammo use. I have always heard one of the great advantages to owning a Lott is the ability to use 458 Win Mag ammo if you were to ever get in a pinch. I have also read from some here on the Forum about the ability to load the cartridge down for practice purposes. I have a couple of questions as it relates to both these items. First, is the use of 458 Win Mag ammo relegated only to emergency situations or can it be done on a regular basis without fear of damaging the throat of the barrel. I may not be using the proper terminology here, but when I look at the difference between these two cartridges side by side, I have to wonder if there isn't some kind of "jump" when the Win Mag ammo is fired. If this doesn't create any issues, would it then not make sense to just use the 458 Win Mag ammo (which I have plenty of) in lieu of 458 Lott downloads for practice? Any insights on the matter would be appreciated.

 

[RR 314]

It will have some “freebore” shooting the Win., but accuracy should be fine for practice. The Win., with freebore will be at lower pressure and should (in theory) have 25-30 percent less recoil than standard Lott loads. Just make sure your POI is where you anticipate it being with your hunting rounds.

 

[Ku-winda]

It will have some “freebore” shooting the Win., but accuracy should be fine for practice. The Win., with freebore will be at lower pressure and should (in theory) have 25-30 percent less recoil than standard Lott loads. Just make sure your POI is where you anticipate it being with your hunting rounds.

I was hoping that would be the case, thanks!

 

[One Day...]

Agreed! Not to mention that it will take a lot more .458 Win rounds than most people shoot in their entire life, to erode a .458 Lott barrel throat. As to the concept of freebore, I believe that it can be safely said after decades of high intensity overbore Weatherby cartridges, that it is OK.

 

[Ku-winda]

I'll give it a whirl this weekend, thanks.

 

[cajunchefray]

I'll give it a whirl this weekend, thanks.

Let us know how it works for you.

 

[Ku-winda]

Absolutely, thanks!

 

[matt85]

As already said, it won't hurt your rifle. Accuracy may suffer a little and POI won't be the same but that's all. Happy shooting!

 

[Nhoro]

My cz was a win mag, now reamednto lott. I had win mag ammo which i ised with no problems. Chrono speeds were the same as the win mag chamber and accuracy was also the same. I just took a little extra care to clean the chamber after- you dont want the lott cartridges to stick in a dirty chamber

 

[Mark Biggerstaff]

I have a CZ 458 Lott. I shoot Swift factory 458 lott Aframes as primary load in it. For a solid load, have found the Swift 458 win mag Breakaway Solid hits same POI at 50 and 100 yards for me. I can get the win mag load but been unable to get the Lott load in breakaway solid to try. You would have to shoot a lot of win mag loads before worrying about throat issues.

 

[Ku-winda]

My cz was a win mag, now reamednto lott. I had win mag ammo which i ised with no problems. Chrono speeds were the same as the win mag chamber and accuracy was also the same. I just took a little extra care to clean the chamber after- you dont want the lott cartridges to stick in a dirty chamber

I will definitely make sure I do that - thanks for the tip!

 

[Ku-winda]

I have a CZ 458 Lott. I shoot Swift factory 458 lott Aframes as primary load in it. For a solid load, have found the Swift 458 win mag Breakaway Solid hits same POI at 50 and 100 yards for me. I can get the win mag load but been unable to get the Lott load in breakaway solid to try. You would have to shoot a lot of win mag loads before worrying about throat issues.

Thanks Mark - I will start with those loads and see if I get the same results.

 

[Luvthunt]

Had a very early Lott back in the day when we were making our Lott brass from fire formed 375hh . Shot several hundred 458 Win. thru it early on never saw any erosion with the bore scope we had a the time.

 

[Ku-winda]

Had a very early Lott back in the day when we were making our Lott brass from fire formed 375hh . Shot several hundred 458 Win. thru it early on never saw any erosion with the bore scope we had a the time.

Excellent, thanks!

 

[PeteG]

Good evening - I'm looking for a little guidance on the subject. I just acquired a CZ 550 in 458 Lott and have a few questions about ammo use. I have always heard one of the great advantages to owning a Lott is the ability to use 458 Win Mag ammo if you were to ever get in a pinch. I have also read from some here on the Forum about the ability to load the cartridge down for practice purposes. I have a couple of questions as it relates to both these items. First, is the use of 458 Win Mag ammo relegated only to emergency situations or can it be done on a regular basis without fear of damaging the throat of the barrel. I may not be using the proper terminology here, but when I look at the difference between these two cartridges side by side, I have to wonder if there isn't some kind of "jump" when the Win Mag ammo is fired. If this doesn't create any issues, would it then not make sense to just use the 458 Win Mag ammo (which I have plenty of) in lieu of 458 Lott downloads for practice? Any insights on the matter would be appreciated.

No issue shooting the WM out of a Lott. Shouldn’t have any issue with the throat or performance etc.

A buddy has a 450 ackeley and gets better speed shooting 458wm ammo out of his rifle than when he shoots lott ammo.
Very strange and I don’t understand why

 

[Wyatt Smith]

The win mag has a lot of free-bore to start with. More than the Lott. Look at the chamber reamer dimensions.

 

[Hunter4752001]

My understanding from looking at the SAAMI chamber dimensions is that the the chamber and throat of the Win Mag is considerably greater than that of the Lott (possibly a design feature to make up for a lack of cartridge volume).
The biggest issue to be concerned with is keeping the chamber scrubbed out thoroughly so that fouling doesn't impede the 458 Lott rounds chambering.

 

[dougfinn]

This is sort of like firing 45-70 ammo in a rifle chambered in 45-90. They say there is no harm in doing so, but when I put a few 45-70 rounds through my 45-90, a check with my borescope showed the sharp edge of the 45-90 chamber lip was shaving lead off the bullets and depositing it at the mouth of the chamber. Cleaned up nicely so no harm done, but I won’t try that again with lead bullets. Maybe jacketed will work but I haven’t tried that yet, and maybe never will.

 

[Rafiki]

Good evening - I'm looking for a little guidance on the subject. I just acquired a CZ 550 in 458 Lott and have a few questions about ammo use. I have always heard one of the great advantages to owning a Lott is the ability to use 458 Win Mag ammo if you were to ever get in a pinch. I have also read from some here on the Forum about the ability to load the cartridge down for practice purposes. I have a couple of questions as it relates to both these items. First, is the use of 458 Win Mag ammo relegated only to emergency situations or can it be done on a regular basis without fear of damaging the throat of the barrel. I may not be using the proper terminology here, but when I look at the difference between these two cartridges side by side, I have to wonder if there isn't some kind of "jump" when the Win Mag ammo is fired. If this doesn't create any issues, would it then not make sense to just use the 458 Win Mag ammo (which I have plenty of) in lieu of 458 Lott downloads for practice? Any insights on the matter would be appreciated.

even though this topic has been broached on occasion I wanted to thank for brining it up. I have a project that touches a similar question but with a different cartridge, one that does not exist as yet. I'm working on the reamer diagrams now in the area of the throat so any additional info I can get from your post is and has been quite welcome.

 

[Ku-winda]

Took the CZ 550 out for its maiden voyage this afternoon and could not have been more pleased! Handles great and recoil with the Lott ammo was only marginally more than with the WM ammo - was shooting 500 gr factory rounds out of both. I had different POI between the Lott and WM rounds as expected and cleaned thoroughly as a couple of you suggested, so I think I'm good to go. Next task is to start working up some hand loads with CEB 420 gr Raptors and CEB 450 gr solids using @michael458 formula for success (as noted in a different thread). Thanks to everyone for the input - greatly appreciated!