Zastava 458 WM action length

[fourfive8]

I, personally, would not bother rechambering these days.
Especially so if the magazine of the particular rifle allows the loaded Win mag rounds to be loaded out to 3.6 o/a, then at the same pressure the Win mag is 50 - 80 fps behind the Lott.

Most people say that the Lott runs at a regular 2400fps for the 500gn slug.
I say bullshit.
A lott loaded to 2400fps will be at it's max pressure threshold and something I do not want to be out in the field with, sorry.

I have owned and hunted with three different Lotts over a period of over thirty years.
My very best chronographed loads that I could actually hunt with were in the 2280fps region.
In a rifle that allows loading the Win mag to 3.6 o/a it is not difficult to get 500gn pills up to 2200fps and some change. F/all difference.

More important to me would be the pill that you are loading, especially so if it is being intended for thick skinned game hunting.

The cartridge stay in the chamber.
The projectile does the damage !

Lot of theory there with the 50 to 80 fps difference between the WM and the Lott at standard pressures with loads designed for hunting in all conditions, including high temps!! I won't call BS but... there seems to be a couple of details left out that need to be accounted for.

I assume the theory presented is: by lengthening the 458 WM OAL, the volume would be increased allowing the larger capacity of the case to operate at lower pressures in achieving comparable velocities to larger/longer cartridges with more volume ... like the Lott.

Loading a 458 WM out to 3.6" OAL would allow for about a 1/4" neck engagement on an average 500 gr RN cup and core bullet with the case mouth no where near the crimp groove. That little detail was not mentioned, which it is a big detail for a Dangerous Game load! Minimal neck tension and no crimp into crimp groove! That's just asking for significant bullet setback in the magazine from recoil along with the resulting serious problems associated with that setback!

The other detail left out is about loading a 458 WM to 3.6" OAL and trying to chamber it in a 458 WM chamber if the chamber didn't have the standard SAAMI 458 WM long free bore throat (no matter if the action length, including magazine length was 3.6" or not). Potentially, there could be a huge problem with jamming the bullet into the lands and leaving it there when unloading a loaded round or a large, unpredictable pressure spike from having the bullet jammed into the lands when fired. Need to make certain that throat/free bore is long enough for the longer OAL.

Here's a pic demonstrating the concept of minimal neck engagement and not crimping within the bullet's crimp groove - shows the seating depth of an average 500 gr 458 RN bullet into a 458 WM case to yield a 3.6" OAL.

I'd be happy to consider the premise of loading a 458 WM to 3.6", but the two details just described need to be sorted first.

 

[CoElkHunter]

Lot of theory there with the 50 to 80 fps difference between the WM and the Lott at standard pressures with loads designed for hunting in all conditions, including high temps!! I won't call BS but... there seems to be a couple of details left out that need to be accounted for.

I assume the theory presented is: by lengthening the 458 WM OAL, the volume would be increased allowing the larger capacity of the case to operate at lower pressures in achieving comparable velocities to larger/longer cartridges with more volume ... like the Lott.

Loading a 458 WM out to 3.6" OAL would allow for about a 1/4" neck engagement on an average 500 gr RN cup and core bullet with the case mouth no where near the crimp groove. That little detail was not mentioned, which it is a big detail for a Dangerous Game load! Minimal neck tension and no crimp into crimp groove! That's just asking for significant bullet setback in the magazine from recoil along with the resulting serious problems associated with that setback!

The other detail left out is about loading a 458 WM to 3.6" OAL and trying to chamber it in a 458 WM chamber if the chamber didn't have the standard SAAMI 458 WM long free bore throat (no matter if the action length, including magazine length was 3.6" or not). Potentially, there could be a huge problem with jamming the bullet into the lands and leaving it there when unloading a loaded round or a large, unpredictable pressure spike from having the bullet jammed into the lands when fired. Need to make certain that throat/free bore is long enough for the longer OAL.

Here's a pic demonstrating the concept of minimal neck engagement and not crimping within the bullet's crimp groove - shows the seating depth of an average 500 gr 458 RN bullet into a 458 WM case to yield a 3.6" OAL.

I'd be happy to consider the premise of loading a 458 WM to 3.6", but the two details just described need to be sorted first.

View attachment 311915

I don't know what it would cost to re-bore a WM to a Lott, say in a CZ 550? But with the additional gunsmithing required to do this in a Zastava type action, I wonder if it really is cost effective? I get the feeling from reading some of this here and on other threads, when trying to get too "exotic" with some modifications, bad things can happen, especially with feeding and function problems? I guess generally this would only be a nuisance, unless your hunting something that can kill you if your rifle doesn't function properly?

 

[Dale Wade]

Yes. CZ 550's are a great deal. 416 Rigbys are going on the major gun auction site for are $1200 - $1300 if I remember correctly. Too bad 404 Jeffery guns are not more available.

 

[SpruceBug]

Looking at another 458 lott is the action length of the zastava 458 WM long enough to rechamber or is it a blown out standard length action

Any update on this project? I have a 300wm Zastava LK M70. I know it might require some modification and a heavier stock, I want to rebarrel to 458Lott and worse case scenario, can you shoot 458 win mag through a 458 Lott chamber with the extended freebore?
Seems safe to assume a 45wm in a lott chamber will have some bullet miss alignment.

 

[Milan]

Any update on this project? I have a 300wm Zastava LK M70. I know it might require some modification and a heavier stock, I want to rebarrel to 458Lott and worse case scenario, can you shoot 458 win mag through a 458 Lott chamber with the extended freebore?
Seems safe to assume a 45wm in a lott chamber will have some bullet miss alignment.

The zastava being a standard length action, I'd just do it as a 458 WM.

 

[rifletuner]

I have a Zastava action that was a 375H&H which was the basis for a 416 Rem build. You could definatly make a 458 Lott work on the action. If it was originally a 458 Win, than it would also need a longer magazine box.

I have seen a 500 Jeffery on a Zastava action, so a lot would definitely not be pushing the boundaries.

Having said that, I agree with the others that suggest its not worth the effort. The 458 Win is a good option and so close it just isnt worth it.

 

[rdog]

The Zastava 375 action is the same as the 458 action. They cut back the feed ramp about 0.200" to accommodate the longer round. On the 458 the rails are opened up more to accommodate fatter bullets up front. You could start with either action for the Lott. On the 375 you might have to widen the front of the magazine box and rework the feed rails. On the 458 you will certainly have to lengthen the magazine box and move the feed ramp forward. The rails nught be ok as is. Here are some measurements. Please note that Zastava did not lengthen the throw of the bolt rearward to gain the additional clearance. It is all taken from the front of the action.

Here are the dimensions for the .458 Win Mag.
.458 Winchester Magnum
Bolt face to feed ramp: 3.581"
Below is the width of the opening between the feed rails as measured going forward from the bolt face
0.500" from bolt face width is .627"
1.00" from bolt face width is 0.620"
1.500" from bolt face width is 0.617"
2.000" from bolt face width is 0.620"
2.500" from bolt face width is 0.615"
3.000" from bolt face width is 0.571"
3.300" from bolt face width is 0.528"
Forward of that you enter the radius of the feed ramp

Magazine Box:
Length: 3.404
Width at Rear: 0.900
Width 3.300" from rear: .721
Forward of that you are in the radius of the front wall

375 H&H
Bolt face to feed ramp: 3.78""
Below is the width of the opening between the feed rails as measured going forward from the bolt face
0.500" from bolt face width is .611"
1.00" from bolt face width is 0.619"
1.50" from bolt face width is 0.612"
2.00" from bolt face width is 0.612"
2.50" from bolt face width is 0.612"
3.00" from bolt face width is 0.588"
3.25" from bolt face width is 0.577"
3.50" from the bolt face width is 0.559"
Forward of that you enter the radius of the feed ramp

Magazine Box:
Length: 3.67"
Width at Rear: 0.916"
Width 3.500" from rear: .708
Forward of that you are in the radius of the front wall



The bolt does not go any further back than on the 458 Win Mag. It appears that Zastava gained all of the additional clearance strictly from the front of the action. Distance from the rear face of the recoil lug to the edge of the feed ramp on the 458 action is 0.881" and on the 375 action it is 0.631"
Top

That is very good info.

 

[Milan]

I have a Zastava action that was a 375H&H which was the basis for a 416 Rem build. You could definatly make a 458 Lott work on the action. If it was originally a 458 Win, than it would also need a longer magazine box.

I have seen a 500 Jeffery on a Zastava action, so a lot would definitely not be pushing the boundaries.

Having said that, I agree with the others that suggest its not worth the effort. The 458 Win is a good option and so close it just isnt worth it.

Yup. I had a Mark X in .375 and yes, just like Mauser 98 action can be made to accommodate the longer cartridges, I'm sure M70 can be made to work with the .458 Lott. I just thought starting with .300WM one, .458 WM might be less work - well at least in the magazine and ramp area. As another post above mentions, lot of work is usually needed (magazine, ramp, rails, etc.). But that is how factory did it. Here one might be able to not modify the feed ramp, but rather just the rails as the length of the cartridge might allow stock .300WM magazine and ramp. If you start with an M70 in .375 H&H, then might as well shoot for .458 Lott.

 

[cajunchefray]

That is very good info.

Excellent detrailed information from R Dog. Thank You.

Based upon my rifles, the Interarms Whitworth .458 Winchester Magnum has the same Magazine Length as the .375H&H.

Extended chambering, with space milled from the feed ramp.
If W.J. Jefferey, Westley Richards, and Holland and Holland did it, rifles lasting decades, then I think it's OK.

I recently checked this magazine length, (3.58") and angle configuration by feeding .375 H&H dummy rounds through the Whitworth .458 Winchester Magnum.

Worked like a champ.

I would not hesitate to rechamber a .458 Win Mag to .458 Lott, accounting for the chamber leade and free bore and throating, like the .458 Winchester MAGNUM.

 

[Daga Boy]

Good point on the CZ vs. the Zastava. My Whitworth.375 is lighter and the action smoother than my CZ .458 WM. But I really love my CZ. BUT, I don’t know about a Lott in the Zastava action? It would work, but I would stay with the beefier, heavy CZ in a Lott? But, I’ll shoot anything ONCE to see if I like it! If I don’t like it, theres always Toby 458 to sell it to. Ha! Ha! Ha!

It's a standard length action. I doubt you will get Lott ammo to feed reliably. The gun is also way too light for Lott loads.