458 Win Mag vs 458 Lott....The facts

[TiberiusCassius]

Good morning,

Quickload is well known to have problems with straight walled cartridges like 458 Win/ Lott or Pistole cartridges. It calculates way too much pressure.
Even the designer of Quickload himself states somewhere in the manual that this is a Problem and he also gives instructions how to adjust calculations.
Of course this isnt an excuse to be reckless concerning loading...

Cheers,
TC

 

[fourfive8]

78697 psi! Input error or the QL has a major problem. The whole idea of the Lott vs the WM is less pressure per velocity. You can get decent velocities out the WM but the "cost" is always going to be higher pressure. For reliable function, especially in a DG rifle, high pressure is the enemy. I wouldn't and don't trust any predictive model like QL. Much better to use actual published pressure data along with tangible indicators like brass measurements and chrony readings.

 

[TOBY458]

@Riflecrank this thread I started few years ago might be of interest to you.

 

[Riflecrank]

Ha !
Yes indeed.
QuickLOAD makes no allowance for throat, that is why it is way off,
besides any straight-case issues it might have.

Real world results are also muddied by the fact that many .458 Lotts have varying throat lengths.
The .458 WinMag meeting SAAMI standards has been the same since 1956 unless boogered by maker.

CIP homologation first did it with same throat as SAAMI (and CIP) .458 WinMag tacked onto the 2.8" chamber.
Later SAAMI homologation was for a much shorter throat which CIP then changed theirs to match.

The original wildcat of Jack Lott was a SAAMI .458 WM that was re-chambered with a .450 Watts chamber reamer with no throat so that the residual SAAMI .458 WM throat blended into it.
The SAAMI .458 WM reamer's cutting length is longer than the SAAMI .458 Lott reamer's cutting length.
Such a .458 Lott "like Jack built" should be called a ".458 Lott Special."
It can be loaded to the same maximum COL as the SAAMI .458 WinMag.
It can match the SAAMI .458 WinMag for speed at pressure.
It beats the SAAMI .458 Lott,
just like the SAAMI .458 WinMag does if both are allowed the same COL and pressure.

Another factor muddying the waters is that with factory ammo the .458 WinMag is limited to 60,000 psi by SAAMI (MAP) and 3.340" COL.
The SAAMI MAP for the .458 Lott is 62,500 psi, with COL limit of 3.600".

With those limits in SAAMI chambered rifles, with SAAMI restricted ammo,
the .458 Lott has an advantage of only 50 fps in MV over the .458 WinMag.
And, yes, the .458 Lott has to burn more powder and recoil more vigorously to do that.
It takes a longer bolt throw and will be slower to fire four shots for time,
in a speed shooting (with accuracy) contest.

Win Win Win for the .458 WinMag versus the .458 Loser.

 

[CBH Australia]

@Riflecrank that is quite interesting. I owned a .458wm briefly and read about the shortfall s etc and then wanted a .375anyway but it sounds like you have some in depth knowledge on this

 

[Jefferry404]

I use AA2230 in my Dakota Lott, 2200fps from 24" barrel.
Now, if i was to use h335, this is how i go about using Quickload
First, I fit known data (in this case Hodgdon data) in QL by adjusting Burn rate factor Ba and per
QL developer, weighing factor. This allows one to match the velocity and the pressure to published data.
Below is my QL form for 458 winmag:

I should note the nice thing about the WinMag (other than a great cartridge) is Saami has both cup and psi data, so able to get a good match.
The above is per Hodgdon reload data website.

Then, using that same fitted data above for the 458Lott:

and adjusted the charge to get 2200fps.

Then I shoot 3 rounds and measure with LabRadar, then adjust Ba only to fit the measured velocity
and what the pressure is, it is.
As an aside, Barnes has a load for 500gn solid of 78.0gr h335 for 2245fps at 95% load density.
Since Nosler, Swift and Barnes have smaller max. charge, I would start out 2-5gn lower than above and calibrate.

We know that QL pressure vs case capacity is not a perfect fit, depending on the case capacity differnece. The WM was 95 gn H20 and the Lott, 110. close enough, who knows....
Steve

 

[Hunting Hitman]

Ha !
Yes indeed.
QuickLOAD makes no allowance for throat, that is why it is way off,
besides any straight-case issues it might have.

Real world results are also muddied by the fact that many .458 Lotts have varying throat lengths.
The .458 WinMag meeting SAAMI standards has been the same since 1956 unless boogered by maker.

CIP homologation first did it with same throat as SAAMI (and CIP) .458 WinMag tacked onto the 2.8" chamber.
Later SAAMI homologation was for a much shorter throat which CIP then changed theirs to match.

The original wildcat of Jack Lott was a SAAMI .458 WM that was re-chambered with a .450 Watts chamber reamer with no throat so that the residual SAAMI .458 WM throat blended into it.
The SAAMI .458 WM reamer's cutting length is longer than the SAAMI .458 Lott reamer's cutting length.
Such a .458 Lott "like Jack built" should be called a ".458 Lott Special."
It can be loaded to the same maximum COL as the SAAMI .458 WinMag.
It can match the SAAMI .458 WinMag for speed at pressure.
It beats the SAAMI .458 Lott,
just like the SAAMI .458 WinMag does if both are allowed the same COL and pressure.

Another factor muddying the waters is that with factory ammo the .458 WinMag is limited to 60,000 psi by SAAMI (MAP) and 3.340" COL.
The SAAMI MAP for the .458 Lott is 62,500 psi, with COL limit of 3.600".

With those limits in SAAMI chambered rifles, with SAAMI restricted ammo,
the .458 Lott has an advantage of only 50 fps in MV over the .458 WinMag.
And, yes, the .458 Lott has to burn more powder and recoil more vigorously to do that.
It takes a longer bolt throw and will be slower to fire four shots for time,
in a speed shooting (with accuracy) contest.

Win Win Win for the .458 WinMag versus the .458 Loser.

Can you please provide the 458 win mag load that delivers a 500 grain Cutting Edge flat point solid at 2300 fps?

That would match my Lott data and I could compare.

Thanks

HH

 

[WAB]

Very interesting thread. I don’t load for the Lott, but I have chrono’d federal’s 500 gr TBBC load in my rifle. I’m getting right at 2,300 fps with a 22” barrel. My assumption is that this is about. 150 fps improvement over factory WM loads, but in all honesty I have never tried them.