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.