jjs,

In the Lott, max powder charges usually result in a compressed load, especially with Barnes bullets which tend to be very long. As long as the bullets do not touch the rifling lands, and as long as the rounds feed all the way from a full magazine, then there will be nothing wrong with exceeding published max cartridge length for the Lott. Keep in mind that the CZ550 is a Super Sized action meant to fit the 416 Rigby which has a 4.10" overall length, so you have plenty of room in there. If you were working with a pre-64 model 70, overall length would be more critical.

My pet load for the 458 Lott: 84.0 grains IMR4320 with 500 grain Woodleigh. Some guys have gone up to 88.0 grains, but I think that is pushing it.

The standard max cartridge overall length for the .458 Lott is 3.600". But your rifle may differ from the standard.

It's best to measure this in your own rifle, as there are bound to be variances between rifles.

Take an unprimed, uncharged Lott case and cut a slit down one side from the case mouth back about .5" (a Dremel cut-off wheel works nicely).

Seat your bullet into the case so that it is barely inside the case mouth, then feed it into the chamber. Close the bolt, then open it and remove the dummy round.

You should see the marks where the rifling engaged the bullet; the COAL measurement you are looking for (if I understand you correctly) is from the case head to those marks. Of course, you wouldn't want to actually load that way...

George

GeorgeS:

Thanks for the advice.

500grains:
I have been loading to that length 3.6". The problem I have is with the longer bullets (500 grains) using Barnes TSX and working up to or near max powder charges...it becomes very difficult to seat to less than 3.65" or so.

I am not sure if it is the set up, bullet and load, or the Hornady dies. Those dies seem to neck the case mouth and about 1/3+ of the case to somewhere in the range of .430". I am looking forward to Redding bring out the 458 Lott dies in the near future...may be that will help! After using the Hornady dies with the Lott I do not plan on purchasing another set of Hornady...However, I will say their 458 Lott Brass seems to be of very good quality.

In the interim I will use GeorgeS approach to determine the max overall length of the cartridge in my rifle with the hope that I can seat out to about 3.650" or so...

Thanks again, jjs

Wanted a starting point or if any of you guys have knowledge concerning the max. overall cartridge length of the 458 Lott in a CZ 550 Safari?

I am not concerned as to the magazine length as that is not the issue but the length to reload safely ie not touching the rifling.

Appreciate you assistance...

jjs