458 Lott factory chamber vs a reamed from Win Mag chamber

[Nhoro]

I think this variation between factory Lott chamber and reamed from Win Mag Lott chambers is also behind the huge variation in velocity that reloaders report. One guy is getting 200 fps more with no pressure signs while the next guy is already getting pretty severe pressure signs. The two chambers exaggerate any normal reloading variation and people must be even more careful working up loads.

 

[Nhoro]

.458 WM, because you glued bullets in to make a stated velocity, I'm out.

There were reports of this in the 60's. I wasn't born yet, so I will hold my peace. There were also reports of spilled powder all over the Winchester factory floor at the same time period. Dodgy ammo is pretty well documented and all over the internet and I am trying to steer this thread away from that old chestnut. And if anyone is using ammo from the 60's for dangerous game today, then they have bigger problems than the calibre ! Current Hornady ammo is chronographed at 2150- 2170 fps and I have handloads with 480 gr Peregrine solids at 2200 fps-no glue. Many people do not like or mistrust the Win Mag because of it history. I can live with that.

This thread came about because I had my Win Mag reamed to Lott. I did it for 3 reasons1/ Longer rounds feed better in my CZ550 2/Reloading with limited access to powder, I can use South African powder and a wider range of powders in the Lott. I just cant access the powders that Americans have available. 3/ My rifle alreadyhad to go to the smith to have the front sight straightened (it came from CZ soldered at an angle !). So I got the sight fixed,bigger brass bead fitted and the reaming for $100.

In my research, I figured out the difference between a reamed from Win Mag chamber and a factory chamber on the Lott. The diference in those two Lott chambers is almost roughly 1/2 inch or 13 mm of tapered freebore. Both are Lott chambers but that is quite a difference.

 

[fourfive8]

Makes sense because there are apparently two different "standard" reamers for the Lott. Also, separate throating reamers are common and variable so, potentially, most anything is possible. I have no direct experience using the RSA powders but it's my understanding that the powder type availability in RSA accounts for some of the popularity of the 458 Express. So naturally the CZ and long mag actions are good candidates because they can accommodate the Express. Just a side note because a PH friend in RSA has a CZ chambered in the Express.

 

[Forrest Halley]

Now you have me wondering just how big my chamber is...my Lott is a No.1 so I am unconcerned about COAL. I should be long loading ssts or whatever has the highest BC and screaming them out at obscene velocity.

 

[TOBY458]

I'm reviving this thread, as I have recently purchased an R8 in 458 Win Mag. Due to the long magazine length, I can easily load my rounds out to the same COL as the Lott. And with today's monolithic bullets with the multiple bands, it's easy to find an appropriate place to crimp them. For instance, the 450gr Barnes TSX can easily be seated out to Lott COL and still provide plenty of room to crimp the bullet it place. With the long freebore that exists in the Win Mag chamber, I'm still not anywhere near touching the rifling, and I can load the same powder charge as in the Lott. It could probably even be argued that I could load with slightly more powder, due to the freebore that has not been fully used up, even with the longer COL. But I see no reason to for more power than a 450gr bullet at 2250-2350 fps.

 

[ldmay375]

Agree.
After all the recent work that @michael458 did with the 458 Winchester & Lott, I am more than happy with both.

I have a couple of 458 Winchesters currently with standard length magazines, a current SAAMI 458 Lott, and another CZ 550 Safari in 458 Lott / 458 Winchester. I like them all.