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| The .458 Watts / .458 Lott |
| Current African Cartridges |
| Cal Pappas |
| ~To all intents and purposes the .450 Watts and .458 Lott are the same cartridge, and originated in the early
1950’s in the USA. Essentially, the .450 Watts is a .375 case blown out to accept a .458 diameter bullet. This gives
a slightly tapered case of approximately 2.85" length. Original loading data developed by the noted gunsmith, P.O. Ackley,
lists the .450 Watts as driving a 500 grain bullet at 2500fps.~ |
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| The standard big game cartridges L - R .500 Nitro Express, .470 Nitro Express, .458 Lott, .458 Winchester. |
A .450 Watts short magnum was developed with the case shortened to 2.5" and loaded to more or less duplicate the British
.450 Nitro Express. This latter cartridge was subsequently adopted by Winchester as the .458 Win Magnum in 1956. Mr Ackley’s
loading data seems to have been a little enthusiastic for both cartridges, and the .458 Win suffered, particularly when it
was found necessary to download to reduce the dangers of powder clumping. What Winchester had hoped was that their new .458
would become the industry standard to replace the host of British flanged rounds that all delivered a .450-.476 diameter bullet,
weighing from 480-500 grains at a velocity of between 2125 and 2175 fps. The concept was a good one. The British double rifles
were becoming too expensive, and in any case American hunters going on Safari preferred bolt actioned rifles. As Winchester
intended, the .458 rapidly established itself as the new industry standard. The 500 grain steel jacketed solids gave good
penetration, cheap rifles were readily available, and the .458 gave better ‘knock down’ effect on elephant than
the only other viable alternative, the .404. The .450 Watts Magnum virtually died: after all, who needed more than a .458?
By the mid 1970’s plenty of people could see a reason for something more than a .458. Winchester had been forced
to significantly download the .458, and terminal performance suffered. The new loads produced only around 1950fps in most
sporter length barrels, and although with a good bullet penetration is usually adequate at this velocity, the old knockdown
effect was noticeably less. In the meantime, Jack Lott had re-invented the wheel, so to speak, with necked up .375 cases to
form a full length .450 magnum. Essentially this was the same cartridge as the much earlier Watts, but with a longer throat,
and (depending on how the cases were made up) a case .05" shorter. It was Jack Lott’s version of this wildcat cartridge
that became standard, since as a well known gun writer he was able to publicise it better. Professional hunters, game wardens,
tsetse control officers and others who had cause to regularly shoot big game and seldom under favourable circumstances went
for the .458 Lott in a big way. Its knock down effect on elephant was noticeably better than even the hottest loaded .458
Winchester. Many Professionals reckoned that the new Wildcat was superior to even the .470, and possibly as good as the .500
in terms of knock out/knock down effect. Using Softpoint bullets on lion, the .458 Lott is in a whole different class to the
.458 Win due to the higher velocity and the cat’s sensitivity to hydrostatic shock (to get a proper “explosive
wound” effect due to hydrostatic shock, the velocity of a bullet needs to be above 2200fps). Sensibly loaded to moderate
pressures the .458 Lott will drive a 500 grain bullet at 2300fps. You can get it higher, but then sticky extraction becomes
a risk on a hot day and that just isn’t worth it.
Converting a .458 Win to the .458 Lott is simple, provided the action is long enough. Many .458’s are built on standard
length actions, and converting them to take a magnum length cartridge involves changing the magazine box and quite a bit of
machining by a very competent gunsmith. Many .458’s are, however, built on a magnum length action and these just beg
to be converted. Here conversion simply entails inserting a correct conversion reamer (note a conversion reamer cannot alter
the head space unlike a poorly used chambering reamer) into the chamber and turning it until it seats. It's almost simple
enough for any good home hobbyist to manage. The only catch is that the feed rails may require a little professional filing
to get the longer cartridge to feed flawlessly from the magazine. |
| stopper par-excellence; .470 NE, the standard double rifle cartridge by which all other dangerous
game rounds are judged; .450 Ackley, its good ballistics are compromised by pressure problems; .458 Lott, duplicates the knock
down power of the .470 - its what the .458 Win was meant to be; .458 Winchester. |
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On re-chambering, there seems to be quite a bit of confusion over the minute variation between Watts and Lott. All the
modern chambering reamers make the chamber long enough to accommodate a case 2.85" long, and any difference is simply in the
throat dimensions. It wasn’t always like that, and I have frequently seen rifles converted to .458 Lott in South Africa
that were only made to accommodate a case 2.80" long. This is a real problem when trying to use modern A-Square Factory ammo,
or even most reloads. The front of the chamber pinches the round in the area of the crimp. Chambering of the longer rounds
is frequently possible but the pressures are through the roof as the crimp cannot unfold to release the bullet (a bit like
firing 2 ¾" shot gun shells in an old shotgun with 2½" chambers, something has to let go sooner or later). Make sure when
you order the conversion you specify that you will be using the longer cases:- I cannot emphasise this enough, just be sure,
very sure. On throat dimensions, Jack Lott got it right. The longer throat lowers pressure and that is definitely required
in a dangerous game rifle. Consequently, I don’t know why anyone will order a rifle chambered for the short throated
Watts anymore.
Apart from the obvious improvement in terminal performance, what else does the Lott have going for it? Firstly one can
still fire standard .458 Win ammo in the longer chamber without any danger and very little loss in performance. This means
one can practice with cheaper ammo, and if push really comes to shove out in the middle of nowhere, you can probably scrape
together a few .458 Win rounds from the local game warden or a neighbouring hunter. Also anything the .458 Win can do the
Lott can achieve and more. Its easy to download to standard .458 Win ballistics for practice (especially if you don’t
like recoil) and yet have full throttle rounds for the real thing. Most .458 Lott’s also shoot cast bullets remarkably
well for even cheaper practice. The .458 Lott also has a tapered case, just like the .458 Win (and unlike the .450 Watts)
which improves extraction, which is particularly important in a dangerous game rifle. And finally, many rifles with magnum
length actions (like the Bruno) feed the longer Lott round much, much more reliably than the short .458 Win. The disadvantages?
Well the Lott has significantly more recoil than the standard .458 in full house loadings. If your rifle stock isn’t
properly bedded, its going to crack in short order. Zeroing your Lott with full power loads from the bench or even sitting
constitutes a “significant emotional event” as far as I am concerned. It’s a long way from my idea of fun,
and something I will go a long way to avoid in future. In practice though this isn’t really a problem. From the bench
you shoot standard .458 Win loads, which whilst hardly a pleasant way to spend an afternoon, is at least within my recoil
tolerance level. You then do the final check with full power loads from the standing position. ( Note: if you are working
up your own reloads and have to shoot from the bench, unless you are one of that rare breed who have a very high tolerance
level to recoil, find a few friends who want to shoot a “real” rifle and con them into doing it). From the standing
position (which is how one will almost invariably shoot in the bush) the recoil is not noticeably different from a .458 Win
or .416. I doubt that you could actually tell the difference.
Is the conversion to .458 Lott worth while? Very definitely! Its everything the .458 Win wanted to be and more. Any rifle
with a long enough action to take the Lott should be converted. It is the bolt gun’s answer to the .500 Nitro and the
most readily obtainable “stopping” cartridge on the market today.
Finally, and with much caution I publish a few reloads that have worked well, in the test rifle. Case head expansion was
well within limits and there were no other pressure signs. This does not mean that they are safe in your rifle. Back right
off and work up slowly.
Please Note. The charges listed below are, in my opinion MAXIMUM. Increasing the charge gave either measurable case head
expansion and occasionally sticky extraction, or simply resulted in no worthwhile increase in velocity (eg 84grains of S321
behind the Speer bullet gave an average of 20fps less than 83 grains). Neither the author, nor the publisher can be held responsible
for the use of this data. Having said this though, the .458 Lott is a very forgiving cartridge to load for, no sudden pressure
peaks, no erratic burns, just like the .458 Win but with more case capacity to play with.
| .458 Lott (2.85" chamber) |
| Bullet |
Powder |
Charge |
Average Velocity |
500 grain Hornady
Steel jacketed solid |
S321 |
82 grains |
2312fps |
475 grain PMP
Monometal solid |
S321 |
78 grains |
2293 fps |
400 grain Speer
standard soft point |
S321 |
83 grains |
2396 fps | |
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