Reamers .458 Lott vs. .450 Watts

[Jim Golden]

Hi Everyone,

So my .458 Lott Enfield project is finally making some headway. Time to ream the chamber.

So my issue is, the standard .458 Lott is 2.80" in overall length, which is .050" shorter than the parent case. Why did Jacques do that? All I can figure is he blew out a .375 H&H case and it shortened 50/1000" as it expanded.

If you take Hornady Basic Belted Magnum brass and run it through the full length sizer, you get a .458 Lott cartridge but it is 2.85" long, which is the original length.

I have read that "most" .458 Lott reamers are actually 2.85" long, which is the same as a .450 Watts, which was basically a Wildcat back then that is identical to the Lott only it's 50/1000" longer. I would like my chamber to be that long.

Was with the 'smith yesterday, and the rental places show the drawings for the actual cartridge, in this case it's 2.80". So, it's not the end of the world. I can just trim cases to 2.80". But, I would really rather have the capability of using the .05" longer case.

For $200 (which is cheap in the scheme of building this rifle) they'd make us a custom reamer of anything we want. But it's $40 to rent a .458 Lott reamer.

Do any of you know if the Lott reamers really are .050" longer than the print? I had read that they were, but would like to know before spending the money. I don't really see me needing more than one .458 Lott so don't know that I need to buy a reamer. But again, I'd like the ability to just resize a case and get the extra couple grains.

Anyone have any experience with this? Where is the best place to get a reamer? I would think the reamer rental place could tell you this, but have not rented one personally before.

Thanks,
Jim

 

[Grumpy gumpy]

I have no experience with either cartridge, but the Watts is the original cartridge that was copied (stolen?)for the Lott design.
gumpy

 

[Huntsmans Bane]

There is no considerable difference between the .450 Ackley and the .458 Lott or Watts (2.85 case). Loading data are quite similar, the small difference in case volume is of the same order as the difference sometimes found between the make of the cases. In "Quickload" data of gr of water are the same.
I think the Lott got its preference by the ease of loading this cartridge and supply of brass. The .450 Ackley needs fireforming with no influence on the efficiency of the cartridge. And some like the possibility of using .458 WinMag in case of emergency

 

[Rez Exelon]

So wait --- when you say Enfield are you meaning a 1917? I have one in 375 H&H that I like, but I wouldn't object if it someday found itself wearing a barrel that said 458 Lott on it. To date, I've done precisely "0" looking into this idea, so I'd be quite curious if you had any tips I should consider!

 

[Jim Golden]

There is no considerable difference between the .450 Ackley and the .458 Lott or Watts (2.85 case). Loading data are quite similar, the small difference in case volume is of the same order as the difference sometimes found between the make of the cases. In "Quickload" data of gr of water are the same.
I think the Lott got its preference by the ease of loading this cartridge and supply of brass. The .450 Ackley needs fireforming with no influence on the efficiency of the cartridge. And some like the possibility of using .458 WinMag in case of emergency

Of them all, the Ackley is probably the best. It's actually got straight neck, and you can fire the other two (three if you count the Winchester in there) in it. But I don't know where you get headstamped brass for it. It's why I went with the Lott.

 

[Jim Golden]

So wait --- when you say Enfield are you meaning a 1917? I have one in 375 H&H that I like, but I wouldn't object if it someday found itself wearing a barrel that said 458 Lott on it. To date, I've done precisely "0" looking into this idea, so I'd be quite curious if you had any tips I should consider!

Rez, I'd say you're about 90% there with this rifle already. The most difficult part is machining the feed rails. It's very tedious. My 'smith said he had to walk away from the project several times as it was aggravating him. But, he took mine from .30-06 to .375 Wby. Yours shouldn't need much adjustment, since they're the same basic diameter already. At any rate, the feed rails are the toughest part. I'd make sure it's bedded really well, although a .375 is no pussycat already so the stock beefup has probably already been done. Might need to change the magazine follower. It took us several tries to get one that worked right on my first project. I'll let you know what my 'smith tells me about machining the feed rails on this one vs the first one. I bought this action from Russ at Whitworth Arms and he already machined the feed rails for .375 H&H. Although, I didn't try feeding one. Look up the A-Square Hannibal. That's basically what we're building here

 

[Rez Exelon]

Rez, I'd say you're about 90% there with this rifle already. The most difficult part is machining the feed rails. It's very tedious. My 'smith said he had to walk away from the project several times as it was aggravating him. But, he took mine from .30-06 to .375 Wby. Yours shouldn't need much adjustment, since they're the same basic diameter already. At any rate, the feed rails are the toughest part. I'd make sure it's bedded really well, although a .375 is no pussycat already so the stock beefup has probably already been done. Might need to change the magazine follower. It took us several tries to get one that worked right on my first project. I'll let you know what my 'smith tells me about machining the feed rails on this one vs the first one. I bought this action from Russ at Whitworth Arms and he already machined the feed rails for .375 H&H. Although, I didn't try feeding one. Look up the A-Square Hannibal. That's basically what we're building here

Great information, I appreciate that! May definitely be worth starting to look up barrels and someone locally that could do the work!

 

[Rez Exelon]

I mean, at the moment I'm sitting on 60ish rounds of Lott and dies and such for it and have been for 3+ years without a Lott going on in life.

 

[Jim Golden]

You need a barrel for that project! Give you a Lott to do! (Bad Dad Joke....)

 

[Nhoro]

458 lott is a factory round and has SAAMI approval/ specs, the others dont. Interestingly, 458 win mag has a longer throat than lott so if you ream a win mag to lott, you have a longer throat and so can load longer brass and copper bullets out a bit., longer col. I would stick with lott as you can gey factory ammo and correct brass for customs officials.

 

[Nhoro]

I thought i should clarify my post. My cz 550 started life as a win mag. My smith was doing some other work and offered to ream to lott for free. The bonus is that i could access different powders in the lott because of more space in the case. The longer throat of the win mag allows me to seat bullets out, on the borderline for lott and get better feeding and a little more space in the case. I dont push the boundaries at 2200 fps with a 515 gr peregrine solid but i am able to lower pressures. The peregrine has driving bands so i crimp it out a couple of bands. I reckon it probably has more capacity than ackley etc in this configuration ?

 

[Jim Golden]

I may just wind up paying the extra $175 and having a custom reamer made that I will own. If I do, I'd rent it to guys on here. Have to see what my 'smith comes back with. Everything I read says all Lott reamers do the extra 50/1000" case length for the full 2.85", but the websites just show the cartridge case length of 2.80. Seems like a lot of hullaballoo over nothing...but I'd really like to be able to use the full length case. Then throat accordingly for a 550gr with freebore. Let ya all know!

 

[Nhoro]

Or do the sums on a win mag reamer followed by a lott. That might be the same thing. And it seems a headspace gauge would answer your questions. Surely measuring the go and no go gauge would give you the chamber length ?

 

[Inline6]

Or do the sums on a win mag reamer followed by a lott. That might be the same thing. And it seems a headspace gauge would answer your questions. Surely measuring the go and no go gauge would give you the chamber length ?

Headspace is measured off the belt.

Personally I'd just run the lott and not worry about the rest. That little length is not going make a difference. You are not leaving anything on the table IMHO.

 

[Jim Golden]

You're right. It would just save me trimming cases that I form from Hornady Basic Belted Magnum

 

[fourfive8]

No matter what chamber length you end up with, cases will need to be trimmed to uniform length and on regular basis depending in pressures, brass softness and sizing. I did a similar build and used a reamer that was made according to 450 Watts specs. I trim my cases to just under the max listing for the Lott length. About a .005” +/- length variation seems normal for the industry. Seems like ordering the Watts reamer would be simplest. Measure the resulting chamber length with a plug gauge then trim cases to .005-.010 less than chamber length if using full length Watts brass. Or just use Lott brass and trim to consistent length. Additionally, you can then also shoot 458 Win Mag in a pinch in a Watts chamber. Carts that are slightly short in a chamber with a longer throat have a slight advantage for preventing high temperature/over pressure issues.

 

[fourfive8]

Short follow-up. Here is what I use to measure exact chamber length for all my rifles. Only has to be done once. They are specific by diameter. Simply trim about .25" off a case resized enough to hold plug with small amount of friction, insert plug just enough to hold it in case, carefully chamber shortened/modified case with plug, extract, measure length. Simple and accurate. Firing a cartridge in a chamber that is short for the case, even by the smallest amount, can run pressures up to dangerous levels. These gauges can also be made DIY fairly easily with basic tools.

Sinclair/Brownells examples

 

[John P.]

When I built my first Lott (Maybe 1988 or so) I could not find any brass. Did some work for a retired guy from Alaska, he lived about 10 miles from my place on Washington's Olympic Peninsula. He just happened to have a 100 450 Watts cartridges and cases. After some horse trading I wound up with them.

So my reamer was ground to Jack Lotts specs prior to this, and the Watts cartridges worked fine after a little trimming of the cases. Later I sent the reamer back and had it ground to full length H&H specs. Reason being so the chamber would take any and all full-length cases. Allowing for full length basic brass, of which I later purchased 100 Norma cylindrical H&H cases when they became available.

Along the way I purchased 100 rounds of Hornady brass, properly head stamped 458 Lott.


So why did Jack Lott make his original 0.050" shorter?? Because he fire formed 375 H&H brass in a first chambered rifle with a squib load. When trimmed a bit the case wound up 0.050" shorter.

This is explained in his article in the first edition of "Big Bore Rifles". I have both editions.

3 shots, full house 500 grain loads, 100 yards. It would have been a one holer if I did not flinch on the last shot. 3 shots was enough!!

I later changed the front sight blade to lower the impact point.

 

[John P.]

Do any of you know if the Lott reamers really are .050" longer than the print? I had read that they were, but would like to know before spending the money. I don't really see me needing more than one .458 Lott so don't know that I need to buy a reamer. But again, I'd like the ability to just resize a case and get the extra couple grains.

I will take a look at my reamer drawings and see.

You can always call the reamer maker.

 

[John P.]

From the PTG drawings, case lengths

458 Lott 2.854

450 Watts 2.8643



My Lott reamer 2.865

Cases

458 Lott Bell brass 2.783

Norma basic H&H brass 2.835

So, take your choice. Main thing with a big bore "stopping rifle" chamber is it must take any and all cartridges you can stuff in it, even those tarnished unknown 458 cartridges you find under the Land Rover seat. A cape buff will not give you a second chance!

Before you order a reamer you should have a dummy round with a bullet properly seated. Send it to your reamer maker for a good fit.