I am thinking about putting together a .458 of some sort on something smaller than a rigby sized action (like the CZ 550).

I absolutely love the slick feeding of .375 H&H rounds in pre-64 Model 70's and that the pre-64's hold 4 down with no modification or drop belly necessary.

Questions:
1. Do pre-64 M70 actions that started as .300 H&H/.375 H&H hold 4 down in .458 Lott, .450 Watts, .450 Barnes Supreme or .450 Ackley without any modification necessary? Or is there not enough taper on the various "long" .458's to get 4 to fit?

2. The pre-64 box is ~3.6" versus ~3.62 for the Classics. Will the 3.6" box limit bullet choices or create feeding problems in a .458 Watts/Ackley? Is the cannelure on most .458 bullets such that I will have problems going with a 2.85" case rather than the Lott (I would prefer to go Watts or Ackley if on a pre-64)?

3. Does the .416 Barnes Supreme or any wildcat > .4 based on the .375 H&H case maintain the original body taper? Or are they all improved like the more recent developments (e.g. .416 Rem Mag, .400 H&H)?

I tried searching the forum but didn't have much luck. Of course, the simplest thing would be to just re-barrel my beater stainless Ruger M77 MKII in .338 to .458 Win Mag and be done with it...

375-404 is close to untapered I believe.

404-375 just makes sense--


http://forums.accuratereloadin...6521043/m/6171003602



http://forums.accuratereloadin...6521043/m/7481084602


D'Arcy and Boomie did good on this one---I would go with it over the .400 H&h anytime, and because of availability of actions and brass probably over the 404 J

quote:

Originally posted by myoderru03:
I am thinking about putting together a .458 of some sort on something smaller than a rigby sized action (like the CZ 550).

I absolutely love the slick feeding of .375 H&H rounds in pre-64 Model 70's and that the pre-64's hold 4 down with no modification or drop belly necessary.

Questions:
1. Do pre-64 M70 actions that started as .300 H&H/.375 H&H hold 4 down in .458 Lott, .450 Watts, .450 Barnes Supreme or .450 Ackley without any modification necessary? Or is there not enough taper on the various "long" .458's to get 4 to fit?

2. The pre-64 box is ~3.6" versus ~3.62 for the Classics. Will the 3.6" box limit bullet choices or create feeding problems in a .458 Watts/Ackley? Is the cannelure on most .458 bullets such that I will have problems going with a 2.85" case rather than the Lott (I would prefer to go Watts or Ackley if on a pre-64)?

3. Does the .416 Barnes Supreme or any wildcat > .4 based on the .375 H&H case maintain the original body taper? Or are they all improved like the more recent developments (e.g. .416 Rem Mag, .400 H&H)?

I tried searching the forum but didn't have much luck. Of course, the simplest thing would be to just re-barrel my beater stainless Ruger M77 MKII in .338 to .458 Win Mag and be done with it...

1. If they hold 4 down of 375, they will hold 4 down of the Lott/Watts/Ackley.
2. The max length for all mentioned is 3.6", most cannelure lengths fall short of this.
3. All the wildcats have less taper, but, this should not pose a problem. I went from 375H&H to 375 Weatherby without an issue.

It sounds very viable to me with little to no mods needed.

Cheers.

The Lott case is much larger in Dia than the 375 2.400 ahead of the case base. The Ackley version has an even larger Dia. Only 3 rounds will fit in the Pre 64 or current Mod-70 OEM magazine with all 3 of these case designs.

Both have 3,625/3.630 ID lengths inside the magazine box. The factory Lott rounds are loaded to approx. 3.585 + or - .010

South African PH Campbell Smith carried one of the 1st Watts reamers to SA over 3 decades ago and has used a Watts built on a Pre-64 as a back up rifle ever since. He settled on the Older Steel Jacketed 500gr Hornady FMJ's and 500 Gr A-Frames. The rifle feeds 100% but has been modified to do so and only holds 3 down. I have seen him use that rifle in Bots and anyone thats says those older Steel Jacketed Hornady's will bounce off Ele's is full of prunes in his opinion and he has shot a lot more of them them into Ele's than into test media.

The Pre-64 Lott conversion is not seamless as the OEM factory magazine as the 300/375 is too narrow for the Lott case at the forward rib position inside the magazine and allows all the Lott rounds to usually slip from under the rails when the bolt is racked smartly on a full magazine and drops the loaded rounds around you ankles. Those 2 ribs should be removed to allow you the required width, some enterprising smiths pound them flat distorting the box and racially lengthening the magazine or retro fit a newly manufactured magazine, which then requires a wider follower, etc. I have built more than 1 Lott on both Mod-70 versions.

If you want a 40 Caliber the 404-375 H&H will work in a Pre-64 Long 300/375 action and hold 4 down and 1 up with little bullet ramp work. Do not expect 2400 fps with a 400 gr bullet unless Ray is loading for you. 2265 TO 2300fps is the sweet spot and max.

The older 602 Brno 458 Win can be reamed to the Lott, Watts or Ackley in a fairly simple conversion step and you can keeping shoving shells into one of those until sun down.

Thank you for the information!

That is what I was afraid of, but it is good to hear confirmation that the Lott/Ackley/etc. would not do 4 down and/or feed without modification due to the lack of taper. I will just use my extra pre-64 H&H action for either a .350 G&H or a .404-375H&H and then use a Classic Model 70 (or some other action) for a .458 of some sort.

check your PM's.

Rich

The 404-375 HH is a pretty "slick" cart and hits your parameters right on the primer. A couple variants would be a 400-375 HH with a simple neck up and if my calculus is right about a 5 thou ghost shoulder that would barely be seen or felt giving you an incredible range of bullets to play with obtaining those same qualities. If you wanted to be a cast bullet guy and keep the gas check in the neck on 400 grain bullets and do not mind replacing the barrel vs rebore option because of chamber clean up (unless your donor gun is a 300 HH) than the 400-300 HH would provide an elegantly long neck with that ghost shoulder while keeping the gas check in the neck. I know there already is a 400/375 HH created by HH but that is quite different. Having three identical rifles for reasons of muscle memory/training/cool factor in 300 HH, 375 HH and one of the above mentioned variants to have slick feeding rifles for up to 200,300 and 400 grain bullets would be quite the gun battery. Thoughts?

Another easy option is the 375 Weatherby. Just rechambering of your current barrel is needed. Allows you to shoot those new Woodleigh 350g HD softpoints at 2550 fps. That puts you at the 5000 ft/lbs level for energy and great penetration (and you can still shoot factory 375 H&H ammo through it!) By comparison the standard load for the 404 Jeffery is just over 4000 ft/lbs (400g bullet at 2150 fps ) with about the same Taylor KO factor. The 458 Win (500g bullet at 2100 fps) is just under 5000 ft/lbs of energy with 35% higher KO factor.

Just a thought.

Here's one of mine, just completed on an original pre-64 M70 458. It was opened up to 458 Lott during the build.

As much as I like the 404 Jeffereys, it would seem to me the 416 Remington or Ruger would be every bit as good and less expensive than a 404/375...

I've used both the 404 and 416 Rem on buffalo and what not, and there is absolutely no difference other than nostalgia, but like many others I would not have admitted that some years ago....

The .458 Lott makes a lot of since in a mod. 70 but Im not interested in the extra recoil in my golden years..

A 400 gr. bullet at 2400 FPS is where I load both the 404 and 416 and so far Im still around at 81, hell I can toss a rock 2200 FPS..

I don't know where a lot of this imaginary information comes from, but I have built a Ackly on a pre- 64 .375 H&H win action that works perfectly and it wasn't hard. If you want to come to Vegas your welcome to shoot it. None of the mods needed are difficult for any reasonably competent gunsmith or skilled amateur. Mine turned out great and is a really nice gun to carry. Extremely accurate too. The mag box mods are trivial and I did the barrel treading, coning, extractor cut and head spacing myself. A little feed ramp work was all it took to get it to feed perfectly! How about empty cases upside down? That good enough? I've always felt this was a really nice conversion. As I've said before a Ackly will drive a 500 gr bullet to 2400fps any day and every day! I just like the whole concept especially in a pre- 64 win!

I really like my OM 70 in 458/375 RUM. I can use either RUM brass (if Remington ever makes any more) or my stash of 404J BELL brass.