I am on the verge of ordering a MRC barreled action in .375 Wby. with a 22" barrel as my Alaskan bush rifle (for those of you who are wondering about my Ruger 77 MK II .338 conversion, I have decided to just leave it alone and use it for whitetails; that way I get two rifles instead of one ). I like the idea of keeping H&H ballistics, but in a slightly smaller package that will fit into a plane and not weigh too much. My question is, will repeatedly firing .375 H&H loads (as in several hundred rounds to give myself an adequate supply of brass) cause any damage? I've read on here that frequent firing of .458 Win. in .458 Lott chambers can cause some erosion, so is only recommended as an emergency measure only. Is there any similar concern with firing H&H rounds in a Wby. chamber? Also, would it be okay to use H&H rounds to break-in the barrel, or do I need to fork over $80 for a box of factory .375 Wby. ammo?

There should be no throat erosion from shooting 375 H&H brass.

This is not a good way to get 375 Weatherby brass however as the cases you make will have thin expansion webs as the fireforming will pull metal from there.

Instead buy 375 Weatherby brass new from Weatherby or Quality cartridge. I have been all thru this with a 375 Improved and I am now using Quality's .375 Weatherby brass.

myoder, i think the erosion in the lott and win mag are due to the winmag being shorter where as the H&H and weatherby are the same length. Not sure if this is right.

The H&H cases are slightly shorter than Weatherby , but I don't think it's enough to cause much of a problem.

At any rate , I have not seen anything amiss in fire forming a couple of hundred cases in my Weatherby chamber.

I also don't see the thin web problem Sav 99 refers to . My fireformed cases hold up just fine .

quote:

Originally posted by sdgunslinger:
The H&H cases are slightly shorter than Weatherby , but I don't think it's enough to cause much of a problem.

At any rate , I have not seen anything amiss in fire forming a couple of hundred cases in my Weatherby chamber.

I also don't see the thin web problem Sav 99 refers to . My fireformed cases hold up just fine .

I made a wire feeler gage from a coat hanger wire and I feel inside of every lot of brass before loading it again. The expansion ring or the area of the body of a cartridge just above the base is where case will suffer insipiant or full head separations. When it's almost too late one can see an curved ring on one side of a case. Long before that a ring can be found inside of a case and if it's significant then the case should be discarded.

The 375 Improved that I have had for a long time has the correct headspace on the belt but it and all other belted wildcats are the worst case design as the blown out shoulder pulls metal from the expansion ring as it sticks there and seals the chamber.

Some get around this by fireforming with a bullet seated into the lands but Douglas chambered this barrel in 1969 and to this day I don't know why they put freebore into the throat for a 375 Improved? In any case I cannot reach the lands with any bullet even if they are seated backwards except for the very flat based 285 gr Speer and I have run out of those.

It's really not a lot of fun getting hammered by 100 shots from a 375 just to form cases. Of course some may like that!

I could make brass from 416 Remingtons but then the headstamp would be wrong. At this point the 375 Weatherbys chamber with some feel in my 375 I. chamber. These cases don't need to fireform and fit just right. I may buy some Weatherby brass and see if they chamber easier.

All in all I would never bother with a 375 AI, 375 Weatherby or other oddball 375 again but just go with the regular good old .375 H&H. If thats not big enough then I would go up in caliber and if it's too big then a 9.3mm.

Good luck on your 375 Weatherby.

".375 Basic" or "Basic Magnum" brass is available for considerably less than $60 per box.. (That's un-necked, cylindrical full .375 Mag length belted brass.)

It should be simple enough to form that brass by full-length sizing in your .375 Weatherby die. When doing that you can set the shoulder exactly where you need it, without fireforming.

That will both give you proper headspace without "sucking" brass from anywhere...and will slightly lengthen the case to WBY length as the surplus brass from the necked down area has to go to somewhere.

At least that's the way Roy Weatherby suppossedly did it early on...and probably why the .375 Wby chambers are standardized as very slightly longer than the standard .375 H&H.

quote:

Originally posted by Savage99:
There should be no throat erosion from shooting 375 H&H brass.

This is not a good way to get 375 Weatherby brass however as the cases you make will have thin expansion webs as the fireforming will pull metal from there.

Instead buy 375 Weatherby brass new from Weatherby or Quality cartridge. I have been all thru this with a 375 Improved and I am now using Quality's .375 Weatherby brass.

There's a lot of wisdom in this post...

In my experience the H&H cases will also stretch considerable and eventually separate , if you are loading on the warmish side.

After re-chambering , my fire-formed cases are lasting longer than they did in a plain vanilla H&H chamber . I took great care to make sure the head to shoulder dimention was snug and make sure I am not setting back the shoulder during re-sizing .

For the handloader and experimenter , the Weatherby chamber is quite a worthwhile improvment in my view , with no real downside .

quote:

Originally posted by sdgunslinger:
In my experience the H&H cases will also stretch considerable and eventually separate , if you are loading on the warmish side.

After re-chambering , my fire-formed cases are lasting longer than they did in a plain vanilla H&H chamber . I took great care to make sure the head to shoulder dimention was snug and make sure I am not setting back the shoulder during re-sizing .

For the handloader and experimenter , the Weatherby chamber is quite a worthwhile improvment in my view , with no real downside .

Ditto sdgunslinger.

I use the Hornady Basic brass which is straight cylindrical and neck it down in the .375 Weatherby standard size-decap die, then anneal the necks after trimmingto proper length. No dreaded doughnuts, no problems at all with neck thickness for me. There is enough blank space on the case to engrave your own ".375 WBY" or get it properly headstamped in a hydraulic press.$$$

Of course you will want to put away a couple hundred of the Norma-made .375 Weatherby cases with proper headstamp too. These hold a few grains more powder than the Hornady basic after fire forming both.

The Winchester factory .375 H&H brass shortens considerably when fire formed, and will not be good for other than a dedicated "short brass rifle" if used for reloading. By the time it need strimming, it WILL have had a case head separation.

Good information above.

Yes, the .375 H&H works great in the .375 WBY chamber in a pinch, and is not harmful to the .375 WBY chamber at all.

I agree there is no downside to the .375 Weatherby, that is why I keep only one flyweight (6.75#) .375 H&H for nostalgia sake, and have 3 of the .375 Wby's that weigh 8 to 9.5 pounds bare weight.

The .375 Weatherby will deliver 300 grainers at 2400 fps using factory .375 H&H ammo in a 24" barreled .375 Weatherby chambered rifle.

The .375 WBY will also deliver 300 grainers at 2740 fps, in the same 24" barrel using factory ammo from Weatherby or handloads. Hint: H4350 Extreme.

Note that the old original .375 Weatherby had a sloppy long freebore that was about 3/4" long or more on some poor specimens of rifles.

Must have the new throat: 0.3700" long and only 0.3755" diameter of freebore. MUST HAVE!!!

I would be suprized if there was one big bore rilfe in 10,000 that has been shot enough to wear out or errode the barrel. The only weapons that are suspect of errosion would be something like the M-1 Garand, and only after long and hard service. Big bores are just not shot that much, not even the "Band of Bubbas" have much of a chance at shooting out a barrel. And we shoot them much more than most big bore owners.

Hog Killer

the throat errosion "myth" in the lott with winmag fired in them is probably more to do with poor maintance than "chamber cutting"

in any event, this is not possible with the 375's you mention... as the lott is .35 longer than the winmag..

jeffe