Would I run into any problems sizing up .375 H&H brass or .458 Lott brass down to .416 RM?

Thanx in advance Hip!

A. Necking up the .375 H&H to .416 will shorten it, and fire-forming it to blow out the shoulder will will further shortened the brass.
You want it to be 2.850" max, 2.840" minimum.

Firing WW .375 H&H brass in a .375 Weatherby Magnum chamber shortens the brass about .020", from 2.850" to 2.830".

Your .416 RemMag will shorten it more than that by the double-whammy of neck up and blowout.

And there will be some minor thinning of the neck wall thickness at Neck-2 (case mouth),
and there may be a "dreaded doughnut" at the bottom of the neck (Neck-1) to deal with by inside reaming after fire-forming.

When I neck up .338 Lapua Magnum brass to .375 Twister, I have to deal with dreaded doughnut,
where the previous thicker shoulder of the brass has now become Neck-1 of the wildcat.


B. The .458 Lott brass starts off .050" short and has to be folded into a shoulder and necked down, maybe compensating effects,
but you are still going to be short after fire-forming, I reckon.

All of the above may be of no consequence, and work fine except for slightly short brass you won't have to trim anytime soon.

Try either and see what works best for you,
hard to cause mischief either way.

C. The best way to make brass if you cannot find .416 Rem.Mag. brass is to get Hornady or Norma H&H basic cylindrical.
That starts off long: 2.868" for Hornady.
When I necked that down to .410-caliber-bullet-acceptance, it grew to 2.883".

Neck it down to .416 Rem Mag in one pass and trim it to 2.840"-2.850" and fire-form it.
It will probably end up very close to 2.850" which is your goal.

D. I have formed .416 Barnes Supreme brass by simply popping off .375 H&H factory ammo in the chamber of this old proprietary round from the 1950s.
It was the .416 Remington Magnum before George Hoffman, by Fred Barnes of the Original Barnes Bullets.
My trick made for short brass.
I would have to dig that "WW .375 H&H" headstamped brass for my .416 BS out of a footlocker to measure it,
to say how short.

Fred Barnes used to supply cylindrical H&H basic brass with "Barnes Supreme" headstamp to use in forming both the .416 BS and .450 BS.

Method "C." above is the best method if you must form some .416 Remington Brass.
I never have had to, just .416 Barnes Supreme, granddaddy to the .416 Remington Magnum,
if the .416 Hoffman is the mother of the .416 Remington.

Squirrel season is coming ... GOR
Rip
.

Or you can just buy a box of 50 Hornady cases at Midway USA for $51.49 (on sale right now). For ~$1/case, why bother trying to make them out of something else?

quote:

Originally posted by jlabreck7316:
Or you can just buy a box of 50 Hornady cases at Midway USA for $51.49 (on sale right now). For ~$1/case, why bother trying to make them out of something else?

That is what I did for 300 cases, have to trim a bit and works like a charm.

either works, it will be shorter than spec brass.

suggest selecting a length and trimming them all to that length AFTER a full power firing

hornady basic magnum brass may have to be trimmed

Why go through all the trouble? 416 Rem brass is readily available and pretty damn cheap for big-bore brass.

Thanx for all the replies! I guess I am still gun shy about not being able to get the brass that I wanted from a few years back.
I had trouble getting 8x57mm Mauser brass to make into 9.3x57 a while back and had to use .340 WM brass to make .375 AI due to only being able to find .375 H&H at about $2.00 a pop. I always like to have some options!

Thanks again!

Hip

I've run a 416 expander through 375 H&H and fireformed them. It seems to work, but like others have mentioned, the brass will shorten. You still have a neck to seat the bullet in but you won't be able to crimp and the neck tension may allow bullets to slip more easily.

The other aspect is when stretching the neck out to 416, the neck can stretch more on one side than the other causing an slightly off center bullet. If you can get 416 remington brass, buy it first, but 375 can be used in a pinch. Just don't expect good accuracy 375 h&h brass.

Thanx for the reply Gohip!

Hip

8mm Rem Mag brass works out better than 375H&H cases. I had to do that here in Oz 10 years ago when there was no 416 brass available....

Cheers,
Mark.

We do size brass both up and down to a number of cartridges, both factory and wildcats.

But, we use specially made dies that use different size buttons.

If done properly, we hardly ever loose a case.

quote:

Originally posted by gohip2000:

Just don't expect good accuracy 375 h&h brass.

I don't think you can say that as a general statement. It will depend on the brass, the rifle and also the loads.

However, I would always prefer to neck down so as to avoid the thickening of the bottom of the neck when necking up because part of the shoulder now becomes the bottom of the neck.

you are probably correct. I'm sure it can be done without thinning one side of the neck more than the other side. But all the brass I've resized, I could see a slight difference in thickness of one side of the neck vs the opposite side after stretching the neck diameter for the larger bullet. I was however using the expander plug on a regular set of 416 sizing dies, polished, and lubed. So this probably wasn't the ideal setup for expanding the neck.

Uniforming the case mouths as much as possible before necking up or down helps.
When I make 40-65 WCF brass from .45-70 Govt brass, I have no problems at all if I run them through a .45-70 FL die
for at least partial sizing/neck sizing before necking down.
If I don't do that I ruin a lot of brass.

If brass is not new, anneal,
anneal before necking up,
anneal after necking down.
Shoot it three times and anneal it again.

Squirrel season is coming ... GOR
Rip
.