I did a search on this and couldn't find anything.
375 Holland & Holland brass is relatively inexpensive and easy to find.Does anyone here form 416 rem mag from it.I know that it would need to be fire formed afterwards but I'm cheifly concerned about shoulder collapse during the neck expansion.
Will from 375 to 416 be too big a jump in one step?Would I need to do this in two steps?Any help would be appreciated.Thanks in advance.

Ray;

It's perfectly possible to fireform your .375 brass just as it is, which eliminates concerns about shoulder collapse, etc.

I would drop about 20 grains of 2400 powder into primed cases, fill them with cornmeal to the shoulder, and add a bit of tissue in the neck to hold it all together. Fire these rounds straight up in the air. This will probably form the case well enough to allow normal loading as a .416 Remington, although the shoulder may not have its "corner" completely filled-out. DO NOT USE A BULLET OF ANY TYPE, or even a wax plug in the neck.

Firing straight up gives better results, as I found that necks tended to form with some length irregularities if fired horizontal.

This has worked well for me in a number of cartridges.

Because both the .375 H&H brass and the .416 Rem Mag brass headspace on the belt, rather than the shoulder, I would think you could just shoot standard loaded .375 H&H ammo in your rifle to get fire-formed brass, and go from there.

I do that in forming the .404 Barnes Supreme cases for one of my rifles, and it works just fine. The .404 Barnes Supreme is virtually identical to the .416 Remington Mag, except it uses .411" bullets instead of .416" bullets....and is about 30 years senior to the Remington round.

Of course, it will not be accurate shooting during fire-forming, with the .375 bullet "rattling" down that bigger bore. And, when you go to use the brass for reloads, you should trim your cases to a uniform length, and be careful to NOT set the shoulder of the case back with the sizing die. (That way you will have the advantage, if there really is one, of headspacing on the shoulder, with the belt as a backup headspace "fail-safe".)

I had a Rem 700 in 416 Remington not long after the calibre was introduced and I had 40 factory rounds and used the 375 brass for the rest.

It necks up without problem and with the 400 grain Hornady seated it sort of looks like a 458 Lott with extra taper.

I was using the powder Americans call Varget but that was before Hodgdon started selling it so maybe a burn rate was a bit different but I could fit with compressed loads the the charge I was using in the necked up 375s. Point of impact was a little different but not by very much. However the Rem 700 had a very heavy barrel similar in contour to what is on a 460 Wby or Remington Varmint rifle.

Mike

Another option might be to use Hornady 375 Basic brass. It is full length straight walled brass. Just run it into your FL 416 Rem die. You might have to trim the length after sizing. This brass is a little more expensive than 375 H&H, but you don't have to take time time or the expense (bullets, powder, and primers) to fire form.

Sheesh...I just looked at a Midway flyer, and .416s cost $40/100 and .375s are $35....why are we bothering?

Hey RAY
check ebay I just paid $14.00 for 50 pieces of brass.

quote:

Originally posted by Bren Mk1:
Sheesh...I just looked at a Midway flyer, and .416s cost $40/100 and .375s are $35....why are we bothering?

That will NEVER work... Too practical, too sensible, too easy (Big Grin)!!!

I guess I'm a bit out of touch.My last contact with suppliers left me with a bleak outlook on 416 rem mag case availability.But that's been a while.Apparently,things have changed for the better.
Many thanks to all who responded.Lots of valuable tips were given here.Best regards.

raym