This is a necked up 375 RUM with no other changes, but a 1 in 10 twist rate for 500 gr .416 cal bullets.

I think this is a GREAT idea, as it duplicates the 458 LOTT with a 500 gr bullet at 2350 fps, but will still shoot 300 gr spitzers over 3000 fps. Reduced loads duplicate the 416 Rigby and 416 Rem, all in a std Mag length action.

How would this differ from the 416 Dakota?

I will be shoting one across the chrongraph in a month or so, still waiting for the reamer.

My reamer is throated so 400 grain bullets will have the base of the bullet at the bottom of the neck. This gives a long COL, over 3.8 inches, so a big action is required. Gives more case capacity, as the bullet is not taking up valuable powder space. First rifle will be on the Olympic Ultra Mag Action. Could also use a CZ550, or a 602.

You could also build on a M70 or a M99 with the ultra box and follower, at the expense of a shorter COL and less velocity.

Chorongraph results could be interesting.

[ 10-18-2003, 00:33: Message edited by: John Ricks ]

cheaper brass.
John, is this a straight 415-375 RUM?
Looks like you could leave the shoulder-body junction, and give it a .4" neck and come out with about a 30 deg shoulder. Nice and easy.
I should think 500g @ 2350 would be pushing it pretty hard, though. Give it a 27" bbl and you might see it.

[ 10-18-2003, 00:45: Message edited by: Bwana-be ]

John -

Thanks for the reply. Would you share the chrono results as they come in? My experience with the 416 Remington, after chronographing over 1000 handloads, is that the extra capacity of the 416 RUM will put it dead center in the AA4350 burn rate with 400 gr bullets. Even the 416 Remington does 2450 fps with AA4350 at 44,000 CUP, compressed. With your case capacity, 2650 fps is not out of reach.

I very much like your use of the longer action not just for the extra capacity with 400 gr bullets, but also to make room for 500 grain Hawks.

What twist rate are you using?

Yep, it is just a necked up 375 Ultra, to simplify case forming matters.

12 inch twist barrel, a Pac Nor Stainless. Complete rifle will receive the black Robar Roguard with NP3 internals.

I will post chorongraph results.

The long action will enable ust of the 500 grain bullet, might give some interesting results.

If it reaches 2350 or so with a 500, can you say penetration? Nice sectional density!

quote:

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If it reaches 2350 or so with a 500, can you say penetration? Nice sectional density!

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John looks like you might have to find a dead whale on the beach out there to do you penatration test!

The Coast Guard has used this bullet in a 416 Rem to shoot "sharks" through over 4 feet of water.

John, 500 grains wow! a guy could clear the stumps outa the back yard ! Mount it in a 40 MM type gun tub to save the brass, and let the boys out at Neah Bay try it on the next Whale Hunt!
walex

Gents;

I just got off the telephone from talking with Midway.

They have an inventory-reduction sale running on .375 Ultra Mag brass, and the stuff costs just $9.99 per 20, instead of the catalog price of $16.58. I oredered twice as much as I'd originally planned....!

You UM wildcatters and .404 Jeffery shooters might want to get in on this.

Regards from BruceB (aka Bren Mk1)