Lets say you have at your disposal an intermediate M98 that has a magbox limit of 3.150",....but you desired more 7mm power than an 7x57,...what of the following ideas (or your personal variations of) do you like?
Now folks, this is purely an mental exercise, that does not require cost or efficiency justification, its all individual choice, you know, just like some folks choose to spend more on engraving or extra fancy walnut.

7x57 AI
7x60s (necked down 8x60s)
7x60s AI
7MMx55 swiss (necked down 7.5x55 swiss ) staying away from rebated rim of 284win.
7mm/6.5RemMag.
7mm/ 300rcm
7mm/376steyr( with about .300 neck,.460"/25deg shoulder)
7x61 Sharpe&Hart... Drawing.,.... Next to 7x57 trim neck by .040 and essentially you have case length same as 376steyr, with .280" neck.
7mm/375Ruger Short(2.35 case length, about .300 neck and .490"/25 deg shoulder)
Ive kept the same approx. .042" body taper like in the 7x57 and 7x61 S&H, with none too radical shoulder angle, to try keep feeding good.

I didnt do anything on the RUM case, to avoid rebated rim.

8x57

easy one you forgot, .284 winchter...tj3006

Dear Trax:

Either a 284 Winchester or my favorite the 7x57 Ackley Improved of which I am building another on a 1908 Brazilian.

I have worked with a 284 Win. and the WSM family in a M48 Intermediate, and the feeding issues can be a bit of a nuisance. Getting the 7x57 AI to feed is a snap, and you don't have to adjust the magazine at all or change followers, just machine the feed rails.

If I were doing it, I'd use that intermediate length Mauser for a 257 Roberts or 6mm Remington, where your over all length is easily below 3.150". The 7x57 OAL stretchs out a bit for that confined magazine, but fits in a standard Mauser like a glove.

Sincerely,

Chris Bemis

Try the 7mm RSAUM. You can get virtually the same ballistics as the 7mm mag. If the rebated case bothers you, it appears that the 7mm/6.5 Rem. mag. is close.

That action makes a great .257 Roberts, it feeds like dream

Tom

Yale,
I generally work on .8" bullet projection from a case, e: 7x57 2.244+ .8"= 3.044" oal.
If theres room to seat out more than that, ie; another .1", (and my aim is to create a wildcat to increase power), then I would utilize that xtra mag space to accomodate a longer main body rather than long seating a bullet.... same goes for shortening the neck & shoulder to allow a longer main body.
So to reasonably increase or maximise 7mm power/capacity in an inter. 3.150'box, with still decent magazine capacity & reliable feeding, my mind tells something like this,
-an unrebated rim
7mm/376steyr(2.330"case, .460"30 deg shoulder, .284" neck)
7mm/375Ruger short(2.330"case, .490" 30deg shoulder,.284" neck)

truthfully, the basic 7x57 in 3.150 box has alot to offer without fuss and does most of what Ill ever need doing.. this extra power stuff is just a fun creative mental exercise at this stage.
I just noticed, 7mmRemington Magnum has only an .271" neck.

ackley..
or icl.
look for a 1-10 twist bbl have it ackleyed you'll like it.

I had mine done in .284 Winchester