So, guys, here's a real question:
What action are people going to be chambering these "AR" rounds in?
The "fits in a standard action" thing seems to be a big part of the design intent, but if you're using an M70 you've got room for a full-length RUM case, and IT would have all this one has but more. Not to try to rain on it, but it seems like the 3.34" thing is for Remmies and Mausers. Maybe a pre-'64 standard.
I've been playing with the idea of 3.1" rounds for quite a while. They fit into Mausers with no real work, M70 shorts, the new MRC, even Yugo's.

I drew up a Rigby-based .475" (called 470 Mini-Maus) that was about 2.4" long with a .45" neck, .570" at the top of the body. It should hold about 96.5g of water under a 1.2" bullet with 3.1" COL, compared to the Capstick's 91g at 3.6" COL.
Some will say the M70/k98 can't handle the Rigby casehead. That discussion is already well-run on both sides so I won't address it.

Imagine a mini-Capstick with a bit less pressure, on a little M70 w/22" qrtr-rib bbl and a thick, miniature English Bigbore-style stock...
tres chic.
[And of course, the case design compares similarly to all the full-length blown-out H&H's in all calibers. ]

BB,
You are right.. there are better rounds for SOME actions... and better cases for more money.. and there will be higher pressure for more power (regardless of measurement)

However, let's look at the design constraints.

• brass
  rum brass 40 cents
  rigby brass $1.93 ~4.5 times the cost
  404 brass $1.55 .. ~4x
  460 weatherby $1.77 4+ x
  500 jeffe $4.20 .. ~10x the cost
  375 "basic" 50 cents .25X
  
• case head
  rum .530ish.. same as "every" magnum .. every maker has this bolt face, every smith can work with it
  
  460/rigby/500 jeffe - specialty case, all bolts (except weatherby, cz, and big ruger) have to be cut which means $$$
  
• mag length
  3.35 is do able in a mauser 98, mod 70, ruger 77, rem 700, savage 1x0, sauer, etc etc etc
  
  anything longer, unless you buy the low % sold longer boxes, requires $$ to change .. so, a ruger 77 in 300 win would require lot$$ of changes$$
  
  
• mag width
  this is the killer for larger brass. the wider the brass, the wider the required box, the more modifications required for proper feeding, and therefore more$$$$ I too have done several designs on rigby and 460 weatherby... and these are too wide for a proper staggered mag. the 550 express is a singlestack. which is $$$ for a smith to do
  
• action availability...
  for a rigby, 460, or 500 jeffe based round to stagger load in the mag, you must have a wide action, or an amazingly good smith ($$$) so that is ruger rsm, cz550, brno602, or enfield of the "common" actions
  
  for a 3.65" round (not wide) you have a wider choice.. some 700s, some 70s, some savages, som CZs, and then $$$$$ to modify a mauser or others.
  
  However, for basically a "standard" mag width, and a "standard" OAL, you have the choice of EVERY action that was chambered in 300 winmig.
  

So, in terms of precentages (remember, i firmly state that this is a compromise to be ~90%) you have something like 90+% of all actions made in 7 rem mag should be able to be modified by just about any shadetree gunsmith (again 90%).. run at 90% of the pressure of the capstick or lott, and deliver 90+% of the power...

Or, basically, a well thought out (that may not be the most humble thing I have ever said) round that will allow a fella to get into a serious DR for less $$ than just about anything else, and not have to bump his head on brass price, mag length, mag width, or limited actions.

on the rigby in a mauser.. it's a question of it feeding properly (sure, rigby did it.. can anyone afford to have rigby's paramount grandmaster class gunsmiths make them a rifle today?) .. from WIDTH and length..

So, the problems and hurdles I have tried to design around are, brass price, action availability, action price, and feeding.

Perhaps the taper won't be the easiest for feeding.. I think a 7rem mag, with the rails touched 1/2 up the case and a little feedramp, should feed like a hungry coon hound.


To answer your question, I will be building
470 on a ruger 77 mk1
458 on a mauser 98

and someone is asking me to build one on a remington 700!!

quote:

Imagine a mini-Capstick with a bit less pressure, on a little M70 w/22" qrtr-rib bbl and a thick, miniature English Bigbore-style stock...
tres chic.

that's exacly what we are designing for, for everyone who can afford a rebarrel.


You do know that all pre-64 wins are the same length, from 22h to 375hh length rounds? The difference is how much metal is cut out. so, except for some new "long" actions, you are facing a higher gunsmithing bill for a 3.65" round

jeffe

Bwana-be,

As a lefty, the M70 is my only real CRF option (and I see no point in building a big bore on a push-feed action).

I see your point about the .375H&H-length M70s being better suited for longer cartridges, but unless I can locate a LH M70 Featherweight ('available' in the WSM cartridges only at this time), I'm sticking with the long action.

George