475 bolt gun on a standard action

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26 March 2014, 06:08

Doug Turnbull

475 bolt gun on a standard action

Working on a new cartridge for the .474 bullets. Im shooting a 500 gr in a standard length action, cartridge OAL 3.400" at 2350 FPS. Pressures are under 50K. Will be 3 rounds down and 1 in the chamber when we are done with the extended floor plate.

26 March 2014, 06:26

RIP

Don't be coy, Doug, what is the basis cartridge you are wildcatting, or is it something unique, please do tell.

I am guessing shortened .416 Rigby like the .338 Lapua Magnum?
Like jeffeosso's 476 Rigby Accurate Reloading?

26 March 2014, 06:37

Doug Turnbull

Belted case .525 neck 2.7 OAL case .582 base

26 March 2014, 07:19

RIP

Ah so, shortened 460 Weatherby necked up to .475?

26 March 2014, 07:50

jeffeosso

some concept as the 476 rigby AccRel .. or the old 475 trollbane .. but with a belt...

2350 will be very low pressure ..

opinions vary band of bubbas and STC hunting Club

Information on Ammoguide about
the416AR, 458AR, 470AR, 500AR
What is an AR round? Case Drawings 416-458-470AR and 500AR.
476AR,
http://www.weaponsmith.com

26 March 2014, 07:54

Doug Turnbull

Yes. Shoots a 400 TSX at 2500 fps. Figure the belt will be a good way to control headspace with the mild shoulder. Low pressure so less chance at a stuck case. Feeds great and bolt closes on a case dropped into the action. More to come on it.

26 March 2014, 07:56

boom stick

A belt????? Say it ain't so Doug!!! That case needs a belt like Chris Christy needs another chin. I assume it has a shoulder right? The soon to be 476 Rigby AR is quite similar and may I say an ingenious name

. How aboot a new case that you can patent if desired say .580" belt diameter stepped to 550 case head tapered to .475 bullet without a shoulder? This could be necked to .510" for a sweet round as well.

577 BME 3"500 KILL ALL 358 GREMLIN 404-375

*we band of 45-70ers* (Founder)
Single Shot Shooters Society S.S.S.S. (Founder)

26 March 2014, 07:59

boom stick

Just read the new post that it has a shoulder. Variety is the spice of life as they say. I guess there will be a belted and non belted version. Let the fun begin.

577 BME 3"500 KILL ALL 358 GREMLIN 404-375

*we band of 45-70ers* (Founder)
Single Shot Shooters Society S.S.S.S. (Founder)

26 March 2014, 08:58

capoward

Interesting rational for the belt.
Sans belt and staying with the CIP/SAAMI shoulder diameter of the 338 Lapua Magnum with the .475 caliber bullet would give a slightly larger shoulder to bullet diameter relationship than the 12.7x68 Magnum (.500/.338 Lapua Magnum) and the .500 AccRel.
Belt isn't needed but to each there own...

26 March 2014, 10:24

RIP

quote:
Originally posted by capoward:
... Belt isn't needed but to each there own...

Ditto. Doug just wants to be different.

I do like that 2.700" case length in a 3.4" action.

No problem at all with .475-caliber bullets that are shorter than the usual .458-caliber bullets of same weight.
"Bore Law" makes the .475 the winner over the .458 for energy attained at lower pressure.
Loss of SD is made up for with modern bullet construction and velocity.