Any of you learned members know anything about this cartridge listed in Frank Barnes book?

don't know of the 375/303 but there was a reasonable popular 35/303 many years ago they made good scrub guns by all accounts

That cartridge caught my attention, too. I borrowed once a copy of the book British Sporting Rifle Cartridges by Bill Fleming, and it had some information on it.

It said the originals went back to at least 1905 and used 42 gn of Axite, a form of cordite. (Modern shooters of NE rounds report a substitution of Reloder 15 at 1.19 times the weight of cordite is about correct.) The case could be formed today using .405 WCF brass, but the rims would have to be thinned, a chore. Bertram offers the parent .375-2.5" case, but the rims on that are also too thick. I estimate the case has a water capacity of between 62 and 63 gn. Woodleigh makes a 215 gn bullet of the correct size, but it is rated to only 2200 fps, which is far too slow for this round. Performance exceed that of the early .30-06 loads. Both QuickLOAD and the Powley Computer estimate pressures on the order of the .308.

You might be able to get more information via the forums at www.NitroExpress.com .

If you're looking for a rimmed .30-06 class cartridge, there are some wildcats that are less hassle. Better, the 7.62x53R Russian service round can use the same bullets and has the same case capacity; or you could build it with a standard .308 barrel as well.

Thanks asdf for the info-I was interested in building a rifle on a Nos4 Enfield action in a classic but powerful calibre.

How about the .375x2.5" NE? Brass and bullets are both available. CIP pressure rating is well below the .303's, so you could probably get more out of it than the original loadings. The Powley computer says 2100 fps with 300 gn should be feasible from 24", maybe 2200 with the 270 gn.

Another possibility is the 7 Fl H&H Mag. Bertram makes some pricey brass for it, and bullets are the standard .284's. As with the 375/303, if you wanted to form brass from .405, you'd have to thin the rims.

The .303 itself is plenty classic, and with modern ball powders, you might get 2300 with the 215 gn bullets.

The rimmed versions of the 7x57 and the 8x57 both are rated at lower pressures. Brass for both are available from all the better European makers.

quote:

Originally posted by wombat:
Thanks asdf for the info-I was interested in building a rifle on a Nos4 Enfield action in a
classic but powerful calibre.

this is probably not what you are looking for but have you thought of trying the 303 Epps? this is an improved version of the 303 that in a no4 almost makes 30/06 factory ballistics it would be a lot less mucking around and you can use your existing barrel check out this site http://www3.sympatico.ca/shooters/303Page.htm