Cartridges with the same/similar OAL as the .280 British?

[Robusto]

Cartridges with the same/similar OAL as 280 British for AR12.5?

Hi everyone. I was wondering what cartridges have the same (or basically similar) OAL as the 280 British. I am particularly interested in cartridges with an OAL between 2.45 and 2.60 that have an "auto-rim". I am thinking up a project utilizing an auto-loading rifle cartridge and the 280 looked like a good starting point, but I would love some options. The reason is that I'm collaborating with an engineer and a machinist to make an AR that is bigger than an AR15, but smaller than an ar10 and thus need something longer than the .223 family but shorter than the .308 family.
thanks

 

[rcmodel]

.280 British
Rim = .473".
Case = 1.71".
OAL = 2.54".

About any cartridge based on the .308 Win case fits the head size bill.
And any cartridge based on the .308 case "could" be loaded to the length.

A .250 Savage comes awful close.
As does a 7mm-08 Remington.

I would say though that it would be far less trouble in the end to make a new gun design fit an existing common cartridge length, then the other way around using an uncommon cartridge length.

rc

 

[Robusto]

thanks

RC-

I would say though that it would be far less trouble in the end to make a new gun design fit an existing common cartridge length, then the other way around using an uncommon cartridge length.

That's basically what I am trying to do... I was looking for a modern cartridge to fit in an auto loading rifle that was longer than the .223/ 5.56 family but shorter than the .308 family. it just happened that the .280 British seemed like it was about the size that I was looking for. I wasn't specifically wanting to use it.

Any thoughts?

thanks

 

[Robusto]

btt

 

[armarsh]

6.5 Creedmore (about 49mm case length),
6.5 x 47 Lapua

 

[68wj]

Makes me think of the 7x46 UIAC (7mm Murray) project.

http://www.thefirearmblog.com/blog/2010/04/07/7x46mm-uiac-universal-intermediate-assault-cartridge/