Pondering a wildcat.

[Grumpy_old_Fart]

I typed for 10 minutes.. and it didn't edit my post, darn it.. this may take a bit.

 

[Grumpy_old_Fart]

1. Having a belted rim doesn't make cartridge better. Proven fact.

2. Short fat powder columns burn more efficiently.

C. Twist rate improvement to 1:8 is necessary for longer bullets.

D. Like someone in the world of Pro-Stock drag racing said, " don't use any more than what it takes". (Specifically, "don't use a longer connecting rod than you need")

So, in this case, the goal is a .277 bullet, weighing up to 180 grains, seated long to avoid Delta V issues, traveling at 3000fps.

You don't need a cavernous 27 nosler case to do it. You can do it with 1/4" shorter case filled to 93% capacity.

Only use what it takes. Get there by design, not by mistake.

A .277 170gr Berger has a sectional density of .317, the 7mm 175 has a sectional density of .310, the 180gr has a sectional density of 319.
With a 277 bullet, you can surpass the point of diminishing returns.

 

[Archie]

Agreed. I'm wanting to get away from the long skinny powder column and 1:10 twist. Maybe I'll just do this myself without input.

You may be on to something in that thinking.
I've studied the history of smokeless cartridges for a number of years. I think most everything needed has been tried, at least once. Still, new ideas can be better than 'entrenched' thinking. The late Dr. Einstein is a good example.
But not everyone is a Dr. Einstein.
The other caution is getting such a concept put into metal. If one can't do all the fabrication themself, one depends on someone else. Someone else who will build things as the designer wants and not what the builder 'thinks' is best. Take lots of money.

 

[Nature Boy]

Sounds like a 270 WSM

 

[AJC1]

So is the cost of a new barrel less than clambering a special one. Is it the adventure or the result. I can't immagine the machine time, special reamer, or dedicated dies would provide any savings.

 

[Grumpy_old_Fart]

So is the cost of a new barrel less than clambering a special one. Is it the adventure or the result. I can't immagine the machine time, special reamer, or dedicated dies would provide any savings.

Of course there is never a savings. A new barrel is around 600-900 depending on options. The reamer is 200-300.

This is typical, though.

 

[WestKentucky]

My immediate thought was exactly as the first couple replies. 6.8 western and 277 fury. Don’t forget the 277 weatherby either. The weatherby always seemed like a good idea that was poorly executed in my mind. Kick it down to short action cartridge length but load it with heavy for caliber boattail ballistic tips and your in the same ballpark as what OP is describing. Heavy as in long and loaded long where it wouldn’t fit in a short action rifle. I sometimes have trouble finding the words to describe what’s in my head.

 

[Grumpy_old_Fart]

My immediate thought was exactly as the first couple replies. 6.8 western and 277 fury. Don’t forget the 277 weatherby either. The weatherby always seemed like a good idea that was poorly executed in my mind. Kick it down to short action cartridge length but load it with heavy for caliber boattail ballistic tips and your in the same ballpark as what OP is describing. Heavy as in long and loaded long where it wouldn’t fit in a short action rifle. I sometimes have trouble finding the words to describe what’s in my head.

Make it in-between short and long action lengths. Cartridge length at 2.375. usable in a long action even with a tight magazine.

 

[BigBlue 94]

Neck down a 375 Ruger to 277... Slightly smaller diameter case than 270 WSM, but .480" longer. The standard 375 Ruger has a case capacity of 99gr of water. The long case gives you plenty of material for a shoulder.

 

[Armorer 101]

Seems to me, I read Rick Jamison’s original articles, he did a 270 as part of his original research on the shortened 416 cases. But as usual, for publication, most of his loads were with mid weight. No reason with the right twist, you could not throw a .277 at 170 or so at or near 3,000 fps with an 80g-85g capacity case in the #1.
The point of mentioning the 270 Wetherby is it can be done with roughly the same case capacity. The belt has nothing at all to do with it, as you noted.