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Recently, Two(2) interesting things have happened:

1. SAAMI (Sporting Arms and Ammunition Manufacturers’ Institute) approved this new cartridge:


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2. This Trade Mark was filed:




Appears that Winchester/Olin - is on the verge of correcting the shortcomings of their .270 WSM.




GR

I noticed they have spec'd it to the 10 thousandth of an inch--just like the Creedmoor

But, why?

Looking at load data, I don't see any benefits, what am I missing?

It's twisting at an 8. For long, heavy bullets, instead of the 130-150gr bullets of the 1:10 twisted WSM and WIN.

Exactly.

... and the shoulder pushed back a bit... for...






GR

Dang. I don’t hate the 270 wsm.

They would make more money by just starting to sell 270 Winchesters with 8" twist barrels.

How many of these rifles will the have to sell to break even?

The next interesting round will be the 7mm PRC.

Top right corner says 175 gr at 2,840 fps out of 24" barrel

Lookin' into that very prospect.

- 24" R5 1:8 twist stainless .270 Win. re-Bbl. for a M700.
(and some Unicorn RL-26 powder)




GR

They also could’ve twisted the WSM properly from the get-go, but there seems to be a lot of old idea boys working in the big companies. They really have to have their noses rubbed in it before they catch on. ‘Twas ever thus.

Around 2003 when the 270 WSM came out I don't think fast twists were even a thing at that point. I know I have a 1-8 barrel for my 270 WSM that's been sitting for awhile since I am stuck on the 150 Partitions, Accubonds and Bitterroots.... It'll get done eventually though.

Thinkin' the 165 gr. ABLR... backed up by a 170 gr. Partition - SD=317 / BC(G1)~.520 / MV ~2900 fps/24" Bbl.

Woof.




GR

Oh they were, just not in most factory rifles (or .270s)

The 7mm Creedmoor will be my next build. The 7-08 is a great cartridge, but combine that with the case design and logistics of the Creedmoor, and I think it'll be a sweet little package.

My only criticism of the cartridge drawing is the .011" (plus .002") over nominal bullet diameter freebore. The tolerance should have been more in line with the CM's tighter tolerance. It seems like the tighter the tolerance on the reamer spec, the greater the likelihood that most rifles will shoot very well.

The case capacity appears lower on the 6.8 looking at case drawings. So twist the WSM faster and still be able to use factory shelf ammo, then you can still run the heavy reloads . This sounds better than waiting on other companies to jump on board.

How many companies would be willing to jump in when the same outcome could be accomplished with a simple rebarrel?

I am all for more choices, not less, but realistically how great a chance is there for this to succeed?

I included the 6.5 PRC drawing for reference since they are extremely close in dimensions.

It's not just the twist. It's a whole bunch of stuff. The reamer geometry and case shape and length (and width) of the throat on SAAMI spec reamers, along with COL. The WSM was not designed to shoot ultra-long projectiles with high BC and high SD. Sure, you can cram them into the case, but the SAAMI reamers used for factory rifles and standard magazine length were designed to maximize performance for bullets 130-150gr.

This new cartridge uses a very similar case, but seeks to correct the flaws in the platform. It has a faster twist, longer (and narrower) free-bore, shallower leade angle (for high BC bullets), and most importantly, the max COL is 2.955", so standard magazines will allow for long bullets to be seated long, into a target-leade-taper.

Not to mention nomenclature dysfunction RE: ammo. (See 7mm Rem Express)

As for case capacity reduction?

See that as a plus.

More efficient/less intrusion given applicable long bullets.

Maybe 3 grn less(water)...?

Call it 63 grn/.270 WCF < 69 grn/6.8 W < 72 grn/.270 WSM... for a 150 gr. bullet.

So, one 3 grn jump over a .270 AI.

For 150-175 gr. loads... for me...?

Ideal.

Already budgeting for a M70 EW/SS (24" Bbl.) in 6.8 WESTERN.

8>)




GR

This doesn't quite have the capacity of the 270WSM (lacks about 10gr). It's got about 2 more than the 270 win so with a better (read efficient) case design we'll just have to see how it performs.

I've decided I'm just going to buy an 8-twist 270 Win barrel that is throated appropriately, and swap it out on current 270. Maybe next spring.