Scopes were not even a part of the discussion in those days.

Outside of factory rifles, barrel (rifling) twist is not cartridge dependent. Krieger, Hart, Douglas, Lilja, etc. all offer .25 caliber barrels with twists as fast a 1-7". With a case capacity 20% greater than the 6.5 Creedmoor, one would think the 25-06 would far outclass the cartridge being discussed here. A possibly better one, although without quite as much potential as the 25-06 would be the .257 Ackley Improved. But we all find reason to justify the things we like (self included!).

The .25-06 would definitely have an advantage with the same bullet, but as you know the trade-off when you get overbore is barrel life. Recoil also becomes a consideration (for PRS shooters, and such).

I could be persuaded to use a 257 AI. Ballistically very similar to the 260 and 6.5 CM. I suppose I should find out how the 25 CM compares (which I might know if I’d read this whole thread).

These threads are enlightening to me. Always over my head, but the more I read the closer I get.

FYI, the .250 AI is remarkably similar to the CM (the .257 AI would give room for a bit more powder).

Advantage of the CM would be 1) easy availability of quality brass (though CM can be used as donor brass for the .250 AI), and 2) barrel twist rate more suitable for stabilizing heavy-for-caliber, high BC bullets, if interested in any long range shooting.

Well, the 250 AI and the CM, having the same basic case, should be very similar. The 257 AI should be a bit stouter, having more powder. Seems to me the 25 CM should appeal more to the target guys, but having CM tacked on to the name will have hunters wanting it too. Just the latest shiny object…

If they called it the 25 Buzzmore, would it sell as well?

The faster twist is good for heavier bullets for better penetration as well. The very fast twist of the 6.5x55 stabilizing the 156 grain bullets was its key to success as a moose getter. .257 caliber 134 grainers have an SD of .290, just a hair above .264 140 grainers at .287 which have good penetration in their own right even if they lag the .32 SD of the .264 156 grainers. .290 beats the SD of 180 grain .30 calibers and 160 grain .28 calibers too.

If success is measured by twist and penetration, get new barrel for your 257 or 250. Should be cheaper than a new rifle. But, I am in no way criticizing the 25 CM. Maybe it fills a gap, or maybe it creates a new gap and fills it. Either way it gets you to buy a new rifle, cause we sure weren’t gonna buy another 250, 257, or 25-06.

Now we wait for the 24 Creedmoor…

That would be 6mm Creedmoor. It was the first wildcat from the 6.5 Creedmoor, many years ago. It has been a SAAMI spec cartridge for quite a while.

If memory serves, the next wildcat was 22 Creedmoor. Which was Horizon Firearms necking down 6mm Creedmoor brass into .224

The 25 Creedmoor was the latest wildcat, and is also a SAAMI spec cartridge.

The Creedmoor has followed the same path as the .308 Win. A parent case with the necks changed to create new cartridges from it.

.243 Win
.260 Rem
7mm-08
.338 Fed

I think I will do a 17 Creed lol

My curiosity is a 7mm Creedmoor. How it stacks up against 7mm-08 A.I.

I know the case capacity of both. And I know the usual powder charge the A.I. receives, the Creedmoor should hold it. But that case geometry change, I don't know what it would do to external ballistics.

I'm not curious enough to have a custom reamer made, though.

Hornady has a pattern if you think back. GA Precision had the first run of the 6mm Creedmoor brass and sold it a while as Hornady watched to see if it would catch on. Then GAP did similar with the new 6GT with them guaranteeing Hornady a certain market for X amount of brass with exclusive rights for two years. Then Horizon did same with 22 Creedmoor so they committed to xx millions rounds before Hornady made the first cartridge. Now same is happening with 25 Creedmoor.

Can’t believe I forgot about the 6mm CM.

Mark at SAC has been building them for years. They won’t make the speed that a 708ai will.

Never loaded for a 6.5 cm but from reading it doesn’t even beat the 260, don’t see why a 7mm CM would beat the 7mm08 or the AI version.

It doesn't beat the .260, it shoots the same as a .260, doing it with a grain less powder.

Creedmoors are usually loaded with H-4350.

7mm-08 A.I. is often loaded with H-Varget. The amount of H-Varget that goes into a 7mm-08 A.I. with a 162 gr bullet, the Creedmoor brass will also hold it.

So if Remington had done a better job of supporting the .260, then Hornady might not have gotten their foot in the door like they did with the 6.5 Creed, and if that hadn't happened then maybe there'd have been no 6mm Creed or .22 Creed and maybe there'd be no thread on THF about the .25 Creedmoor. And I would not have typed this.

But then again, who's to say...

If grasshoppers carried .44s the birds wouldn't mess with 'em.

Remington could screw up a free lunch, when it came to supporting their cartridges.

6.5 RSAUM never took off either. Not compared to the 6.5 PRC.

Look at the brass side by side...

708ai has 58 grains of case capacity give or take depending on brass, Creed is 52.5 give or take. Not a ton of difference but enough that it simply won’t keep up. 6.5 rsaum was never a Remington offering. It was a pet project of George Gardner and he paid Hornady to make the brass. It worked well enough that Hornady decided to go all in, but they didn’t want anything to do with a Remington round. So they came up with the 6.5 prc. But ya, Remington is about as good at business as the dems are at running a government.

It might mean the Creedmoor would be more case fill, which is good. I've yet to see a 7mm-08 A.I. allow you to get to 100% cash fill with Varget. It's going to shoot tight and make velocity well before 100% case fill. After that, the brass is going to want you to stop adding powder.

I started doing some testing with H4350 on the 7-08 ai but found a Varget load I like so much I dropped the project. It does have better case fill with the 4350 and there may be something there but I’ll never know.

Two years ago, I got a call to develop a load for 7mm-08, for a hand loader. He had all the components, he just needed me to figure out the recipe. He asked me what I thought about H-4350 in the cartridge. My educated guess was the load would end up being a compressed load, but still not making the velocity that H-Varget would make. He said the main reason for using H-4350 was because he had a big supply of it. We moved forward with the project. My educated guess was correct. A safe, compressed load, but less velocity than H-Varget would have been making. It shot tight, it was just slower.

Granted, that was standard 7mm-08, and not Ackley Improved. I have not tested H-4350 in Ackley Improved, because if it ain't broke don't try and fix it. Meaning no need to stray away from H-Varget. So, I don't know what I don't know. If your 7mm-08 A.I. barrel is 24", H-4350 might be a good powder. 200 yard paper and a chronograph would tell the tale.

I do have a 24” barrel but will run out of A-Tips with about a thousand rounds left on the barrel. If I try a different bullet instead of buying more of them I may pursue the 4350. I have plenty of both powders. I wish the A-Tips didn’t shoot so dang good for me, they’re high siding bad in price.

I tested H-4350 in my standard 20” 7-08 years ago with a 162 ELD-M. My experience mirrors J.G.’s. A full compressed load at book max was a good 80 fps + slower than my Varget load. It shot good, but the speed wasn’t there. Just too slow a powder for that short barrel. You might see some appreciable gains in a 24” barrel, as I’ve heard guys getting good velocity with it in longer barrels.