"Modernizing" older cartridges?

[Quandary]

Super cool rifles. The 25-06ai is the one that I’d like to build some day. There really is no getting around the fact that the 06 case is the Chevy small block v8 of rifle cases. Necked it down, maybe ackley it, and it’s going to crush most modern cartridges in velocity. Downsides are lack of head height to seat long bullets optimally, doesn’t do as well in short barrels and a long action if a guy cares about that.

Yes to make it work with the new class of 25s you need to go custom to punch out the free bore. You are also correct that it is not a case that is short barrel friendly. Mine is a 24" CRB and 24" is as short as I would go to make sure all the powder gets burned.

 

[Koda_]

What is your COAL with that load?

3.450" COAL.
The longer bullets require a custom throat length in the barrel.

 

[TaperPin]

Thanks. The project came out of a flier purchase on RS. Bought a LH Sako AV thinking if nothing else I could use the action for something. Well the barrel and stock are s**t but the action is in good shape other than cleaning off a bad Parkerizing job that was done on it.

So now what to do with this long magnum action. Didn't want to do another 25 as I can't beat what I already put together. Was thinking 244H&H, which would be a real screamer, but the more I investigated the harder (and unrealistic) that seemed to do. Than decided to go 300 H&H figuring that would be perfect for an Africa trip coming up in '27. Saw that Bartlein, which is 10 miles down the road, had a 308 #3b in stock. Took the action in and sat down with Frank, who it turns out is also is doing a Sako AV 300 H&H project. Frank has an "updated" accurized 300 H&H reamer in the works! Serendipity!! Bartlein will chamber the barrel when they get the reamer in and I'll get everything else and put it together in May I'm figuring.

That came together well! That’s awesome to be so close to Bartlein.

I also looked into the 244, but the only way I could see it working was doing it with a .243” bore instead of .245”, which as you know gets expensive paying for chamber and die reamers.

 

[AZ_Hunter]

3.450" COAL.
The longer bullets require a custom throat length in the barrel.

That would work in the UM tikka mags then.

 

[Koda_]

That would work in the UM tikka mags then.

Mine is a Remington 700 and it has plenty of room in the magazine but I would make a dummy round to double check. Whichever long heavy bullet you chose you want the most case volume to take advantage of the best velocity.

 

[PanhandlePilgrim]

I've read a little about how more modern cartridges are designed with tighter tolerances and other "accurizing" attributes than say something like 308 win or 30-06.

I know the 308 maybe isn't the best at anything in particular but I like the versatility, barrel life and its pretty darn accurate as-is. But that said, it was designed in the 50's and there doesn't seem to be anything out there that's basically the 308 but with some of the modern cartridge advancements, sort of like a 308 v2.0. Would there be a market for something like that, and what would you do to squeeze out a little more "inherent" accuracy from it? It seems like new cartridges come out at a pretty decent rate, relatively, but there's never refinement on past versions. Which is sort of unlike any other product.

I know that if you create a custom rifle you can decrease tolerances and increase accuracy/precision. As a reloader I'd be curious to learn more about how'd you'd go about working with a gunsmith to create a rifle for a specific projectile and brass cartridge as well.

Look up the 30 TC, it is the round that the 6.5 creed was developed from.

 

[RME]

I’m actually getting ready to do just that only you don’t need custom dies at all. For chambering my barrel I will be using a 30 tc reamer, and a 277 fury go gauge. I will be using a 30 tc resizing die since the stainless part is smaller in diameter and doesn’t touch the die anyway. I have a Tikka t3x action which can be changed back and forth between long and short depending on what bullets I’m using at the time. I will be running a 1 in 8 so that I can use the 212 bore rider, and there is no such thing as over stabilizing. The only thing you get with more spin is more spin drift. Modern bullets at 3k or less are not going to vaporize. 4k plus maybe. I won’t be going that fast anyway. I don’t know what powder I’m going to start with, but I am leaning towards Accurate 2520 for my heavies.

I use AA2520 in my 30 TC with 178 Eld-X's and it shoots well. I'd probably also try Varget if the prices hadn't gone up so much.