"Modernizing" older cartridges?

[Bidwell]

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.

 

[Macintosh]

Theres a few cases of newer guns chambered with a faster barrel twist which facilitates heavier bullets (1:8 .223 and .243, etc), but I think the saami spec pretty much negates much of the tweaking that would be done on an existing cartridge in a factory gun. But plenty of people doing customs chambered and twisted for specific heavier than normal bullets. Doesnt a 308 already do well with a 175ish grain bullet?

 

[Bugger]

The 308 cartridge is great, but it’s size doesn’t have a whole lot more to give in 30 cal. It’s too slow with the heavies for a faster twist to be worthwhile, and there’s not enough shoulder to increase the angle and straighten the case to gain much velocity. Two ways you could go is 300wsm for a 30 cal with more velocity, especially if it’s a faster twist for the real heavies, or the generally accepted modern replacement is the 6.5 creedmoor for a more manageable high volume shooter.

 

[Bidwell]

Theres a few cases of newer guns chambered with a faster barrel twist which facilitates heavier bullets (1:8 .223 and .243, etc), but I think the saami spec pretty much negates much of the tweaking that would be done on an existing cartridge in a factory gun. But plenty of people doing customs chambered and twisted for specific heavier than normal bullets. Doesnt a 308 already do well with a 175ish grain bullet?

That's true. Yeah I've heard the 243 has some faster twist rates for longer range, heavier bullets.

308 does fine in that grain range. Although I don't shoot them much. I tend to go in the other direction since in live in CA and do a decent amount of reloading for light for caliber copper bullets.

 

[Koda_]

I dont know whats possible with a 308, but I modernized my old 25-06 with an Ackley Improved chamber, 7 twist barrel custom throated for the longer higher BC bullets.

If you can find someone who sells a longer than usual bullet in your caliber then work backwards from there to what you need to modify your old rifle to shoot them. Look up "modern cartridge design", thats what you need to do to upgrade an old caliber.

 

[Bluefish]

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.

You are basically looking for a Hornady formula 30 cal. It would be a 30 creedmore if there was one. You can update the 308 chamber and twist rate, but are still limited by mag length. Really need to shorten the case to get maximum performance. The push now is away from 30 cal to 6.5, 25, 6 or even 22, not much demand for a 308 speed 30 cal. The big 30 bullets are now over 200g to get better bc and you need case capacity to get enough velocity. Hence the 300 prc.

The Hornady formula is faster twist, shorter case, steeper shoulder and tighter chamber dimensions. 260 rem vs 6.5 cm, 243 vs 6 cm, 7 prc vs 7 rm, 300 prc vs 300wm.

 

[Bidwell]

I dont know whats possible with a 308, but I modernized my old 25-06 with an Ackley Improved chamber, 7 twist barrel custom throated for the longer higher BC bullets.

If you can find someone who sells a longer than usual bullet in your caliber then work backwards from there to what you need to modify your old rifle to shoot them. Look up "modern cartridge design", thats what you need to do to upgrade an old caliber.

Interesting! I've always wanted to try the 25-06. The first thing that popped in my mind was a Barnes LRX, they are definitely long. I've read there some hand tools for increasing the throat without using a lathe. Maybe I can turn my old ruger american into test rifle

I'll check out modern cartridge design, appreciate the tips!

 

[Bluefish]

Interesting! I've always wanted to try the 25-06. The first thing that popped in my mind was a Barnes LRX, they are definitely long. I've read there some hand tools for increasing the throat without using a lathe. Maybe I can turn my old ruger american into test rifle

I'll check out modern cartridge design, appreciate the tips!

You can do a fast twist 25-06 or a 25 prc. Basically a 6.5 prc necked down to run 25 cal. There are several new 130+ 25 cal bullets. Hornady also just released a 25 creedmore which is saami spec. A few hundred fps slower than the 25-06 or 25 prc.

 

[Bidwell]

The 308 cartridge is great, but it’s size doesn’t have a whole lot more to give in 30 cal. It’s too slow with the heavies for a faster twist to be worthwhile, and there’s not enough shoulder to increase the angle and straighten the case to gain much velocity. Two ways you could go is 300wsm for a 30 cal with more velocity, especially if it’s a faster twist for the real heavies, or the generally accepted modern replacement is the 6.5 creedmoor for a more manageable high volume shooter.

I may move up to the wsm at some point but it's hard to justify since I won't be shooting anything larger than a deer for the foreseeable future, and I wont be shooting past 400 yards. The 308 sort of fits this kinda funny gap with copper bullets. Within around 400 yards, it hits harder and has higher muzzle velocity than a 6.5. Don't have to worry about barrel life, easy to find components and the 308 is just on the edge of comfortable shooting with an ultralight rifle. But with a 6.5, you could probably on a average shoot smaller groups from any particular factory rifle. Something to be said for that. I guess that was sort of where my thought was going. Give me a 308 that has some subtle but significant design improvements that keep all the good stuff (barrel life, recoil, in my case muzzle velocity on light bullets, larger frontal area ) but impove overall precision. The .270 is interesting. Has just about the same muzzle velocity for a 130 ttsx as a 308 and a little larger than the 6.5

 

[Bugger]

I may move up to the wsm at some point but it's hard to justify since I won't be shooting anything larger than a deer for the foreseeable future, and I wont be shooting past 400 yards. The 308 sort of fits this kinda funny gap with copper bullets. Within around 400 yards, it hits harder and has higher muzzle velocity than a 6.5. Don't have to worry about barrel life, easy to find components and the 308 is just on the edge of comfortable shooting with an ultralight rifle. But with a 6.5, you could probably on a average shoot smaller groups from any particular factory rifle. Something to be said for that. I guess that was sort of where my thought was going. Give me a 308 that has some subtle but significant design improvements that keep all the good stuff (barrel life, recoil, in my case muzzle velocity on light bullets, larger frontal area ) but impove overall precision. The .270 is interesting. Has just about the same muzzle velocity for a 130 ttsx as a 308 and a little larger than the 6.5

The only thing wrong with the 308 is it’s been around long enough that rumors have turned into lore. I wouldn’t worry at all about the accuracy of one in any modern rifle compared to the other cartridges. Get whatever you can shoot the best and most, no deer will know the difference when hit.

 

[Bidwell]

You are basically looking for a Hornady formula 30 cal. It would be a 30 creedmore if there was one. You can update the 308 chamber and twist rate, but are still limited by mag length. Really need to shorten the case to get maximum performance. The push now is away from 30 cal to 6.5, 25, 6 or even 22, not much demand for a 308 speed 30 cal. The big 30 bullets are now over 200g to get better bc and you need case capacity to get enough velocity. Hence the 300 prc.

The Hornady formula is faster twist, shorter case, steeper shoulder and tighter chamber dimensions. 260 rem vs 6.5 cm, 243 vs 6 cm, 7 prc vs 7 rm, 300 prc vs 300wm.

30 creedmoor, I think that's pretty accurate!! The only thing I don't like about the current trend is barrel life. But I guess that's the cost of extra performance. And the modern advancements seem geared towards long range shooting. I don't think I'll ever get into that. I'll be a happy camper if I can comfortably hunt out to 400 yards.

I do like some of the howa mini actions, a 6mm arc could be fun. Orrr, what's up with the 338 arc?

 

[Bidwell]

The only thing wrong with the 308 is it’s been around long enough that rumors have turned into lore. I wouldn’t worry at all about the accuracy of one in any modern rifle compared to the other cartridges. Get whatever you can shoot the best and most, no deer will know the difference when hit.

True. I got a howa superlite in 308 pretty recently. Shoots great after playing around with a few loads and some stock adjustments. I just sort of got to thinking about about why legacy cartridges aren't refined more often. I may have satisfied my curiosity though. Seems like the Ackley Improved process is pretty much exactly what I was thinking, 308 AI. 40 degree shoulder and slightly lengthened case body. But from what I'm reading it's not worth the effort, even though they do sell tools for doing this and lots of info out there.

 

[Koda_]

Interesting! I've always wanted to try the 25-06. The first thing that popped in my mind was a Barnes LRX, they are definitely long. I've read there some hand tools for increasing the throat without using a lathe. Maybe I can turn my old ruger american into test rifle

I'll check out modern cartridge design, appreciate the tips!

You can do a fast twist 25-06 or a 25 prc. Basically a 6.5 prc necked down to run 25 cal. There are several new 130+ 25 cal bullets. Hornady also just released a 25 creedmore which is saami spec. A few hundred fps slower than the 25-06 or 25 prc.

The quarterbore is trending right now in new modern high BC bullets being made for it, there are several good bullets to choose from now. I'm fond of my ol 25-06 so I Ackley Improved it but there are some really good brand new modern equivalents now. Another advantage to the .25cal is the longer bullets give them a higher sectional density making them hit above their class traditionally.
For reference I'm sending a 127gn Hammer at 3050fps.

 

[Bidwell]

The quarterbore is trending right now in new modern high BC bullets being made for it, there are several good bullets to choose from now. I'm fond of my ol 25-06 so I Ackley Improved it but there are some really good brand new modern equivalents now. Another advantage to the .25cal is the longer bullets give them a higher sectional density making them hit above their class traditionally.
For reference I'm sending a 127gn Hammer at 3050fps.

View attachment 859360

That's a nice cartridge. Been wanting to try hammer bullets

 

[AZ_Hunter]

The quarterbore is trending right now in new modern high BC bullets being made for it, there are several good bullets to choose from now. I'm fond of my ol 25-06 so I Ackley Improved it but there are some really good brand new modern equivalents now. Another advantage to the .25cal is the longer bullets give them a higher sectional density making them hit above their class traditionally.
For reference I'm sending a 127gn Hammer at 3050fps.

View attachment 859360

That’s sweet. How long is your barrel? What powder are you using?

 

[Koda_]

That’s sweet. How long is your barrel? What powder are you using?

26in 7 twist barrel, H1000 powder.

 

[112Savage]

The “Hornady Sauce”/modern design 308Win would be the 30 T/C which is the parent case for the 6.5 creedmoor. The secret sauce isn’t necessarily the tight twist or heavy bullets; it’s the leade angle/throat diameter/throat length.

Sammi 308 is very sloppy in the throat. It needs to be. It was designed for use in machine guns. 30-06 is much the same. Some rifle builders have improved upon this with custom reamers (I.e 30-06 Serengeti reamer) but getting around sammi in a factory gun would cause problems.

So if you’re looking for a “modern 308” you missed the bus with the 30T/C or you need to go custom

 

[Mike D Texas]

I “modernized” a 264 Win Mag. I had a buddy give me a few hundred pieces of brass and a set of dies a while back. I love a good 6.5mm cartridge so I said why not. Also had a Proof barrel laying around.

Ackley Improved case, throated for 156 Bergers.

3250fps with room for more.

Can’t help on the .308 though.

 

[Slickhill]

If you’re a handloader you can control headspace and therefore brass fit or “slop” by adjusting your sizing die.

Case design has so little to do with accuracy that Joe Average shooter isn’t going to be able to tell a difference with properly put together ammunition for the rifles in question. I have seen very accurate target rifles built back in the 60s that were chambered for cartridges with what is now considered horribly inaccurate case designs, 225 Winchester, 22 Hornet, even one in 30/30.

Make sure your rifle is squared away re bedding, mounting setup, good optic and trigger. Fit brass to same via proper sizing. Match seating to the throat as best as possible with a quality bullet and get to shooting. 99 percent of people have more room to improve their shooting than they have room to improve on inherent accuracy potential by fiddling with cartridge design.

 

[TaperPin]

I just sort of got to thinking about why legacy cartridges aren't refined more often.

Cartridge design is really interesting, and learning about the history of how designs have evolved gives a person a new appreciation for the good and bad aspects of new designs. The idea of updating cartridges isn’t new, but the idea that updates have to be offered in factory rifles and have readily available ammo is. Just a few decades ago many more serious shooters were reloaders and a cartridge to duplicate the performance of something like the 6.5 creedmoor is as simple as ordering a 260 Ackley Improved fast twist barrel and getting a set of dies. The 22-250AI in a fast twist barrel does everything a 22 creed can and has for quite a long time.

Barrel manufacturers that also install barrels often have multiple options for popular cartridges and throats can be set for any bullet you want. There are a lot of benefits to fine tuning a custom reamer to meet your needs and have a barrel chambered with your reamer rather than whatever a gunsmith has - it’s very close to having a pizza made with the topping combinations you want vs the meat lovers, or six other combinations listed on the menu.

Not everything about straightening out body taper and increasing shoulder angle is an actual improvement. Every month someone posts a problem rifle that has clickers with normal pressures - a common problem when body taper is minimized. The 300 PRC is so problematic the Alex Wheeler reamer to add more taper to the chamber walls is a defacto standard with many gunsmiths. The fat shoulders don’t always feed great in factory double stack internal magazines and it makes tweaks to the magazine spring more common. Traditional designs feed great and rarely cause clickers unless the pressures are too high.

The more someone learns about past and present cartridges, the more obvious it becomes that marketing drives the popularity of many modern designs, and they aren’t really better than past options, but simply more convenient. Marketing money is also responsible in part for the downfall of reloading - ammo sales are much more profitable than components.

I was well into my 30s before realizing the majority of reviews, ads, and testimonials that drove my purchasing decisions were backed with marketing $$$$ and many competing brands were as good or better. It’s big business.