.308 Improved - to be or not to be...

[Nature Boy]

My question is, if there’s no good reason to Ackley-ize the .308, what’s the reason for doing it to other .308 based cases like the .260, .243 or 7mm-08?

I think that doing it for the simple fact that it’s a little different has some merit in it’s own right. If it reduces the amount of trimming that’s a bonus.

However, if you’re shooting it in F Open then I would have to agree with others that it sounds like a step backwards

 

[Zero333]

My question is, if there’s no good reason to Ackley-ize the .308, what’s the reason for doing it to other .308 based cases like the .260, .243 or 7mm-08?

I think that doing it for the simple fact that it’s a little different has some merit in it’s own right. If it reduces the amount of trimming that’s a bonus.

However, if you’re shooting it in F Open then I would have to agree with others that it sounds like a step backwards

The 243win, 260rem & 7-08rem have longer shoulders. Specifically the 243win and 260rem have much longer shoulders than the 308win. Thus they gain more capacity with a 40 degree shoulder than the 308win.

 

[XTR]

My question is, if there’s no good reason to Ackley-ize the .308, what’s the reason for doing it to other .308 based cases like the .260, .243 or 7mm-08?

I’ve given my opinion on more than one occasion that it is not worth it*. When I looked into a 7-08 hunting rifle I thought about doing an AI, the gain of ~4% in capacity and maybe 100fps wasn’t worth it to me. My 25” barrel runs 140s @ 2900 w/o pressure, why bother.

when I built a 6 I decided on the SLR instead of the AI. Longer neck, better shoulder, no fire forming, and my once fired cases still the same H2O capacity as a new 243.

The conventional wisdom is that a 30-06 gets about 150fps more than a 308 with ~21% more capacity, so what can you really expect if you AI any 308 based case?

If you want the easy button for a longer neck and a 35* shoulder do an SLR, if you want more velocity get a bigger case.


* just that an opinion, there are lots of them on the www...

on the other hand, if you just want something different don’t pay a bit of attention to anything I’ve written above and do what ever you want. It’s your gun.

 

[miningshawn]

Alright, lots of good dope here. I really appreciate all of the replies and.....

I'm going with something all new. I have 5 .308's, 3 30-06's, and 2 300WM's. I want something a little different. I have (I counted!) 12,632 once fired Federal GMM cases - I didn't even bother counting all of the once-fired LC cases I have, something like 2/3 of a 55 gallon drum. I'm working to get the most volume in a .308 case by putting the shoulders forward, taking out the tiny bit of taper, and reducing the neck length.

Why?

Because I can. The rifle needs a new barrel and I am curious just how far I can push the .308 case. Reamer coming from PT&G, barrel from McGowen, and I am still looking for a someone to do the sizing die. I will be setting this up around the Berger 185 Juggernaut and AI magazine length. If it works in a 700, I might even try it in an AR10.

This should take a few months to get everything together, and I am looking forward to the results. Thanks again for your input!

 

[Nature Boy]

Can’t wait to see it come together

 

[1shot]

I’ve given my opinion on more than one occasion that it is not worth it*. When I looked into a 7-08 hunting rifle I thought about doing an AI, the gain of ~4% in capacity and maybe 100fps wasn’t worth it to me. My 25” barrel runs 140s @ 2900 w/o pressure, why bother.

when I built a 6 I decided on the SLR instead of the AI. Longer neck, better shoulder, no fire forming, and my once fired cases still the same H2O capacity as a new 243.

The conventional wisdom is that a 30-06 gets about 150fps more than a 308 with ~21% more capacity, so what can you really expect if you AI any 308 based case?

If you want the easy button for a longer neck and a 35* shoulder do an SLR, if you want more velocity get a bigger case.


* just that an opinion, there are lots of them on the www...

on the other hand, if you just want something different don’t pay a bit of attention to anything I’ve written above and do what ever you want. It’s your gun.

Just for the sake of statistical accuracy, the SLR has a 30* shoulder, not 35*. It's basically a 6BR top on a 243 bottom. Because you are moving the shoulder back and changing the angle, you do indeed fireform the brass although some of the forming is done with the sizing die.

Lloyd

 

[Ned Ludd]

Something else to consider regarding the potential benefit of improving the .308 Win case is not just the theoretical gain in velocity that can be made from the relatively small increase in case capacity, but also whether or not that increase is actually sufficient to be realized in terms of a tuned load. If the modest increase in performance isn't sufficient to allow you to hit the next higher node with a given powder, bullet weight, and barrel length, you could end up tuning to the same node you could already hit safely with a standard .308 Win case.

You seem to be fairly set on using the 185 Juggernaut for this experiment, so I would suggest thinking very carefully about powder selection and barrel length in order to maximize any gains you might realize from the increase in case capacity. If you have a copy, QuickLoad reloading software is an excellent tool to analyze just these types of parameters in silico.

 

[miningshawn]

Something else to consider regarding the potential benefit of improving the .308 Win case is not just the theoretical gain in velocity that can be made from the relatively small increase in case capacity, but also whether or not that increase is actually sufficient to be realized in terms of a tuned load. If the modest increase in performance isn't sufficient to allow you to hit the next higher node with a given powder, bullet weight, and barrel length, you could end up tuning to the same node you could already hit safely with a standard .308 Win case.

You seem to be fairly set on using the 185 Juggernaut for this experiment, so I would suggest thinking very carefully about powder selection and barrel length in order to maximize any gains you might realize from the increase in case capacity. If you have a copy, QuickLoad reloading software is an excellent tool to analyze just these types of parameters in silico.

All very valid and very good points.
For powders I am looking at Varget, CFE-223, 4350, AL-16, AL-17, VVN150 and VVN540.
Primers will be CCI-BR2 and CCI #250.
I haven't used Quickload. I don't even use a cronograph until the load is developed enough to be consistently good.
Barrel will be 28" SS, Medium or Heavy Target, 1:10.

The reason for the Juggernaut? I really like the versatility of it. VLD,s are great; but, tend to give me fits when I cannot touch the lands. I hate single feeding - I mean I really really hate it. The Jugg's ogive is so much more forgiving with a magazine. Even though this is a niche project I am looking for a little versatility. The Juggs IMO also tend to fall close to my absolutely favorite hunting bullet - the Berger 185 Classic. I can usually start very close to the load developed for the Jugg and switch to the Classic.

 

[Homerange]

All very valid and very good points.
For powders I am looking at Varget, CFE-223, 4350, AL-16, AL-17, VVN150 and VVN540.
Primers will be CCI-BR2 and CCI #250.
I haven't used Quickload. I don't even use a cronograph until the load is developed enough to be consistently good.
Barrel will be 28" SS, Medium or Heavy Target, 1:10.

The reason for the Juggernaut? I really like the versatility of it. VLD,s are great; but, tend to give me fits when I cannot touch the lands. I hate single feeding - I mean I really really hate it. The Jugg's ogive is so much more forgiving with a magazine. Even though this is a niche project I am looking for a little versatility. The Juggs IMO also tend to fall close to my absolutely favorite hunting bullet - the Berger 185 Classic. I can usually start very close to the load developed for the Jugg and switch to the Classic.

A custom build without a custom feebore ?
Confused.

Why not have a freebore to suit VLD's that you can always lengthen if you must go back to Juggs ?

 

[drags]

5 seconds apiece, 2500 times, is 3.5 hours. Doesn’t seem like all that long, for a good amount of brass.

How long would it take to load 2500 rounds of brass?

 

[joshb]

I’ve always figured that if you want a little more speed over a 308, you got a 30-06. After crawling down this rabbit hole for a few years, I completely understand your motivation! I’m as “nuts” as you are! I have 3 6br, a 6xc, a 6x47 and I just bought a 6 Dasher.
Edit: I forgot the 2 6ppc and the 6mm Remington.
....and a 243

 

[TAJ45]

So you really want to:

"See how far I can push the 308 case."

IMO, going to Palma brass is The Giant Step toward the Outer Limits. Seeing as how you are just kinda Having fun / piddling around for grinz n giggles. This would be fastest for sure awa cheapest. Buy a hundred, see what happens.

 

[Doug Beach]

How long would it take to load 2500 rounds of brass?

Depending on your equipment, needs, and general pickiness, anywhere from a few hours, to several days.

 

[simo hayha]

Bump, Shawn did this ever come together

 

[Beiruty]

308 AI, Why not just neck up a 243 AI case

 

[JimSC]

I would go .260 Rem or if you want exotic .260 AI, both excellent cartridge for F class open. I have a couple of hundred .260 Rems I made from from Lake City. They shoot great, last forever if annealed

 

[Rtheurer]

Here are some thoughts. 1.) You are correct, you will be in F-Open and at a GREAT disadvantage compared to the 7s and the .300WSMs; 2.) You are also correct in that your velocity gains will be minimal. That is why you will be at the disadvantage; 3.) I have shot many, many "Ackleyizied" cartridges. In most cases, you make an Ackley out of something to make a better case design, not necessarily to gain additional velocity; 4.) As long as you are going to go to such lengths, why not go in the direction of something that will NOT be at a distinct disadvantage? Go to a .300WSM or a 7SAUM or 7SAUM improved or something in that realm where you will be at a distinct ADVANTAGE! Just my 2 cents..

And yet.. Fritz BRaun down in Florida would prove that wrong during the V2. LOL... Dude can sling some 30 cal 200's pretty dang good.

 

[ShootDots]

And yet.. Fritz BRaun down in Florida would prove that wrong during the V2. LOL... Dude can sling some 30 cal 200's pretty dang good.

He must be an awesome shot! There is no doubt that if you could read the wind "near perfectly" then a 6Dasher or some such accuracy champion would be the way to go. However, if you are like me and probably 90pct of "everyone else" you NEED to put the odds in your favor as much as possible. Using a .308 for F-Open would not be putting the odds in your favor,,, ergo, WIND READING is the key to high scores. But the shooters like me need a little bit of help..

 

[LVLAaron]

I have a sinclair 30-40 hunter class BR rifle that is effectively a straight wall 308...

If trimming is your concern in .308 - I'd spend 140 bucks and get a Giraud 3 way trimmer.

 

[cmysix]

MMMMM..... improved .308 mmmmmmm hey how about .30-06.