Hello,

I have decided to have a .308 barrell chambered in .30-06AI.

Can anyone tell me what the increase in internal volume will be for this round compared to the parent case?

Want to play around a little bit with quickload to see what kind of performance to expect from this round!

Regards,
beefeater

The increase will be around 5 to 7% I believe. IMHO it is not worth the trouble.

My data shows a 3.7% or 2.6gr increase. It has been my experience that at the same pressures you will gain about 1% velocity for each 4% increase. So 25-35fps. Bigger gains come from increased pressure over the parent.

Mark makes an excellent point below. If you have a 308 barrel and want an increase to me the 308AI makes no sense. Not worth the expense and effort. The 30-06 will not clean up the chamber. So that leaves you with the 30-06AI, another improved, wildcat or alter your action for a magnum.

After playing with numerous AI over the last 30 years to me the gain was never worth the effort. That said the majority of my rifles are full wildcats on a blown out 280 case. For the same maney you can get 7-10% capactiy gain vs 3-4%. If I was going to the trouble of rechambering for a velocity increase I would go all the way and consider something like the Gibbs, Hawke, AHR if I wanted to stay nonmagnum. Only thing you lose is the ability to fire a factory round. You fireform anyway and the extra cost of the dies is small in the overall picture.

It may not be enough of an increase over a standard '06 to be worth the trouble, but it probably will be enough of an increase over the 308 to be worth the bother. And since the Ackley version will clean up the old 308 chamber and the standard '06 won't, everything else is academic.

the gain going from a .308 to a 30-06 and a .308 to a .30-06 AI is almost exactly the same!

In your case the AI chamber is needed to clean the old chamber!

Personally.....I'd install a new barrel or a take off barrel and then you can chamber to anything at all!

Think about this....place a .308 round next to a 30-06 round and just look at the difference! Then look up the performance differences.....

Small isn't it!.......and we have folks that think the incredibly miniscule increase from a 30-06 to a 30-06 AI will gain them even more!

This isn't rocket science!

quote:

Think about this....place a .308 round next to a 30-06 round and just look at the difference! Then look up the performance differences.....

Small isn't it!.......and we have folks that think the incredibly miniscule increase from a 30-06 to a 30-06 AI will gain them even more!

Ok what is the idea putting facts and logic into play this early in the morning????

Lets see using the capacity in Loadtech for the 06 & 308 I have 69.9 and 57.4 that is a 21.78% capacity increase. Taking the max velocity listed in the Nosler #4 for each with a 180gr bullet I get 154fps or a 5.67% increase. If I divide 5.67 into 21.78 I get 3.84. So for each 3.84% increase in capacity I got 1% increase in velocity. Using the 3.7% capacity increase the AI gave me over the 06 I should the get .96% velocity increase for the AI. In this case 27.6fps.

I have close to 30 years of actual data that gives me the same result. Rule of thumb 1 for 4. Huge gains from the AI are from pressure not capacity.

Vapodog I guess to strange minds think alike.

Hi again, and thank you for your replies!

Maybee I wasn't very spesific.
I want to rechamber a 28" .308win barrell sitting in a M98 action. The choice of AI over standard .30-06 is as Ramrod and Vapodog points out to clean out the chamber.
With increase in volume over the parent case I meant from .30-06 to .30-06AI.
I will plug a 3.7% increase into quickload for my initial playing around with numbers.
I could keep it in .308win, but I want to use a case that utilizes the length of the action. Magazine and feeding will have to be adjusted too.

quote:

Magazine and feeding will have to be adjusted too.

The changes needed for the 308 aren't much. If you look at the various MKX, Daly etc. They simply put a small box in the back of the magazine and a shorter follower. Everything else is the same.

If you enjoy spending your time trimming brass then the 06' is a fine case. I like to shoot, and that's why I feel the AI version is the superior round, not because of the slight gain in velocity.

quote:

If you enjoy spending your time trimming brass then the 06' is a fine case

I've heard this comment for years. Please remember the majority of my cases are full blown out cases with the shoulders moved forward etc. I've delt with triming this way. When you fireform the AI case will shorten so you get more time before you need to trim. In my 280&340PDK when I take a new 280case at 2.54 fireform I end up with a case of 2.495-2.5" at 4-5 reloads I'm back at 2.54. For my non improved cases. I buy 100 new cases run it through the FL sizer then trim by .05" before the first loading. Yep back to the AI length. Then rotate through all 100 cases at 4-5 loading I'm back std length. In either case I can't ever remember needing to trim more than twice. Usually once for non improved and never for the improved. But in the improved I have to fireform.

I'd much rather shoot than trim as well.

quote:

Originally posted by pointblank:
If you enjoy spending your time trimming brass then the 06' is a fine case.

Yes, please explain this.
My 30-06 (standard not AI) brass has over 20 full power loadings on it, and it's been trimmed exactly twice, once during initional prep, and once after 15 loadings. Of course I'm not running some slophole factory chamber, but a minimum spec "match" chamber, which may explain why I don't see the need to trim very often.

How far back do you guys keep the neck length from the end of the chamber? I too use match chambers and know how long they are. I make my cases .010" short or the chambers length and even with improved cases, I can't go 15 firings without trimming. They won't ALL grow too long, but I wan't all my cases a uniform length, so I trim when a few cases get to just .003 from the end of the chamber. In my experience, the drastic taper in the case as well as the shoulder angle in the standard 30-06 as well as other cases of like design, lends to faster case growth with every shot, and sizing procedure. Cases of this old design are great for feeding in many different styles and configurations of firearms, but are far from efficient when it comes to ignition and powder burning. The sharper shoulder as well as straighter walled case of the improved version make for a more accurate chambering, due to the improved combustion chamber. This is of course just one man's opinion, and I for one don't like running with the masses.

If the real world is of any interest I get 2950fps from my 24"30-06AI (done to clean up a Mauser 66 chamber. I don't use it as a "muck around" plinking rifle but when I fire two shots at paper they always overlap 50%.

mike

quote:

How far back do you guys keep the neck length from the end of the chamber? I too use match chambers and know how long they are. I make my cases .010" short or the chambers length and even with improved cases,

All my improved cases will shorten on firing by about .05" from factory length if not I will shorten them as well as factory cases by that amount. I have 100 cases for each rifle. I then will use them in rotation triming again when the length gets within .01" of the end of my chamber.

In factory rifles I have tried trim to the same length vs various lengths in the same groups. I saw no difference.