Home Forums Hunting & Shooting Ask The Gunwriters Looking for info on 338-08 Ackley Improved

Powdr.

I spent some more time researching and I can say that analyzing this on QL is VERY time consuming. And it can get a little bit confusing, trying to explain the intimate intricacies that affect pressure, however:

First:

The .338-08 is a necked up .308. The .308 base case is the .30-06 case essentially by most dimensions. The difference between the .338-08 and .338-08 Ackley Improved is essentially the shoulder that has been blown forward and it's angle sharpened to 40 degrees. The length of both the .338-08 and .338-08 is the same 2.014 inches. The difference is case volume is 56 grains H2O normal and 57 grains H20 Ackley Improved. One grain ? Not much "improvement". I hesitate to be too detailed and to confuse the issue but QL is showing the same bullet .338, 200, Nosler Bal Tip, 39595. Using the same charge 45 grains - both well down on the pressure scale in the range of 27,240 psi normal; 32,117 AI. Velocities are not that far apart. Normal 1,977 fps. AI 2051 psi. For some reason QL is showing the bullet seated deeper in the AI - 0.534" and for the Normal 0.334". Same powder charge, same bullets ??? It shows the load capacity normal 99% filling and the AI 106.8% compressed.

I haven't been able to find load data on the internet for the Ackley Improved, however, I did find it for the .338-08.

http://www.loaddata.com/members/search_detail.cfm?MetallicID=463

In my opinion this load data is good enough to use for the Ackley Improved. The two cartridges are very close with the only parameter different in the angle and shape of the shoulder. There are lots of loads and lots of powders shown. Some are too slow and some too fast. Some will produce underperformance and some over performance. I think that if you use these load data tables they will be safe and conservative.

QL says the maximum average pressure allowed is 60,191 psi the SAME for both cartridges. So the above stared pressures using the powder and charge stated isn't even close to max. Thus two things to keep in mind. The powder "burn rate" and bullet seating depths are the critical factors that generate pressure.

Of course you will know immediately whenever you are bumping up against dangerously elevated pressures - i.e. , hard bolt lift, difficult extraction, flattened primers.

Running all of this through QL is very time consuming entailing hours and even more time consuming trying to post all of it. If you can zoom in on some specific powder types and loads from the above load data I can spot check it of you on a few individual basis.

Powder burn rates:

https://www.hodgdon.com/PDF/Burn%20Rates%20-%202014-2015.pdf

Bill I can't thank you enough for the assistance. Yes it is very time consuming and tedious. I presume you enjoy it much like myself. Again, thank you so much. powdr

You should be able to use 338-06 to 338-06AI actual change in powder volume to determine the 338-08 to 338-08AI change. The actual powder change will be the same. The percentage change is different but can then be calculated for the -08. I suspect you'll need an extra inch of barrel in addition to the AI to achieve the gain you're looking for. Do you already have the barrel?

It's a Tikka T3 and I don't know how long the are. I've never measured it. powdr

I'll also add, that at least for the 180s, just use AA2230. That stuff is magic for velocity in the lighter bullets. 180s will be well above 2800, and 160 TTSXs over 3050 in normal 338 Fed with a 22" barrel. No deer or hog (or elk, kudu, ...) will survive that. Factor in another 20 for Tikka barrel length and 50 for AI and you're about there.

Here a few more tidbits that I may as well post also. They deal with the above posted Load Data link for the.330-08 and also the relative Burn Rate chart. The thrust here is to examine the relative safety of the various powders listed in Load Data. I printed each and laid them side by side. Much easier to grasp.

Then on page one of the Load Data I classified each powder shown with it's relative burn rate number on the burn chart. The chart starts with #1 *( Fastest ) and ends with 149 *( Slowest ). Then I used the universal 48 grains of powder, that's a full load, and compared the results with each powder.

The hottest was #76 Accurate AAC-2015. 2,898 fps. But pressure 75,521. Max recommended is 62,000 psi. The next hottest was #79 IMR 3031, 2697 fps, 62,400 psi.

After those two the others listed from #88 to #111 all gave velocities in the spreads from 2,667 to 2,823 and pressures from 50,961 psi to 59,449 psi. That's the mid range.

The lowest were four ranging, below #111, from 2,384 fps to 2,554 psi with pressure ranging from 36,323 psi to 45,039 psi.

Note that all calculations used 48 grains which is a full case load. Thus staying between #88 and #111 shows good velocities into 2,800 fps and pressures safely below max.

Going above #76 requires reducing the charge. Faster powders will work. It simply means that they have to be decreased to avoid over pressuring.

Going below #111 means a full case load 48 grains but slower velocities in the 2,30 - 2,500 fps range and much lower pressures most in the 36,000 psi range.

The comment above about a longer barrel illustrates that in some cases all powder is not burned in the barrel. It is blown out to waste.

In the fine balance between efficiency, economy, performance and safety there are some big winners in the Load Data. And some losers.

All calculations pertain to the 200 grain bullet only. I haven't done any work above or below. In the lighter calibers such as 180 grains the laws of physics say that if you load a 180 grain bullet with 48 grains, max, the velocity will increase and pressures will still be perfectly safe and diminished. Thus the matter then becomes one of bullet selection and application. Flatter trajectory, a plus. Bullet expansion contingent on the design and construction. That spread would be all lead up to all copper solids. Plus size and type of animal.

It is possible to get carried away with of the ballistics, science and mathematics. And I do think that is largely the case. I zero my scope at 200 yards and I don't shoot past 300 yards. I'm not a fan of the Hail Mary's. Bullet placement is the Holy Grail of successful hunting. It is absolutely paramount. In all of my years I have never lost an animal.

Thanks Bill, again a very much thank you. I have several of the powders in the mid-range and that's all I'm interested in working with. Great info, thanks for digging. powdr

Rel 15 is the best powder i'v found for the 338-06 Ack and my preferred bullet is the Swift 210 gr Scirocco . My rifle has a PacNor Match Barrel .

There you go, introducing empirical evidence to a highly theoretical thread.

Lil Gun has been the best for me in the 22 Hornet.

Good one Steely

Thanks prm and everyone else. I've loaded 52gr in a 338F case w/o compression. I feel like w/the improved case I can load 54-56grs but I'll have to see. I haven't received my gun back yet. It should be here in about 6 weeks. I've got some Norma 201, H4895, Varget, BL-C2, and a few others I'm going to try. I'm going to try and pick up some AA2230 per prm's request and some TAC as John has had good luck w/it w/a wide range of bullets. I'm 62 years old and this will probably be my last foray into wildcat country. Just nothing more than loonyism! I'm kinda excited to be playing w/it. Thanks guys for all of the help. As you've probably noticed I'm not totally clueless on this stuff having had at least 5 Ackley's but this one is quite unusual. powdr

Atta boy! Keep the fire burning bright.

both my Hornets get nothing but Lil'Gun , but my 17 Rem gets Rel 15

Yeah Ben, I love fooling w/wildcats and some of the older cartridges like the 250Savage, 257Roberts, and 7x57. Seems like I'm old stuff or new stuff but not much in between. Would love to have a Newton rifle in .256 or an old Mauser in 8mm-06. powdr

pow..,

In the for what its worth department, you arent the only looney.
My buddy is sure he has created the utimate 33. The .338/280AI. We havent run it over screens yet, but it was a bitch to load for.

O

Yeah, I built one myself about 8 years ago. Got a new whim and it went down the road. powdr