Home Forums Hunting & Shooting Hunting Rifles 338-284 vs. .338RCM vs. .338-06

I have been following discussions of the various non magnum .338 ctgs. with interest. I have a .338-284 in an Alpha Arms Alaskan and really like the gun. In checking loads at Loaddata.com, it seems that the .338-284 out performs the other two ctgs. I know the 284 case reportedly has about the same powder capacity as the 30-06 case, but the shorter, fatter configuration may be more efficient.

200 gr. 225 gr. 250 gr.
338RCM 2,800 2,600 2,450
338-284 2,880 2,780 2,600
338-06 2,740 2,640 2,530
338-06AI 2,800 2,640 2,550

These data were gotten from Loaddata.com, picking the fastest published velocity for each round at three bullet weights. Although the 338-284 is pretty close to the 338-06, I wasn't expecting to see it performing slightly ahead in most categories. I'm not sure about pressures, etc, or the details on how these loads were developed. Just thought I'd post these velocities. In 338-06, the AI version doesn't seem to run that much faster than the std. 06 case. I'm sure others have their data. I briefly reviewed currently published data, looking for the hottest loads to compare these three rounds.

DF

I had these data in a nice, easy to read form, but when it went to the Forum, it was all clumpped up, hard to read. I did an edit and again the nice format was seen. When I clicked back to the Forum, this is was you see. Sorry about that. Not my fault.

DF

The key would be at comparable pressures. I certainly know that I have gotten a 338-06 to go faster than the load data you post, without any evidence of pushing the envelope. And since the 338-284 is a wildcat, there is now pressure standard.

Then variations between barrels comes into play; I have seen 100fps variation between rifles in the same barrel contour.

But all three are close enough to be peas in the same pod.

Utah,

What's your experience with/knowledge of the 338-06 vs. the 338-06AI. Looks to me like there should be more differential than Loaddata is showing. Just makes sense, more case capacity, more velocity. And, what bullets do you prefer and how fast do you push them?

I was somewhat aggrivated by the way the Forum format jumbled up the data chart that I had gone to some effort to make easy reading. Oh well...

DF

The 338-284 has the SMALLEST capacity of the 4 cartridges mentioned.
Therefore with all other things being equal (they never are in reality) the 338-06AI would be fastest, then the RCM, then the 338-06, and finally the 338-284.

The AI has nearly 6 grains greater capacity than the 338-284.

I always liked the idea of a .338 x .284. I'd say one of those running 185gr TSXs would take care of anything I'd ever need, and do so with authority and manageable recoil. Pronghorn to moose, duiker to eland.

Should make a handy, potent package in something like a M70 Extreme Weather or Featherweight and a 22" tube.

Dirtfarmer,

How long have you had your .338-284 and have you done much load workup or hunting with it? I'd be interested to hear your esperiences. When looking to rebarrel my Rem 700 LA I was very seriously contemplating the .338-.284 but at the last minute found some 6.5-284 Redding Comp bushing dies for a great price on Long Range Hunting from a guy and took that as a "sign from above' that I was supposed to have a 6.5! It helped that I've always been a big 6.5 fan, though (and brass was an easier proposition).

Anyway, I really like the .284 Win platform, both the parent and its many offspring, and it's interesting to hear from a guy who actually has a .338-284. BTW, is your rifle a long action? I personally think the .284 Win family cartridges shine in a long action so you can seat those long, heavy-for-caliber bullets way out there and leave room for lotsa slow powder!

Mojo,

I traded for the .338-284 several years ago. I convinced the dealer that he would never sell such a wildcat to anyone but a hard core reloader like me. I traded a lesser grade Alpha Arms .270 for this Alpha Arms Alaskan in .338-284, even swap. The Alpha was the brain child of Homer Koon, of Ranger Arms Magnum and Omega III rifle fame. The Alpha's were produced in the Dallas area from '83-'87. Reportedly, Mr. Koon used Douglas air guage barrels and designed a "V" block bedding setup where the round action sat in aluminum blocks behind and ahead of the mag. box. The tang and trigger assembly floated behind the rear block with no screw. The bolt lugs lock into a barrel extension machined into the barrel blank, not unlike a shotgun with barrel extension. So there's no practical way this gun could ever be rebarreled, as no one would have the jigs and machinery to mill the barrel to receive the bolt lugs. Good news, it shoots as is and the stainless barrel in such a caliber will never be shot out.

Best loads out of a number of combinations are:

180 gr. Accubond, 53 gr. RL-15, 3/8" group at 100 yds.
160 gr. TTSX, 57 gr. Varget, 5/8"
200 gr. Combined Technology, 53 gr. Varget, 3/4"
185 gr. TSX, 54 gr. Varget, 7/8"

Combined Technology bullet is essentially a black Ballistic Tip. I didn't chrono. The 160 gr. load should be pushing 3,000, the others on down to around 2,850 for the 200 gr. from 22" bbl. Easy shooting gun, no pressure signs. It's a short action which seems to work well with this ctg.

With my 6.5-284, I used a standard length action so I could load Bergers and other bullets longer. That doesn't seem to be an issue with the .338-284, at least with the bullets I've tried. Haven't tried bullets over 200 gr. as I'm not bear hunting.

DF

Dirtfarmer,

Thanks for the info. Very intersting. I hadn't heard of Alpha Arms rifles before. Sounds like a fascinating setup and quite unusual. My 6.5 has a Douglas XX air-gauged SS barrel and it shoots superbly! Course, with as much as I shoot it and the velocity I'm pushing, it probably will need a new barrel sooner rather than later.

Any chance you have pics of the rifle? I'm curious to see it.

Mojo,

After Photobucket went high tech, I can no longer get my photos uploaded to a forum. Too complicated with all the new options, phone apps, Tweeter, etc. Need info on other sites from which to upload pictuers to this forum.

Would appreicate help from Forum contributors.

DF

Cameraland has a photo hosting feature and it's free.

Is that 6grs capacity considering combined overall length with bullets seated to magazine constraints? I think when you load both to magazine length with the same bullet you will get more capacity from the 338-284. The shorter case has less capacity displaced by the bullet shank when both are loaded to LA mag length of say 3.3

BTW that is just my experiance with some other .284 cases vs 06 cases, might not be the case here with 338.

It is my understanding that the 338-284 will run head to head with the 338-06 with a few less grains of powder. So, it's more than just brute case capacity, although that is a very big factor. It's also case efficiency. With the newer powders, more can be done with the smaller, fatter ctgs., thus the high performance of the WSM's, et. al. Now, they may run at 65K pressures vs. 60K or less for the older ctgs. If older ctgs. are pushed to an equivalent 65K+ pressure level, then it's another ball game.

DF

IMO there is no such thing as a more efficient case design with respect to velocity.

It's all about pressure and given equal pressure the round which burns more powder will produce higher velocity.

+1

Well, what about cases of equal capacity, i.e. 284 and '06, both necked up to .338, and running equal velocities, the shorter, fatter case doing it with a few grains less powder. Wouldn't that be a function of case efficiency? May not be a big difference, but seems to be some.

DF

Less volume, less powder is need to make equal pressure. Same bullet weight and design and same pressure means same velocity. There would not be enough difference between the 284 and 06 for anybody to choose one over the other based on velocity.

In 6.5x284 vs 6.5/06AI I ran into a situation where I was loading more powder into the .284 case than the 06 because of the amount of bullet shank intruding into the 06 case. They ran almost equal velocities, does that mean that the 06 case is more efficient than the .284? No, it only means that they had like pressures.

Alpha Arms Alaskan 338-284. Band front sight. Express rear with one flip up. SS action and bbl with Nitrex finish on non SS parts. Model 70 type three position safety. Barrel band front sling stud. Short throw bolt. Now wearing Zeiss 3-9x40 in Warne QD mounts. Now that I've been able to work with the new Photobucket format, will try to post updated photo with scope mounted.

DF

Beautiful and totally unique, Dirtfarmer. I love it!