284 win AR10

[stagpanther]

I decided to go back and do some more work on my 284 win AR project--I long lost track of this one once my soul was claimed by the .224 valk.

Despite everything you might read--it works just fine out of an AR using conventional xx308 parts, though there are a couple nags that do have to be dealt with--but they are minor issues--unless you intend on making a battle rifle out of it.

The issues are 1) the really high BC/SD bullets might require crimping with the ogive a bit down into the case mouth at the standard 2.81 COL; and 2) because of the dimensions of the .284 case--it's going to put sideways pressure on the magazine beyond 4 cartridges loaded into a "conventional" 308 magazine.


I recently bought a couple of LaRue 308 magazines--which as far as I know are the most expensive ones out there but feature two key features: 1) they are made of steel; and 2) the front of the magazine is seamless--unlike most other magazines which have a lap seam on the their front face. This gives you a few more hundredths of an inch to play with--even more if you are bold enough to cut out part of the front of the magazine--which is what I did and theoretically should be able to get pretty close to 2.3" COL. However--even after getting the extra length for the cartridge, I found there still needs to be a bit of work to be done to resolve the pitch of the cartridge--especially the first one which can pitch down in the magazine if you're not careful on loading the magazine into the mag well and drag the bullet nose on the well wall and hanging it up under the extension. All of that is easy to avoid with careful loading of the magazine--on the other hand this would not be a practical arrangement for a "life or death quick mag drop and load" scenario. No big deal for me; I can work on that later and as long as I load the magazine carefully, the gun does everything just fine with no failures.




I loaded these 162 eldx's to 2.917 and with that the base of the ogive was outside the case mouth. The gun shoots beautifully with these--to be honest the gun shoots WAY beyond my ability at this point, a fraction of a mistake--a tiny little bit of induced movement--and I consistently threw a shot wide in each group. I'm a king at choking when I get a good group going. Obviously that's another area I need work on.







PS--the LaRue magazines--like most of their products--come impeccably packaged ready for the galleries of Macy's. Mine included a bottle of their "dillo dust" meat seasoning--quite tasty actually on your game meat. ; )

[handlerer2]

Impressive! I never would have considered this cartridge in an AR platform.

I own a 6.5x284 and really appreciate it. I don't think it would be suitable for an AR platform, because of the very long bullets.

I like this idea, but where did the notion of this cartridge in an AR come from?
The fevered imagination of a lifelong shooter? I dig it.

[stagpanther]

I like this idea, but where did the notion of this cartridge in an AR come from? The fevered imagination of a lifelong shooter? I dig it.

Not exactly--I was interested in trying something out similar to the FN 284 that was submitted for competition to replace the gerand shortly after WW2. The rest, as they say, is history. I happen to agree with those who think we totally blew it by not selecting the 284 over the 308.

[stagpanther]

I'm guessing at this point that changes in a magazine like making the inner width a bit more narrow to stack the case widths better, the feed lips a bit closer and perhaps a modification in the magazine follower would make a "hassle free magazine." No market demand for this particular cartridge, so I guess that's something I'll have to figure out on my own.

[stagpanther]

The 284 win has become something of a "split personality" cartridge. Most data I've read refer to it as a "short action" cartridge--but the reality is that much load data goes well beyond that. I haven't cast the chamber on this--but I can easily tell the chamber reamed has a long freebore which accommodates COL's to 2.3 and beyond.

The Hornady eld's appear to be "good jumpers" and work well with long distances to engagement of lands--something I noticed also when trying to find good loads for the valk.

The 162 gr eldx has a G1 BC of .630 BTW. That's heady stuff. Berger has a couple of bullets approaching .7 in the 7mm--I bought a box out of curiosity though I have my doubts they can be seated long enough and still work well in the AR's magazine--though might still be interesting in a single feed scenario.

[Mobuck]

Just my opinion: I'd be OK with a 7mm08 and not have the hassle of mag adjustments and/or cartridge OAL.
In fact, if I hadn't caught a good deal on a 6.5C upper, the 7mm08 would have been on my rack.

[stagpanther]

Just my opinion: I'd be OK with a 7mm08 and not have the hassle of mag adjustments and/or cartridge OAL.
In fact, if I hadn't caught a good deal on a 6.5C upper, the 7mm08 would have been on my rack.

That's true--the 7-08 comes close in terms of attainable velocity, but the 284 win apparently has other burn efficiency advantages--at least so say F-class champions shooting it who are "rediscovering" the 284 win. I have a bolt gun in 7-08 and it shoots very well--but not as "promisingly well" as the initial groups seem to indicate above. The magazine stuff is a minor hassle--mostly because it's a "song and dance" to get longer bullet seatings. I had to do the same thing for the Grendel when it first came out and magazine selections for it were very limited.

People often talk about the quality of the barrel and the trigger as the most important factors in making an AR shoot well. Those are of course important factors--but IMHO equally important is how well a cartridge gets cycled into the chamber--meaning getting the cartridge from the magazine to seated in the chamber with the least amount of damage to the cartridge and the seated bullet, chamber and bore as concentric as possible. That can make the difference between an AR that shoots 1.5 MOA or .5 MOA IMO. Again, just my opinion--but this is probably why the valk is having such "teething" issues in getting it to work consistently well--it needs a "graceful" entry into the chamber to get seated as well as possible.

[HiBC]

You already have the 284,I'm not suggesting you do anything else.

For a limited time,Armalite offered an upper in .300 RSAUM. Brother bought one. LOA is not a problem.The case on a 300 RSAUM is fat like the .284. He is able to get reliable feeding .He did put some kind of thin,self adhesive anti-friction plastic strips inside the mag body as I recall.

IIRC,there was a 7mm RSAUM ,and a 6.5 wildcat.

Of course,the WSMs captured the market. The RSAUM brass is not common or cheap.

It is something that has been done

[stagpanther]

You already have the 284,I'm not suggesting you do anything else.

For a limited time,Armalite offered an upper in .300 RSAUM. Brother bought one. LOA is not a problem.The case on a 300 RSAUM is fat like the .284. He is able to get reliable feeding .He did put some kind of thin,self adhesive anti-friction plastic strips inside the mag body as I recall.

IIRC,there was a 7mm RSAUM ,and a 6.5 wildcat.

Of course,the WSMs captured the market. The RSAUM brass is not common or cheap.

It is something that has been done

Thanks for that--I've had the same idea of putting some kind of "constrictor" inside the magazine wall in order to alter the stack profile of the cases. Because the 300 SAUM is actually quite a bit fatter than the 284--did he end up making more or less a single stack magazine out of it? As sideways pressure on the magazine walls go up--the more the magazine swells creating most of the problems. So the "search" is more or less finding the right angle of the case stack that also relieves pressure on the magazine walls.

[HiBC]

I don't know what the strip was.I think slick was the point more than thickness.

I don't think a stagger box mag is easily converted to center feed unless the case is really fat.The follower must offset the first case to make the stagger so one feed lip is active.The space between the lips is more than the cartridge.

[stagpanther]

I don't know what the strip was.I think slick was the point more than thickness.

I get that in theory--but the real issue seems to be overcoming the friction between the cases themselves which create a wedging force.

[stagpanther]

More experimentation has resulted in a surprising discovery--turns out the magazine so far for adapting to the 284 win in an AR--for me anyway--has been magpul's PMag. It does a better job than any of the steel ones of tried in keeping the cartridge from tilting--a problem that occasionally caused the BCG to ride over the magazine and miss chambering the cartridge. The other bonus is that modifying the front to take an "oversized" OAL is much easier to do than with a steel mag. So there you have it.

I ordered a couple of boxes of 180 VLD hybrids and nosler's new 185 RDF to try out; realizing they are both likely borderline in the 284 win cartridge. My McGowen barrel was cut with a 9 twist, so I thought I might have a chance.



My set-up handles an OAL of 2.9 with no problem, so I went ahead and made a "mini ladder of lower-end charges, just to see if there was any potential hope.

Unfortunately I went out into temperatures in teens and a wind chill down near zero--and I was underprepared not having gloves. I shot quick to beat feet, further complicating the results I was shooting a reactive target that was layered upon many other targets, it seemed that the paper stiffened and shredded a bit much making it hard to tell where the impact actually is. It's also possible that there might have been some key-holing going on--these were likely borderline velocity/stability for the bullet weight. Here's 47.5 grs of RL19 driving the 185 RDF; the group could be a bit smaller--or bigger--than what seems to an otherwise fairly promising group.

[stagpanther]

Nosler's 185 RDF on the left--Berger's 180 hybrid VLD on the right.

[979Texas]

Love the idea of this gun, particularly your choice of caliber and platform combination.

[stagpanther]

Love the idea of this gun, particularly your choice of caliber and platform combination.

Thanks--it was a "burning curiosity" thing for me too.

[stagpanther]

Went out again today--conditions were still very cold and windy but still managed to get a couple of nice sub-MOA groups with the 185 RDF's. However, all groups generally had at least one key-hole shot, even though I figure my warmest loads were approaching 2600 fps. The AR lower's magwell simply isn't going to allow a COL of much over 2.92--so I'm unlikely to reach a good stabilization load. Reluctantly, I'm going to abandon this bullet and move down to the Berger's and see if I have any better luck with them.