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By Joshua Gillem

Every so often, something comes out of the firearms industry that forces you to stop and think, “Why has it taken them so long to fill this gap?” I’ve had the privilege to say that I’ve had my hands on one of those firearms during the course of the last few weeks and every time I show it to a new gun enthusiast, they agree with that sentiment. I’m talking about the Olympic Arms MPR308-15M. But, before you roll your eyes at the photos and pass this along as “just another AR” review, read on because as far as I can tell, there isn’t anything else like this on the market. You’re looking at a rifle capable of firing two totally different calibers . . .

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When I first heard about this rifle, my heart skipped a beat. Could it be that I could have the best of both worlds; the venerable .308 Win and the fun-shooting (and cheap) 5.56 NATO? In one rifle? As my imagination conjured up some ideas about how they did it (and how much fun this review might be) I was giddy, like a little boy on Christmas morning. Alright, I wasn’t that excited, but you get my point.

Olympic Arms had some hurdles to clear during development, but what they sent for me to test was one serialized lower, and two uppers. The MPR308 – both medium and carbine length models – comes from the factory with just a .308 upper. You’re then free to buy the 5.56 upper of your choice and bolt one on as needed.


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Overall, the rifle is sexy, and works well. And hey, you can never have enough rail space, right? I mean, I can mount a flashlight, a scope and after someone invents a Picatinny mount for my Android, I’ll be able to mount that, too.

Unfortunately, the 5.56 upper Oly sent me for testing purposes looks as if it just gotten back home from a tour overseas with my boys in the Fightin’ 6th. Getting the front sight post to turn was almost an impossibility, and there were definitely some rusty spots that I needed to dispose of before I would even let myself mount it on the lower.

Again, this upper was just a mil-spec test piece that is not actually included with the price of the rifle. Only included it so I could test that the gun works with both calibers. And, for the most part, it did.

The technical guru I spoke to at Oly forced me to read the owner’s manual and I’m kinda glad he did because the first round of disassembly and reassembly would have been interesting without the knowledge I gained from it.

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Rather than the conventional method of removing the rear takedown pin and pivoting the upper receiver, both pins need to be removed. That allow the upper and lower to slide away from each other in order to clear the buffer tube extension that protrudes into the bolt carrier. And, when re-installing this same upper, just reverse the process.

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At first, I thought I was doing something wrong because I couldn’t get them to separate. I realized that I had to act like the Shaq in his latest Gold Bond commercial and give it a little shake in order to get the buffer tube extension out of the bolt.

After the learning curve was over, disassembly and reassembly went much more smoothly.

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Takedown is much more similar to what you’re used to when the 5.56 mil-spec upper is mounted. However, you’ll have to get used to the buffer tube slamming forward, because it doesn’t sit inside the 5.56 bolt carrier like it does on the .308. You’ll also need to move the pivot pin to the other hole in order to fully secure the upper receiver.

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The magazine well is channeled out to take a proprietary single-stack 10 round magazine, as well as your average 5.56 AR mag. However, I’m not positive that loading the single stack .308 magazine to capacity is a good idea, because I did experience a few malfunctions whenever I maxed it out at 10 rounds. I found that the magic number was seven rounds. Whenever I reduces the number in the mag, I experienced no malfunctions whatsoever.

I’m not sure exactly what caused the MPR308-15 feeding failures, but suspect that the issue is with the magazine itself. That could dissipate over time as it’s broken in. Still, when I pull a weapon out of its box, I expect it to fire flawlessly each and every time I run it. Otherwise, what’s the point?

MPR308 with proprietary .308 magazine inserted

Accuracy was exactly what you’d expect from a rifle chambered in .308 Winchester with an 18” stainless barrel and 1 in 10 twist.

I used the (overkill) SHV 4-14X56 NightForce optic (review to follow) to throw my projectiles down range. Sadly, I didn’t capture any target photos, so you’ll just have to take my word that this baby dances around inside (and just outside, for those questionable trigger pulls) the bullseye at 100 yards. I’d peg the rifle at 1.5 MOA shooting the provided .308 upper. Speaking of the trigger, there was hardly any slack, and it’s just what I’d want in any of my rifles.

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Overall, I’m impressed with the build quality of this rifle and the ingenuity of Olympic arms. This Multi Purpose Rifle’s MSRP is right around $1560.00 mark, which is surprising based on the amount of research and development that must have gone into making a successful prototype.

I can already anticipate the comments: “Yeah, but owning more than one gun is where it’s at, so what’s the point?” And, I really can’t disagree with you. After all, I’m a gun nut, just like the rest of you. However, I’m thinking about the dude who wants to shoot, but can’t afford more than one rifle because he’s got a new kid on the way. A rifle like this affords that gun the opportunity to be able to shoot a decent rifle for a $1300 street price.

MPR308 with standard 5.56 magazine inserted

And once the zombies start munching our brains, my guess is that we’ll all need rifles chambered in more than one caliber – ya know, just in case you run out of a particular cartridge. When that happens, all you need to do is take the 43 seconds (yes, I’m a nerd and timed myself just to see just how long it takes) necessary to mount your other upper receiver to start throwing some more lead at them.


Caliber: .308 and 5.56 (rifle comes with .308 upper)
Barrel: Match grade 416 steel 18″ button rifled bull barrel (1 in 10 twist)
Length: 42.75: overall
Weight: 9.0 lbs.
MSRP: $1,558.70

Ratings (out of five stars):

Accuracy: * * * *
After I sighted this rifle in, it was deadly accurate out at 100 yards.

Ergonomics: * * * *
There are enough rails on this thing to let your imagination run wild. The adjustable stock helps the rifle feel bigger, which helps given my XXL size.

Reliability: * * *
When the .308 magazine is loaded to capacity, I experienced numerous failures to feed. Load it a couple of rounds short and all is well. Fully-loaded 5.56 mags ran just fine, all the time.

Customize This: * * * *
The fact that I can shoot .308 and 5.56 from the same serialized lower is a big deal. Oly has also said that this rifle accepts just about any other mil-spec upper, in a host of other available cartridges. But most shooters are going to have a hard time swallowing the fact that there are no other options for the .308 magazine. You get a 10 round mag, that, at best only works right ¾ of the time when fully loaded.

Overall: * * * 
The reliability issues may straighten themselves out over time. I put a couple of hundred rounds through this thing because of the limited time it was available. But, the fact that I can shoot multiple different cartridges out of an accurate and ergonomic rifle help keep the overall rating higher. There’s something to be said for that kind of flexibility. I only wish it ran .308 more reliably when fully loaded.

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      • reviewer years ago said they visited oly arms factory and the place was a pig stye ,,and after those idiots came out with the 7.62×39 pistol and got the steel core ammo banned ive been hoping they would go under ,, 4 people ive known have bought their junk products ,all inferior piles of steaming trash .olympic arms is an industry joke .

    • Seriously, this looks like a dud.

      Author says “well at 1300-1500″ you can be slinging lead for those budget minded folks….” Ok, but for 1300-1500 I could buy a really nice rifle or a decent bolt action 308 and an AR.

      And it’s unreliable? Yeah.

      • No doubt. Especially since that $1500 doesn’t include the second 5.56 upper you’d need to make it two-caliber capable. Just buy two rifles for that kind of money.

  1. All that time and money on R&D and its .308 instead of 7.62 NATO and proprietary mags to boot!
    Think I’ll wait for the next version or some other manufacturer to come out with something better.

  2. Sounds cool, and I like the concept. It doesn’t really help the budget conscious shooter however. 1300 dollars plus you still have to pay hundreds more for another complete AR upper (maybe 16-1700 dollars total). The buget shooter could easily pick up a basic AR ( like the Ruger) for 600, a 10/22 or Marlin60/795 for 200 or less, a Mosin or used hunting rifle for around 200, and basic shotty for around 200 (1200 total) and still be less expensive and better equipped than you would be with ths rifle. Throw in a decent handgun for another 400, and you have five guns instead of one for 1600ish.

    Still, this is a cool concept.

  3. I’ve built and sold Olympic Arms rifles since the mid-80s, and while there have been many varying opinions in the shooting community from time to time regarding their build quality, I would like to point out they were way ahead of the game at a time when all the other boutique manufacturers were just a gleam in somebody’s eye. I’d even go so far as to say they were the first major innovators in the AR field. Bob Schuetz, founder of the company, was a former apprentice to the famed custom gunsmith and wildcat ammunition designer P. O. Ackley. It was always a pleasure discussing ideas and future concepts with him. I’m glad to see they haven’t lost their inventive touch.

  4. I bought an Oly Arms 556 once. After I put about 1,000 rounds through it, it fell apart. Jams misfires, failure to feed, it was a mess. I brought it back to Olympic arms directly about 5 times. Spending about $150 or so each time. Never worked correctly again, so I sold it and got my current AR. This may be just my bad luck, however I will own another again because of it. Yes I cleaned it after each shooting session. In my personal opinion, I would say stay as far away from them as possible. Oh and by the way I live in Olympia WA where they are made. Saposedly.

  5. I used to work in QA with a guy who now works at Olympic Arms as an assembler. His work was shoddy at best when we worked together; I can only hope his work ethic has improved now that he makes a product that has more deadly consequences.

  6. I’ve got a DPMS LR-308 that cost $1199 at Cabellas. There are any number of $600 5.56 ARs out there as well. My guess is that if you are buying both at the same time, you could do a bundle for around $1500. Similar money to this Olympic hybrid thing.

    Then you’ve got two rifles instead of one. If you break one, you’ve still got the other.

    I’ll pass on this one.

  7. I wasn’t a fan of the Colt 901 when it came out, not into the “go from 308 to whatever” with a second upper idea, but it seems like a much better thought out product than this thing-

    1. Uses DPMS pattern magazines for .308, and GI for 5.56

    2. Buffer doesn’t stick into bolt carrier making assembly/disassembly more difficult

    And from what I’ve seen the Colt street price is only a couple hundred more for their expensive version, and the same for their cheaper versions

  8. Cool engineering but ultimately, probably not a good rifle for anyone. Who wants proprietary 308 mags when everyone and their brother is making affordable DPMS-patter mags (including Magpul)?

  9. This is just several years too late. You can build a good quality 308 ar from psa for $800. You can buy an entry level ar15 from them for 450 bucks. Most people build ar’s these days not buy. You need to do something really innovative to get me to buy versus build, i was tempted by dpms g2 rifles but passed. I dont think i will be able to resist a 223/300 blackout sig sauer sbr with folding stock….in the ar game u gotta do something the average neanderthal cant build at home…someone build a dedicated 300b suppressed barrel. Or someone come out with inexpensive 300b ammo….

  10. The gadget nerd in me loves this but I take issue with your point about it making it more avoidable to have 308 and 223 because the cost of a few spare proprietary mags will quickly add up to the cost of a separate 223 lower.

  11. Thanks Josh, good review. Not my cup of tea, but worth reading to see whats going on, for when time comes for another weapon.

  12. I’m no expert on Ar’s but this looks awful to me. AR prices plummeting and 308 under 1000. And I have never heard any good about Olympic. Check out Gunbroker-I am shocked every day(wish I had some $)…still a good review.

  13. The concept is interesting, but then again so is the Taurus Curve. The idea of a multi-caliber lower is appealing, but the proprietary 7.62 magazine and weird buffer setup are big downsides and the value proposition is iffy. For $1500-1800 I can get a basic DPMS, Palmetto State or Windham 7.62 AR plus a cheap 5.56 AR which gives me two completely uncompromised rifles, and because I have 2 complete rifles, anything breaking in the lower doesn’t leave me with nothing to shoot

  14. Thanks Josh,

    I feel like I’m just echoing what everyone else has said but somehow I still feel compelled to. The proprietary 10 round magazine that only feeds when you load 7 sucks and kills the whole project. If you really have to have a rifle like this, the colt 901 costs more, will need a trigger, uses an adapter piece which is apparently not necessarily included in the price and has a mostly proprietary upper, but at least it uses normal magazines. If you want to shoot 308 and 5.56 buy an AR-15 and a DPMS (I like the G2) or a 308 bolt gun or something. This doesn’t really buy you anything.


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