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.300 OSM - .243 WSSM - .25 WSSM in AR-15

Discussion in 'Rifle Country' started by HarcyPervin, Dec 16, 2010.

  1. HarcyPervin

    HarcyPervin Well-Known Member

    I was reading up on some other calibers in the ar-15 upper and I came accross these, the .300 OSM is claiming 30-06+ performance out of a ar-15 upper. I was wondering if anyone had looked into this round or the .243 WSSM or .25 WSSM also chambered in ar-15 uppers by Olympic Arms. You can find them on Olympic Arms' website under the Game Stalker product listing. http://www.olyarms.com/index.php?pag...mart&Itemid=37

    Thanks for any input.
  2. kludge

    kludge Well-Known Member

    Betcha it won't do it with 180, 200, or 220gr bullets. Case capacity is equal to .308 Win, which also matches .30-06 with 150gr bullets.

    But yes, doing it in and AR is cool.

    I did a Savage .358 WSSM this year, but I seated the bullets out and COL it too long for a AR-15, might fit seated to the cannelure though. I'm exceeding .35 Rem by ~300fps and I'm close if not matching .358 Win. It isn't going to touch the .35 Whelen. No way.
  3. Abel

    Abel Well-Known Member

    Does anyone make a 35 Rem. upper for an AR15 lower?
  4. kludge

    kludge Well-Known Member

    It's a quarter inch too long, or so. It would work in an AR10 length action, but would require a different bolt.

    AAMOF the .35 Rem was designed to be a semi-auto cartridge.
  5. jerkface11

    jerkface11 Well-Known Member

    I've got the .25WSSM and it easily matches .25-06.
  6. HarcyPervin

    HarcyPervin Well-Known Member

    yeah, I'm looking to get a solid deer rifle that I can also, by slightly modifying, take varmint hunting/plinking etc. So far I'm leaning towards the 6.8 SPC. The AR-15 is such a great package, and being able to spend a few hundred bucks and turn it from a deer rifle (OSSM/WSSM/6.8) to a long range tack-driver (.223) or even an extremely fun, cheap plinking round (7.62x39). I like the AR-15, a lot, but I'm not married to it so I'm always open to a better idea, but this seems like a gun that could fill a lot of roles right away and for a long time in the future, just looking for a little guidance at this point as far as which caliber will be the best for what I'm trying to do.
  7. jerkface11

    jerkface11 Well-Known Member

    The WSSM uppers make for a pretty heavy rifle so if you're not stand hunting I wouldn't recommend it.
  8. lilquiz

    lilquiz Well-Known Member

    Yes I have a 300 ossm. It is shooting a 150 grain at 3050 fps and a 175smk at 2800 fps.I have the bbl version, yes it is a little heavy. After hauling the"pig" around in Desert Storm. I don't mind heavy, if heavy gets the job done;)
  9. 1stmarine

    1stmarine Well-Known Member

    These are very interesting camberings and a great option for many but there are issues. They are ok as soon as you know what they are:

    - With good care and reloading techniques the WSSM cases are extremely durable. I know some folks did a torture testing and were able to reload the same piece of brass 30 times even shooting with AR.
    - The rounds are very powerful. The claims of speed records and power records over .308 and .30-06 have some foundation but when compared with average .308 and .30-06 loads. Those can be pumped up too.
    In any case the OSSM loads that claim those speeds are not accurate. The barrel density in an AR platform doesn't allow for those type of excesses.
    I would be more worry about finding a nice milder and more accurate load than getting any new record.
    - There is one more option that is not listed below that is the 30-25WSSM. it is nothing but the .25 WSSM necked up to .30. The advantage is that this uppers are a tad more accurate and can shoot both the OSSM and the 30-25 WSSM loads. The OSSM cannot shoot the 30-25loads.
    - Some folks get many feed issues but some others don't. Do not be surprised if you get them but they can be fixed.
    - Potentially the WSSM extra raw power could be put to good use if it wasn't because there is no way to seat the best bullets w/o running into COAL issues. Because the best bullets cannot be used this presents serious limitations where the extra energy at long range could be used. In the end we do not need to kill the deer twice at shorter ranges.
    Check all the ballistics charts before you decide if you want to take long shots. The information is out there.
    - Folks with a lot of experience are having trouble getting the uppers to produce MOA accuracy. Sub-moa can be achieve but it is not excellent.
    It is not an issue for the average hunter at 100-300 yards but at longer ranges it becomes a bigger issues, with some exceptions.
    - While some folks are happy with the OSSM many folks are not so happy and the ones that used the 30-25 WSSM are getting better results than the game stalker anyway.
    - While the 6.8SPC is a great option for 100 to 300yards then it suffers some of the same issues of the big bore low grain combination. It is a great option for most folks but if you have to take long shots consider other options. look at the ballistic charts and then decide.

    The AR-15 was originally designed for the .223 round and not the other way around. While we enjoy many great options for this systems we need to understand the physical limitations of it.

    My comments here are not to degrade or critizice any options. I put them here after long research and to the best of my knowledge so others can use this if they want. Do not take anything to hearht. What works for me might not works for others based on different needs, likes of dislikes.

    I am currently working on this thread to see if we can come up with a good long range option in WSSM but we have been hitting the wall with both accuracy and poor bullet selection due to the physical limitations of the AR-15 magazines and the maximum length allowed for good bullets to fit in them.


    One somebody says I have the most powerful round ever think..... sometimes less is more in the end.

    I hope this helps.

    Last edited: Jan 21, 2011
  10. lilquiz

    lilquiz Well-Known Member

    Thanks First, I thought I had seen you there. There are two different options for the ossm , the game stalker which has a stepped barrel for hunting and th k8 mag upper which has the bbl. The game stalker has not had a load developed that will shoot the moa required for long range. The k8 is shooting accurate loads at 2800 with 175 smk . It also has 150 fmj shooting 2600 and 3050 fps giving 1/2 to 3/4 moa. It is giving the same perfomance as any other rifle, depending on the upper. It is however a project rifle, with alot more tweeks to be done.
  11. 1stmarine

    1stmarine Well-Known Member

    First of all many thanks for your kind and prompt reply. How did you manage to seat the 157SMK w/o stepping into the ogive? We tried many magazines and we cannot come down to increase the .70 length difference w/o stepping into the ogive.
    Did you modify your mags?

    This has a lot of potential but I believe the OSSM claims for "da most powerful AR-15 round" is a marketing stunt. Personally I am looking first for accuracy and versatility and not any world speed records at the muzzle. This boils down to the simple formula of high grain, high BC bullets that fly well vs low grain, low BC bullets that come out very fast but with the 'landing flaps' down. lol!

    Everything starts and ends with a bullet. hopefully a good one.

    This would be a nice goal with a barnes TTSX 180gr but so far the COAL is not allowing....

    Range Velocity Drop Energy Drift
    0 2750 0 3023 0
    100 2558 2.65 2615 0.34
    200 2380 10.63 2264 0.98
    300 2209 24.79 1950 2.09
    400 2045 46.11 1672 3.72
    500 1889 75.78 1426 5.94
    600 1741 115.22 1212 8.82
    700 1602 166.16 1026 12.42
    800 1474 230.64 868 16.82
    900 1358 311.08 737 22.08
    1000 1257 410.28 632 28.24

    Pretty decent to take down deer past the 700yds. A experienced hunter with a good 30-06 system could pull out the above but the OSSM cannot at least at the moment due to accuracy and COAL issues.

    Another option that we are considering is to increase the barrel tune by cutting off the barrel to 20 or 21". This means more accuracy nodes. This is based on this old principal.... http://www.tacticaloperations.com/SWATbarrel/

    Definitely these uppers could be fun but are not for the average folks that do not want to fiddle or do not have time.

  12. lilquiz

    lilquiz Well-Known Member

    Have you tried the cammenga easy mags. They will let you seat to about 2.29 I seat at 2.28 and 2.285.This allows me to use all the vld bullets I have come across.I have also found these mags easier to modify to seat around 2.3. I have not shot these seated to 2.285 , I am using load data posted on another forum
    Last edited: Jan 22, 2011
  13. 1stmarine

    1stmarine Well-Known Member

    Many thanks for the reply. Still it doesn't add up. Yes with the cammega we gain some nice real state but so far after converting the magazines we have been able to get .61 maximum when we need .71 and .75.
    How did you manage to seat the 175grSMK properly? Do you have any pictures with the round and caliper?
    Some folks have a achieved by seating the bullet and running over the ogive and while they seem ok with this for me this is a big NO NO.
    There are certain things one shouldn't play with. This is warning in big red letters in any reloading book in the world and that's for a reason.

    Any further information on how this can be achieved it would be greatly appreciated.
  14. 1stmarine

    1stmarine Well-Known Member

    While doing more testing with the WSSM I did some other research and I found that the 30Reminghton AR is not bad as most folks initially thought.
    I posted this article to see if someone can assist and we can have one round reloaded with a high BC bullet. Unlike the WSSM here the math actually works with this round and also in the ballistics software shows pretty nice potential. Not as powerful but plenty. I believe that remington did a very poor marketing campaign with that ugly camm uppers and rifles and the 4 round mags and the 125gr round when in fact it can take a 168grainer and possibly more. The case is very strong and can take nice bullets....


    Reports are of pretty good accuray and DPMS has the 10 rounder single stack magazine, similar (or same, not sure) than the 450 bushmaster but anyway folks say it works flawlessly. Also cheaper than OSSM to buy and to reload and even with the korelokt 150gr much better than the 7.62x39 or 6.8SPC specially past 250yards.

    Last edited: Jan 22, 2011
  15. lilquiz

    lilquiz Well-Known Member

    I understand you concerns. This load set to 2.85 has already been tested and has produced a sub moa. My testing was done with a easymag modified to allow 2.34. I want to test these loads which look fine(no gap or crimp) and have plenty of neck tension. There is no book data on any ossm round. All data states a 2.35 col, which we all know is impossible for this systems standard mags.
  16. 1stmarine

    1stmarine Well-Known Member

    Any progress? I believe the maximum you could run after mag modification and w/o stepping over the o-give was 0.61" ...Makes sense?
    I might be wrong.

    Last edited: Jan 31, 2011
  17. 1stmarine

    1stmarine Well-Known Member

    How are things going?
    here is a picture another fellow WSSM enthusiast who sent me this....
    This is a 6.5mm WSSM with a extremely good long range bullet.
    Too bad we cannot do these things with the AR-15 otherwise long range would have a new meaning with the AR-15.


  18. 1stmarine

    1stmarine Well-Known Member

    In the long quest for long range accuracy out of the WSSM in the AR15 we are done. I am not pursuing any more research for now as we cannot find a solution. So this project is parked for now. Great cases but it is what it is. The round comes out too darn long for the AR-15 to be a good LR round no matter what you do. It might work ok for many folks but not for my purpose though.
  19. sscoyote

    sscoyote Well-Known Member

    Well, looks like i got here a little late. I have a 243 WSSM from a custom builder that doesn't shoot great as well. I've only used the 87 V-Max but groups are not better than MOA with virgin brass. Resized some recently but have to get to the range Wed. to see what i can achieve. Gonna try some 80 Noslers as well. The .3+ BC oughtta' get me to 600 under ideal conditions if i can get ~.75MOA or so. We'll see. My take on the WSSM AR-15 is as a damage control long range coyote system. I need something that will perform as far out as i can get it to.

    There may be an option to get .25" more COAL out of it, if that's what u guys are looking for. I'll check measurements tomorrow after i wake up and post my idea, roughly based on the old DPMS VLD magazine system that i'm using for my 223 AI AR now.
  20. lilquiz

    lilquiz Well-Known Member

    1stmarine I have not researched any more mag conversions. I have been getting such good results with the 175 smk there is no need. However I discovered a slight difference in bullet shape for the nosler 168 ballistic tips may have to modify a mag to give me a 2.3 or 2.35. The easy mags are the easiest to modify. Oly has a new prototype lower and mag which give more col... so we will see.

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