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Lightweight 6.8 SPC II AR

Discussion in 'Rifle Country' started by gbw, Dec 4, 2019 at 6:46 PM.

  1. gbw

    gbw Member

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    I have a standard Anderson lower and a Wilson 27 oz. stainless 6.8 barrel that I'd like to build into a lightweight AR style hunting rifle.

    I'm not an AR guru, so if anyone has ideas I'd love to have them.

    Thanks,

    PS - please don't go into the 6.5 Grendel v. 6.8 SPC arguments here. Too late, I have the barrel.
     
  2. <*(((><
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    <*(((>< Luke

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    First of all great choice in caliber for a lightweight hunter and I've heard good things about Wilson 6.8 SPC II barrels, they are one that has a good reputation.

    What barrel length?
    What gas length?
    Twist Rate?
    What ideas are you looking for?


    What I would do is:

    1. LaRue MBT-2S trigger
    2. A2 fixed stock
    3. SLR Rifleworks Adjustable gas block
    4. JP Enterprises Captured buffer system
    5. CODA carbon fiber handguard; or Midwest Industries rail if wanting a cheaper option
    6. Threaded muzzle
    7. LWRC bolt
    8. Leupold 1.25-4x20mm VXR Patrol
    9. Aero Precision Lightweight 1-piece mount
    10. Get some Sellier & Bellot ammo for the brass and components and away you go.
     
    Last edited: Dec 7, 2019 at 9:40 AM
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  3. WestKentucky

    WestKentucky Member

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    Pistol tube and a brace are lighter than even a carbine stock setup.
     
  4. Varminterror

    Varminterror Member

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    @gbw - do you really want a “lightweight” build, or are you really just looking for something “not heavy”? There’s a big difference in building a qualifying ultralight AR and simply building something which doesn’t make you feel like your arms are going to fall off after a day of still hunting whitetails.
     
  5. marksman13

    marksman13 Member

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    I put this one together a couple years ago mostly for hunting pigs. I’ll have to see if I can find the parts list, but it is fairly light weight. I had the Wilson Combat Barrel fluted to shave weight. Aero slick side upper because a foward assist adds more weight than function. Midwest Industries 15” SS rail and Geissele trigger and Nikon Monarch 1-4x20 scope round out the parts I can remember off the top of my head. It’s right at nine pounds with a full 25 round mag and Silencerco Harvester suppressor. Never put it on the scale without the can and full mag, but I’m gonna guess it’s around 7 lbs and it is a friggin shooter too. D3751CC2-431D-434A-9A4A-5E7DCAB12B21.jpeg D4E83627-380B-4063-85BE-4361F4B4A082.png
     
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  6. <*(((><
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    <*(((>< Luke

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    @marksman13 did you do the camo job? That is a sweet carbine! I have a few of the Midwest Industries rails like yours but without the pictinney in the center of the top of the rail just on the muzzle end for a few inches and just in front of the upper receiver. They are lightweight as far as aluminum rails goes.
     
  7. mshootnit

    mshootnit Member

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    I used the Midwest Industries free float handguard, A2 Hider. Lo profile gas block pretty straightforward, and light. My barrel is the Bison 18" light contour (recon?) YHM clamp-on style non adjustable block. Geissele trigger. No swipes, perfect function so far, no issues. KISS applies for me. Check out Surplus Ammo and Arms for some good parts, I think I got my upper receiver, carrier and some stuff from them which all seems to be very high quality and fair priced. https://www.surplusammo.com/categories/ar-15-parts/bolt-carrier-groups.html
    Also I got my bolt from Bison already headspaced to the barrel so I did not have to worry about that.
    IMG_20190921_233051719.jpg
     
    Last edited: Dec 5, 2019 at 10:03 AM
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  8. <*(((><
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    <*(((>< Luke

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    What all will you be using it to hunt?
     
  9. <*(((><
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    <*(((>< Luke

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    Just so you know if you are reloading get yourself some of the newer style (they are old tech now) ASC magazines, as they allow longer loading than other 6.8 SPC II magazines, it allows you to get more powder in there without compressing the load as much. Don't know if you are a reloader or not, but the COAL makes a different on squeezing performance out of the 6.8 SPC II.

    ASC%2015%20round%20-%202.315in%20COAL%20%28resized%29.jpg
     
  10. <*(((><
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    <*(((>< Luke

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    303 hunter likes this.
  11. marksman13

    marksman13 Member

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    I did not do the camo job. A buddy of mine owns Rayzor’s Edge Tactical in Joplin, MO and he did the assembly and the Cerakote work based on the colors I chose. It’s a spin on Multi-Cam for sure, but a little darker base.
     
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  12. z7

    z7 Member

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    I’d say use an aero enhanced upper, not terribly heavy but the extra material and the barrel but attachment add rigidity and go further to free float the barrel and enhance accuracy potential

    next, get a nice trigger, trigger tech, geissele, etc, something “pricey” that feels good to you, I like a 2 stage in an AR

    for a light weight scope, considers Trijicon accupoint or accupower, (accupoint 3-9 weighs. 15oz)

    then try to wear out the barrel and have fun
     
  13. mshootnit

    mshootnit Member

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    You can save quite a bit of weight also by avoiding steel rings or large scopes. Aero precision makes a very light and inexpensive scope mount.
    Leupold scopes are very lightweight as well. Even a 2-7X scope will have plenty of magnification for the 6.8.
    Handguard weight can be cut down as well. Some of the tubes are heavier than others. You can also choose your float tube length. For example if weight is the main concern you could do a 9-10.5" tube on a midlength gas barrel rather than a 12-15" tube.
    Keeping in mind that a certain amount of length is needed if you want to completely cover the gas block.
    The newer narrow tubes are lighter but you need to be sure your gas block will clear the tube if you are covering it up.
    Also some gas blocks are heavier than others. The steel blocks with a tall rail on top are heavy chunks sitting out there. The low profile steel blocks can be much lighter.
    Your buffer itself can vary by a couple Oz. depending on what buffer weight you choose. Mine is either H or H2.
    An A2 flash hider is much lighter than some of the bigger brakes, if weight is the issue. A2 hiders do nothing as a brake, but do tame a little muzzle flip AND they are a great muzzle protector if you are throwing that rifle into the truck barrel down.
    I don't mess with low mass carriers etc. but some weight could be saved AR vs. M16 carrier I think.
    If you check weight on each component as you go the weight savings add up.
     
  14. <*(((><
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    <*(((>< Luke

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    Guess one of us should have thrown a 6.5 Grendel vs 6.8 SPC argument in there to keep the OP interested in his thread
     
  15. gbw

    gbw Member

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    Sorry guys, I'm interested, had to be away. I appreciate all the helpful comments, I've a lot to think about.

    The barrel is a Wilson Recon, 16", 1/11" twist, stainless. The lower is Anderson. and I've an Anderson upper, stripped, ordered. I have a very good Geissle trigger for it.

    For hunting, deer and hogs, unlikely to see anything larger.

    I'm interested in keeping it as light as reasonably possible. The barrel weighs a shade over 25 oz., and of course the lower/upper weigh very little.

    I don't have a BCG yet, nor gas block / tube, nut, stock, handguard, pistol grip, buffer and buffer tube & spring, or scope and mounts, upper & lower small parts. I'd like at least 4x, which should be enough - nobody I know, including me, has any business taking a shot at an animal over about 350-400 yds. regardless of the rifle.

    I'd like to use an adjustable gas block just to keep options available. Is a Toolcraft BCG good? Probably won't bother with flash hider and just put a thread protector on it.

    I'm interested in weight as I have a standard Colt M4 with a Leopold VX-R 1.25-4x 30mm scope, and it weighs nearly 8 lbs. with empty mag. If possible I'd like to stay under this as much as I can.

    Thanks again for all the interest and help! I'll post photos when it's done.
     
  16. <*(((><
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    <*(((>< Luke

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    I'll have to weigh my 20" 6.8 SPC when I get home.

    The barrel on it weighs 2.6 lbs. So right there you are shaving 1lb. off of my weight. I think with what I proposed above in my first post with the weight of your barrel you will be around the same as your M4. Now if you went with a light weight buttstock, a short light weight handguard you might be down in the 7.25lb. range.
     
  17. gbw

    gbw Member

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    I do reload and I'll get a couple of those mags! I have 4 of the C-somethingorother 10 rd. mags on order from Optics Planet for $52 shipped.

    For those interested in costs, the barrel was $220 delivered, upper $54 and lower were $60 each approx. I'm sure I could have shopped hard to get slightly lower prices but I'm lazy.

    Thanks again everyone, I'll be very interested to see the 18" weight. I could not find a lightweight 18" barrel or I'd have considered it. But from what I've read the ballistic difference is slight.
     
  18. <*(((><
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    <*(((>< Luke

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    6.8SPC does very well on shorter barrels so I'm not gaining too much from my 20" over your 16".
     
  19. mshootnit

    mshootnit Member

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    I think with that barrel and any sort of due diligence on your part, you will end up with a nice light rifle. Lots of light/thin tubes now just be sure they fit over or behind your gas block.
     
  20. Gtscotty

    Gtscotty Member

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    I was going for something similar, when I recently built this in 6.5 Grendel.

    IMG_20191111_100848485~01.jpg

    Parts list is:

    -PSA complete CTR lower
    -Aero M4E1 threaded upper receiver
    -Aero Atlas S-One handguard
    -Wilson Combat 16" Recon Tactical barrel
    -Superlative Arms Adjustable gas block
    -LaRue MBT-2S straight bow trigger

    It's not an ultralight, but it's fairly light and has been shooting pretty well during load development.

    Things I really like thus far:

    - The La Rue trigger. I know I was late to this band wagon, but I'm really impressed with this trigger for $87.

    -Superlative Arms adjustable gas block. This carbine will almost always be suppressed, but I would like for it to run unsuppressed as well. 7 rotations out on the SA adjustment puts me in bleed off mode, it sounds great at the ear and isn't gassy suppressed, but still cycles and locks back with no can. I think I'm going to put these blocks on some of my other ARs as well.

    -Atlas S-One handguard. Lightweight and very compact in the hand while still clearing the adjustable gas block. I think this handguard will lend itself well to quick offhand shooting.

    Things I might change:

    - CTR stock. Really the only thing I'm not digging. I thought the dual latch system would make this stock a little more stable, but even when locked it has some play. It will probably be fine for hunting, but when doing load workup from a bench it's not great. I may keep it anyway because this is not a bench gun, and I'm not sure I can find anything better that's as light.

    Right now I'm running an old Burris P.E.P.R cantilever mount I had laying around, but I like Aero's Ultralight cantilever mounts and I'll be getting another one for this rifle to cut about 5oz.
     
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  21. mshootnit

    mshootnit Member

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    The Bison 18" is pretty light, its just a straight tube, sporter profile. I am pleased. It is actually an ER Shaw barrel.
    For this build I also ordered the chrome carrier from Bison, I think it is a Young Mfg. carrier, it is really sharp looking.
    With my builds I stick to basic qualityparts, not a lot of trick, over complicated, or commercial "tapco spec" stuff. That is why I went with the parts I did.
    A fellow I work with and barely tolerate just built a 6.5. Being the meticulous picky type he bought every tricked out part he could find, captive silent buffer, etc.
    Mine cycles perfect, brass is perfect, and the only thing I ever adjust is my britches.
    He is getting swipes, and stretched brass that looks like hell. Reasearch indicates it is a timingnissue due to pressure curve of the ammo he is using. I am running the same brand (diff caliber) no problem. It is actually a good thing he bought the adjustable block so he can try to make it right.
     
  22. Varminterror

    Varminterror Member

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    Given the confirmation you’re not trying to go ultralight, but rather simply wanting a rifle without excessive weight, then you’re really already there. The barrel is the single most influential piece of the AR puzzle. Barrels can move the needle by pounds, while everything else only moves inches.

    A few more easy ounces can be bought by using an adjustable gas block, a semiauto carrier, and a carbine buffer, but again, these are only a couple of ounces. Personally, with a 6.8, I run full auto carriers and H2 buffers to slow down the reciprocating mass, and I ignore the slight increase on the scale.

    The rest is pretty straight forward. Avoid a quad rail with a bunch of covers, and only use a rail long enough to cover your gas block. The Midwest G3 ultralight and Aero Atlas One mentioned here already are great handguards, but can limit your gas block options. I haven’t used a Nordic tube in a few years for a build, but they’re a nice and light full diameter tube. Use a normal carbine type stock, avoiding something overweight like the ACS, PRS, or UBR. The Aero Ultralight and Warne optic mounts are much lighter than the big and bulky Burris PEPR Mount. None of these choices are spending extra money to cut weight, but all of them are avoiding choices which add little bits of unnecessary fat.

    Beyond all of that, the last thing is to avoid unnecessary bolt ons. No angled foregrip, no back-up iron sights, no 6” sunshade, no emergency fishing kit in the grip, no grip plugs or palm rests, no flashlights on a day rifle, maybe even skip the bipod and mount, etc. Adding anything is adding weight, so if it’s not application critical, or even application relevant, think hard about whether you want to carry its weight.
     
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  23. <*(((><
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    <*(((>< Luke

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    Agreed. Any more lightweight than what was suggested you get the bonus of it being lightweight and expensive.

    no fishing kit...say it ain’t so!
     
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  24. mshootnit

    mshootnit Member

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    Link? (if you don't mind)
     
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  25. gbw

    gbw Member

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    Gun Mag Warehouse has 5rd and 25rd mags in stock, not out of line price wise.

    How long a handguard for this mid-length gas ported barrel?

    Are Toolcraft BCGs ok - I see them for about $90?

    Varminterror - yes, I thought as much but it's good to have it confirmed.

    Gtscotty, very nice - and just what I had in mind, it looks like you can get very near 7 lbs. with scope and mount. Is the PEPR v. Aero LT mount difference really 5 oz.? seems a big difference.
     
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