ar-15 cal.options?

Discussion in 'AR15/10 Rifles' started by beakus33, Feb 25, 2012.

  1. beakus33

    beakus33 Well-Known Member

    Feb 7, 2012
    i have just built up a ar in 5.56/.223, is there any other cal. options i can do with this lower,with just a bolt carrier/barrel change? or is one better building seperate guns all together (never hurts to have more guns,just harder to hide from the misses).
  2. threejones

    threejones Well-Known Member

    Oct 15, 2010
    Their's few out there that just need barrel/bolt and mag changes The 6.8SPC was made to do just that while adding more downrange punch than the 556. 300whisper and blackout are also taylored to work with in the AR platform, as well as a bunch of others that have been necked up or down to fit. What use are you looking for from this gun?

  3. NomadPilot

    NomadPilot Well-Known Member

    Aug 28, 2009
    Stolen from the interwebs:

    AR-15, without bolt modification
    .17 Remington
    .20 Tactical
    .20 Practical
    .20 Vartag
    .204 Ruger
    .221 Fireball
    .222 Remington
    .222 Remington Magnum
    .223 Remington (5.56x45mm)
    .223 Remington Ackley Improved
    6mm TCU
    6mm Whisper
    6.5mm Whisper
    7mm Whisper
    7mm TCU
    .300 Whisper (.300/221, .300 Fireball)
    .338 Whisper

    AR-15, with bolt modification
    223 WSSM
    5.45x39mm (.21 Genghis)
    243 WSSM
    6mm PPC
    6mm WOA
    6mm BR Remington
    6mm Hagar
    6.5mm PPC
    6.5 WSSM
    6.5 WOA
    6.5mm Grendel
    25 WSSM
    6.8x43mm SPC
    .30 Herrett Rimless Tactical (6.8x43mm case trimmed to 41mm and necked up to .308; the 6.8mm version of the .300 Whisper)
    .30 RAR
    300 OSSM
    .357 Auto
    .35 Gremlin (necked up 6.5 Grendel to 358)
    .358 WSSM (various names, but all are some form of a WSSM necked up to 35 caliber, some are shortened to make them big game legal in Indiana)
    .458 SOCOM
    .50 Action Express
    .50 Beowulf

    AR-15 using a simple blowback operation
    .17 HMR
    .22 LR
    .22 WMR
    30 Carbine
    357 Sig
    400 Cor-Bon
    41 Action Express
    10mm Auto
    45 GAP
    45 Super
    45 Win Mag

    And then some...
  4. beakus33

    beakus33 Well-Known Member

    Feb 7, 2012
    i built it beacuse i have wanted one for about 15 yrs but never wanted to drop the cash, then this one came along cheep so i splurged. i figure it a good shooter gun one can afford but i think it could use a little more punch. so i was thinking about a 7.62x39(still pretty cheep ammo)i dont know about the 6.8spc or "blackout". but i dont want to go to the point it gets to pricey to shoot.
  5. kc0pph

    kc0pph Well-Known Member

    Aug 6, 2011
    458 SOCOM

    only one worth switching to :)
  6. brentc

    brentc Well-Known Member

    Apr 3, 2009
    For inexpensive shooting, the 7.62x39 is pretty economical. For all around performance in a standard AR, the 6.5 Grendel is tough to beat.
  7. threejones

    threejones Well-Known Member

    Oct 15, 2010
    If you hand load it doesn't really matter as they're all fairly cheap to load. If you're buying ammo off the shelf stick with the 223 or 762. Be careful with the 762, alot of the cheaper ball ammo builds up crud in the AR shockingly fast, and can be pretty corrosive as well.
  8. Kevin Thomas

    Kevin Thomas Well-Known Member

    Feb 16, 2009
    Some other good options mentioned here, but I'd suggest avoiding the 7.62x39 due to reliability problems. Frankly, I've never seen one of these that would function reliably, which is kind of ironic since it's probably one of the most reliable cartridges ever designed for automatics, and the AR is one of the most reliable autoloaders ever developed. They just don't play well together, due to the geometry of the cartridge and the mag design of the AR.

    The real question here, is what do you want to use this rifle for? That question alone should steer you into the right choice.
  9. LouBoyd

    LouBoyd Well-Known Member

    Oct 15, 2007
    At least one other cartridge which feeds though the AR-15 lower magazine is 2-1/2" 410 shotgun. An 18" smoothbore semi-auto upper is imported from Safir Arms in Turkey.

    There are several uppers in which ammo does not feed though the lower. One is the AR-57 upper. It uses a 50 round FN magazine mounted above the barrel and shoots 5.7x28 FN ammo. It's available in pistol/SBR or carbine barrel length. It uses the lower mag well to drop or catch spent brass.

    There are also several makers of large caliber single shot uppers which use the AR-15 lower. Those are available in 50 BMG, 416 Barrett, 338 Lapua, and other calibers.

    There's even the PSE TAC crossbow upper for an AR-15 lower.
  10. beakus33

    beakus33 Well-Known Member

    Feb 7, 2012
    kevin, theres no real reason other than " just cuz" or i wish the 223 had a little more thump. and i figure i better spend it before the wife does!I love the ar platform,if you set and really look at it the design they were ingeanious in the way its simple but effective,adaptive,reliable,ease to assy. and repair or replace. the best way i can explane it to people is,its like building a drag car out of a JEGS catalog.
  11. J E Custom

    J E Custom Well-Known Member

    Jul 29, 2004
    Lou is right . There are so many that it is hard sometimes to decide.

    If you want a middle of the road caliber the 6.8 might be a good choice and another good one
    that has not been mentioned is the 450 Bushmaster. It uses a 250 grain bullet @ 2200 ft/sec
    and is death on hogs. Bushmaster makes the upper (It is specail built for this cartrige) and
    comes in 2 barrel lengths. I also have the Tac 15 for my AR lower. all the uppers fit, and function
    great on my Rock River lower and are easy to change out.

    The only modification I made to the lower was an aftermarket trigger.

    Lots of choices. look at as many cartriges as you can and decide based on need and usage.

    good hunting

  12. Kevin Thomas

    Kevin Thomas Well-Known Member

    Feb 16, 2009

    Fair enough, and a perfectly valid reason. However, it's the one answer/reason that doesn't automatically resolve the caliber choice question. Got a 300 AAC Blackout going together myself right now, for no other reason than it's a neat little concept and I wanna play with it. Just ordered a bunch of other uppers and lowers that I suspect are eventually going to turn into 6.5 Grendels or LBCs, and possibly a 6.8 SPC. But you're right; they're tinker toys for bigger kids, and they can be done up in ways only limited by the imagination.

    Have at it!
  13. durak

    durak Well-Known Member

    May 29, 2011
    I love my 6.8 SPC - I have killed many Mule deer, elk, black bear, and coyotes with mine over the past 4 years. My two oldest kids have also killed their first animals with it. Overall, I consider it one of the best AR platform improvements in the history of AR's. My only wish is that I could have carried it in Afghanistan or Iraq!gun)
  14. rdsii64

    rdsii64 Well-Known Member

    Dec 11, 2008
    When it comes to the AR15 the sky is truly the limit. There are so many directions you can go it will give you a headache. You did mention that you wanted more punch. contrary to popular thought process on the web, the .223 has a lot more punch than people think. It's certainly no replacement for a larger bore rifle but you would be surprised what you can do with one if you use the right bullet and stay within its balistic limitations. I personally am a 6mm fan. When I have the money on hand I want to build a 6mm turbo 40 upper.

    Now that I have come down off my soap box, exactly what are you going to do with the secondary upper?