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New upper caliber?

Manoa-FishermanManoa-Fisherman Member Posts: 190 ✭✭✭
edited June 2013 in Ask the Experts
I currently have an older Bushmaster with a 16" barrel in 223. I was thinking about getting another upper in another caliber, but I don't want to have to re-work the lower receiver to us it.

What options do I have in getting a new upper in a new caliber that does not require modifications to my lower receiver? In other words, what "drop-in" options do I have?

Thank you for any comments.

Comments

  • rufe-snowrufe-snow Member Posts: 18,650 ✭✭✭
    edited November -1
    Most obvious choices would either be .22 LR or 300 Whisper/Blackout. There are others available like the com bloc, 7.62 X 39 & 5.45 X 39. You would be much better off with either of the first 2, IMHO.
  • carbine100carbine100 Member Posts: 3,071 ✭✭✭
    edited November -1
    ... also 6.5 Grendel, 6.8 Remington SPC, .50 Beowulf, 5.7X28 FN, .45 ACP, 9mm Luger, .204 Ruger, 10mm Auto, .40 S&W, .243 Winchester Super-Short Magnum come to mind.
  • 62fuelie62fuelie Member Posts: 1,069 ✭✭✭
    edited November -1
    My swap-out is a 6.8 SPC and it just drops on. Also consider .30 AR.
  • rsnyder55rsnyder55 Member Posts: 2,526 ✭✭✭
    edited November -1
  • nononsensenononsense Member Posts: 10,928 ✭✭✭✭
    edited November -1
    Manoa-Fisherman,

    The 6x45 is a superb cartridge and a little different by caliber (6mm) but on the same case (.223) as the original.

    Getting a slightly faster twist will allow for shooting the heavier bullets on deer as well as being an accurate paper puncher.

    Best.
  • MobuckMobuck Member Posts: 14,124 ✭✭✭✭
    edited November -1
    Much depends on whether you plan to reload. The 5.45x39 is the most economical centerfire on the market at this time but some of the ammo is corrosive(not such a big deal just needs prompt & proper cleaning). Next would be the 7.62x39 costwise but both of these Russian military cartridges require specific magazines which are a little harder to find and more expensive.
    If you reload, the 300AAC is a viable alternative since ammo is nearly impossible to find at a reasonable cost. This round uses the same mags and bolt as .223 and is very economical to load. A pound of H110 will load about 350 cases.
    Adding a 22lr upper gives you the opportunity to handle your AR more and allows practice at shorter ranges with less noise. Downside is mags are double the price of .223 mags and unless you have the 22 ammo, you're looking at steep cost there.
    The 6x45mm is a very good wildcat but only an option if you're a skilled handloader. This is the only caliber I've mentioned which I don't own and shoot.
    The 6.8 is probably a good round(I haven't tried it so really don't know)but ammo and mags may be costly and hard to find.
  • beantownshootahbeantownshootah Member Posts: 12,776 ✭✭✭
    edited November -1
    quote:Originally posted by Manoa-Fisherman
    I currently have an older Bushmaster with a 16" barrel in 223. I was thinking about getting another upper in another caliber, but I don't want to have to re-work the lower receiver to us it.

    What options do I have in getting a new upper in a new caliber that does not require modifications to my lower receiver? In other words, what "drop-in" options do I have?

    Thank you for any comments.


    As mentioned, choices are broad. There are a variety of handgun rounds that can be run through an AR-15 with minimal modification, a bunch of rifle rounds based on the .223 case, and a whole bunch of non-.223 rounds.

    The real question is, what do you want to do with this gun?

    IMO, if you're not reloading, you'll want to stick to a common rifle or handgun caliber, both for off-the-shelf availability, as well as commonality with other guns you may own. Being able to share ammo between guns/platforms can be helpful.

    Some of the more platform-specific rounds like 6.8SPC and .300 Whisper, etc are excellent in their own right, but these are not typically rounds you're going to be able to find on the shelves of your local sporting goods store. If you're not reloading, they're probably not practical.

    I'd say probably the best single conversion you can get is a good dedicated .22LR upper. That will give you lots of extra trigger time with this platform at a fraction of the cost of any centerfire cartridge, plus .22LR is pretty useful in its own right.

    Don't know what the ammo situation is like where you are, but FWIW, things are slowly starting to turn around now. Guns that were totally unavailable 6 months ago, are now readily available at close to pre-panic prices. Ammo is starting to open up a little bit.

    Although .22LR is still scarce and expensive, I think things will gradually return to normal there too over the next 12 months.
  • Manoa-FishermanManoa-Fisherman Member Posts: 190 ✭✭✭
    edited November -1
    Thank you all for your comments and suggestions. I was thinking more in line with just a simple alternative to 223, but looking at the cost of uppers, other than 22lr, seem to be outside of what I would consider simple. The price for those uppers appear more than a whole new carbines in some cases, which I would prefer at current prices of the uppers listed on GB.
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