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Old November 12, 2018, 11:26 PM   #1
kymasabe
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Bigger Bore AR's - suggestions?

I have a spare stripped lower layin around and I have a stripped slick side upper coming soon. So, of course I'm starting to think about my next build
I've been a ton of .223/5.56 AR's and I'm thinking maybe I'd like to build a bigger bore rifle. So, since I'm new to this area, I was wondering what could I build that would fit in an AR15 receiver. I don't want to have to buy AR10 stuff, I'd like to use what I have.
First that comes to mind is .300 Blackout, but I'd never run subsonic and suppressed so..what's the point.
Plus...I want bigger. ( I may mention so calibers that require the AR10 receivers, so please bear with me and ignore my ignorance).
Other's I've thought of were .224 Valk and 6.5 Grendal but, I'm not really a long range guy and honestly, I can't afford the $1000 scope and high end barrels and triggers that those long range guns require. I'm more of a 100-200 range guy, possible hog gun, and I want something that has some bark to it. Plus, something I can get ammo for. I'm thinking maybe .450 Bushmaster?? Unless that's an AR10 size, or unless it totally sucks and you all can come up with a suggestion for an alternative. I thought about 6.8 SPC but I hear that's hard to find and on it's way out so...wasn't sure.
What say you all ?
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Old November 13, 2018, 12:03 AM   #2
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.50 Beowulf.

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Old November 13, 2018, 06:18 AM   #3
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I built a couple of 300 Blackout rifles for myself and 4 or five for other guys, all are quite happy with the cartridge and all of us shoot only supersonic. I took a Texas hog that weighed 375+ pounds with mine. I then built a 6.5 Grendel for my buddy, we both shot hogs with it so I made one for myself, it is a good animal rifle and with a $200 Nikon scope it will drive nails near or far. The good thing about these calibers is only a few modified parts are needed. And
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Old November 13, 2018, 07:34 AM   #4
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"I thought about 6.8 SPC but I hear that's hard to find and on it's way out so...wasn't sure."

The 6.8 is only "on it's way out" TO GO HUNTING. ARP can't keep barrels in stock. There's a dozen ammo variations available. It's easy to shoot and whacks critters quite well. I don't consider it a "high volume" blaster so in reality 500 rounds will last a long time. Budget ammo is 60 cents a pop and quality hunting ammo is .80-$1.00.
I think the 6.8 is a better choice than 6.5G as the 6.8 isn't finicky about it's ammo as the 6.5G seems to be.

FWIW
You don't HAVE to shoot the Grendel or Valk "at long range" ALL the time and you darnes sure don't NEED a $1000 scope to use either. In my experience, the Grendel is pretty "doggy" as a "long ranger".
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Old November 13, 2018, 09:05 AM   #5
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Ibmikey and mobuck have me taking a second look at .300 blackout and 6.8spc.
50 Beowulf is out. Too big, not mainstream enough.
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Old November 13, 2018, 09:35 AM   #6
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Bigger Bore AR's - suggestions?

Call up Rudy at Macon Armory... send him your stripped upper, and have a D/I .45 ACP built off it.

He also has a magazine adapter and 20 rounders available to fit the standard magazine well.

Might not be bigger in cartridge length, but 230 grain .45 bullets are pretty large. And they are available everywhere.





Mine... using H&K USC magazines. Can’t wait to move, and get a set of 20s.
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Old November 13, 2018, 11:44 AM   #7
FrankenMauser
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In order of my own preference:
(Sticking with AR-15 cartridges, nothing AR-10/AR308.)

.458 SOCOM*
.375 SOCOM*
.45 Auto
.450 BM
.50 Beowulf


*Anything .458 SOCOM (or based on it) needs to come from a reputable maker. There's a lot of garbage out there that will cause nothing but headaches. Right now, BCA is kicking out some barrels and bolts that are the biggest offenders. Tromix, Rock River, and a couple other places are good to go. Most others... crap shoot, or total waste of money.

6.8 SPC would be good, as would 6.5 Grendel.

I don't think .300 Blk would be a good fit if you're wanting 'bigger bore'. The increased bullet mass smacks things harder than .223/5.56, but there isn't much else going for it if you're not interested in suppressing it. If you want to shoot 110 to 150 gr bullets, 6.8 SPC will do it better (and with bullets better suited to the job).
I've long believed that .300 Blk wasn't much good, considering other options out there, outside of subsonic loads with a suppressor. Now that I own one, my opinion has been reinforced. With a suppressor, it's a fun cartridge. Without a suppressor, it's a waste. Other things will do it better.
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Old November 14, 2018, 08:03 AM   #8
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The 300AAC does fit a niche even unsuppressed/super-sonic. It's more powerful than a 30 carbine and more accurate than a 7.62x39(and doesn't require ANY adjustments to the lower or special magazines).
It has a recoil level that's manageable for anyone who can hold themselves erect. Shoots some very effective bullets. Has enough range to meet the needs of many hunters.
It wouldn't be my first choice for general use. It doesn't kill varmints nearly as well as a .223 and it's bullets are more like to ricochet than the more frangible smaller caliber bullets.
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Old November 14, 2018, 10:13 AM   #9
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6.8 for something with bark and bite for hunting. Not sure why people claim it's hard to find. My local gun shops always has ammo for the 6.8 in stock. I would recommend the 6.5 Grendel too. Both are similar in performance.
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Old November 14, 2018, 02:12 PM   #10
kymasabe
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300 blackout is looking pretty easy to build: I'd want to keep it supersonic for my needs, so 16 inch with 1:8 seems easy to find. I just need to figure out whether pistol or carbine length gas is what I need. I was surprised by the cost of ammo. I (incorrectly) assumed it was around the same price as .223 or 7.62x39.
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Old November 14, 2018, 04:19 PM   #11
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I’ve used both 300 blackout and 6.8 SPC for deer here in SC. Both are good. I limit the .300 to 150 yards for deer, 6.8 for me is about a 250 yard deer round. 6.8 requires a different bolt, mags, muzzle device and barrel. The .300 needs only a barrel and muzzle device. Keep .300 mags and ammo separate from .223/5.56 mags and ammo to prevent catastrophic disassembly of your .223 rifle.

In my area .300 and 6.8 are easily available.
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Old November 14, 2018, 04:27 PM   #12
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I have 5.56, 6.5, .300, and .450 ARs.

Happy with them all for different reasons.

I prefer the pistol bullet .450 to the rifle bullet .458 for my uses (in a short barrel).

Good luck with your decision.
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Old November 14, 2018, 07:25 PM   #13
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I am happy enough with my 6.5PCC and 10mm that the .300BOs are both sold and .450BMs are currently list for sale.
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Old November 14, 2018, 08:35 PM   #14
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I went the 450 route. Recent changes in Iowa law now allows me to hunt with rifles, the 450 fell within the new guidelines. Plus, as a reloader I can use cheap 230 fmj for range use.
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Old November 14, 2018, 10:12 PM   #15
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"I just need to figure out whether pistol or carbine length gas is what I need."

I have carbine length gas systems on all 3 of my 300's (2 x 16" and 1 x 10.5") The 16" slow twist (1-10) w/o muffler runs best with a lightweight carrier and the 10.5" is only used with the muffler and runs well with a standard buffer.
We found the pistol gassed 10.5" gets a bit rambunctious muffled with a standard buffer. Not to the point of breaking parts but brass lands about 2 o'clock.
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Old December 4, 2018, 07:11 AM   #16
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I know two gents who used the .450 Bushmaster in hunts this year. They both said their deer dropped where they stood. Both are very happy with the AR in this caliber.
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Old December 4, 2018, 09:08 PM   #17
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Grendel????

I'n not a hardcore AR guy, but were I building an AR to hunt a little, but more cartridge than the 5.56mm, so that I could take medium game at 200 yds, I'd look hard at the 6.5 Grendel.

The Grendel has a some of a support net, I see the ammo at bulk stores like
Academy, there is even steel case (Wolfe?) available. Howa has chambered the cartridge in their mico action (?) and I recently saw where Ruger has chambered the American Predator rifle in it too. All that seems to indicate the cartridge will have a following into the future

On the build, you don't need to add top end components. I'd hazard a guess that a standard trigger group a good barrel (not junk, not top shelf either) and basic hunting scope (3-9x) should yield sufficient accuracy to 200 yd to satisfy. I'm not sure about reliability, the Grendel gets its punch from a "short fat" type cartridge, but I bet that could be worked out.

Though I stated earlier I'm not really into AR's, I have thought given some thought about an AR carbine in the Grendel as a rough and tumble whitetail rig here in the south where out deer go 150 lbs or so on the avg and ranges tend to be short. Heck, the 7.62x39 and .44 mag have been working ok for me, the Grendel would too.

Finally, factory ammo for the really big bores like the .450 and .50 is expensive, on the surface ( a quick check of Midway prices) it looks like one could shoot the Grendel "off the shelf" for about half the cost of shooting the really big bores.
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Old December 4, 2018, 09:11 PM   #18
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soft

The Grendel would be a peach to shoot, the big bores, not so much.
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Old December 4, 2018, 10:19 PM   #19
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I was always fond of the 35 Remington and the 44 Auto Mag
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Old December 5, 2018, 08:31 PM   #20
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Big boom in an AR 15? 458 socom hands down.
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Old December 5, 2018, 11:34 PM   #21
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Biggest boom available for the AR-15...45VRAP!
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Old December 6, 2018, 12:20 AM   #22
stagpanther
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Quote:
Biggest boom available for the AR-15...45VRAP!
Yup--and brass, ammo and barrels are on sale everywhere.
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Old December 6, 2018, 10:49 PM   #23
TimW77
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Large Bore ARs

"Big boom in an AR 15? 458 socom hands down."

Have to agree, the .458 Socom is the best of the big bore ARs...

For a MEDIUM BORE, the 6.5 Grendel can't be beat!!!

TW
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Old December 7, 2018, 07:04 AM   #24
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Quote:
I started with a .458 and sold it. I had a hell of time reloading for it. No matter what I did, I would randomly get stuck cases. No rhyme or reason. Tried all kinds of lube. A google search showed I wasn't the only one. I liked the round but if couldn't reload it, I wasn't gonna own it. $2 a shot for factory.
What part of the case was getting stuck in the die--and who's die were you using? My experience has been the exact opposite of yours--in fact, when I put my 458 socom together I bought 100 cases from starline for pretty cheap and am still using those 100 cases many reloads later. I'm guessing you were getting the expander sticking in the neck and pulling the rebated rim through the shell plate that didn't fit quite right? Hasn't happened with me with the 458--but that's a pretty typical scenario for stuck cases--or an over-expanded base of the cartridge from a bit of overpressure which can't be "sized-out." I prefer the 458 precisely for it's small shoulder--and the fact that it's one of the only big-bore calibers that has mostly actual rifle bullets made for it. For hunting purposes it probably doesn't make much difference which of the "big 4's" you use, though I still prefer a rifle bullet over a gaping pistol hollow-point in a rifle. If I didn't already have my 458 socom--I would buy Ruger's American predator ranch rifle in 450 B in a heartbeat--might get one anyway eventually, but then that also means investing in new dies, bullets etc. I've driven a 325 gr Accubonds at about 2000 fps with my 458--though the most accurate bullet I've used so far is the 300 gr extreme penetrator which I've shot 1-hole groups with. As impressive as that sounds, because the bullet is so big a 1-holer can still be over 1 MOA.
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Old December 7, 2018, 07:42 AM   #25
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The 223/5.56 does everything I want to do with an AR. But if I were inclined to use another caliber 6.5 Grendel is the only other one that interests me. The 45 caliber options just recoil more and limit usable range. The 6.5 or 6.8 will kill anything the 45 caliber options will kill and do it at much longer range. With a lot less recoil and cost.
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