Ar15. What caliber would you choose?

[Dildobaggins]

So I have 1 stripped ar15 lower sitting in my safe. Having it not on somthing is keeping me up at night . I already have a 5.56 that I use to plink and quick acquisition of targets
I have a 6.5 grendel for varmint
22lr for plinking and limb rats
And ar ar10 for deer

I want to build somthing with this, but ive lost my creativity. If you could build any gun off of an ar15 lower what would it be and why? Also, for this hypothetical lets say there is not a pandemic, and ammo and everything else is readily available. Thanks!

 

[SBRSarge]

What do you wanna do with it.

Midwest deer hunting? Maybe 350 Legend or 450 Bushy

Medium range target or varmint hunting? Maybe a target 5.56

Longer range target or antelope hunting? Maybe 6mm ARC

I feel your pain. I have two lowers and am undecided myself.

 

[loveha]

Got a can yet? 300BLK? Otherwise, maybe the new 6 ARC.

 

[Dildobaggins]

Got a can yet? 300BLK? Otherwise, maybe the new 6 ARC.

I'm in NY, even mentioning a suppressor is like 25 to life in prison.

 

[loveha]

I'm in NY, even mentioning a suppressor is like 25 to life in prison.

Good thing the government can't read thoughts. If I had a lower doing nothing, I would do 6 ARC then.

 

[acudaowner]

Id either stay 223/556 if you already have everything else covered why change what's not broken unless you have a specific need for another round .

 

[charnicus]

Do a sick recceish / SPRish rifle and see what you can squeeze from it. Might be surprised. Aside from now, there is typically some good factory ammo in abundance and you’re likely to have a pretty trouble free gun. If you wanna wildcat check out some of Padom’s threads or where he heavily treads. There are a lot of neat ones out there that are less mainstream.

 

[Navy Gunner]

Personally,
my next AR build will be a 50 Beowulf - Heavy hitter <300 yards Just because
Previous builds for your additional consideration:
5.56 A2 w/carry handle and open sights
6.5 Grendel w/ 16” heavy barrel and red dot (my ranch gun)
6.5 Grendel side charge w/ 24“ heavy barrel (qualified 1,000 yards with this one)
224 Valkyrie w/ 24” heavy barrel 6.5 twist for long range steel and varmints

 

[Jcmar15]

I’ve messed around with a lot of different calibers in AR’s and always end up back at 223/556. It’s so versatile and with the wide range of loads out there you can do about anything with it. That being said I do have a .300 BO pistol and a 18” 224 V that I can’t bring myself to get rid of, but both have very specific purposes.

 

[GTOJOSH]

With the current price of ammo, a 50bmg upper is edging to be a nice plinker concept...

 

[GUNNER10]

If you are a fan of shooting critters, I think that a 300blk would be pretty fun

 

[loveha]

If you are a fan of shooting critters, I think that a 300blk would be pretty fun

Without a can, I feel the Grendel fills the same roll. Which he says he uses for varmints already.

 

[Bullspotter]

I have grown into my 300 BO, its pretty much my go to now, shooting 125 speer TNT with H110, 16 inch with no can. Cost a bit more to reload for with the .308 bullets, but their is a huge assortment of them that seem at times in the last 8 months to be more available. 223 brass is everywhere so you dont need to hunt down brass at some crazy price.

 

[XLR308]

Unless you just want to try one of the new latest and greatest rounds we all cant live without i would do another 556.
Or a 12" 6.8SPC for a compact efficient thumper.

 

[Dildobaggins]

Personally,
my next AR build will be a 50 Beowulf - Heavy hitter <300 yards Just because
Previous builds for your additional consideration:
5.56 A2 w/carry handle and open sights
6.5 Grendel w/ 16” heavy barrel and red dot (my ranch gun)
6.5 Grendel side charge w/ 24“ heavy barrel (qualified 1,000 yards with this one)
224 Valkyrie w/ 24” heavy barrel 6.5 twist for long range steel and varmints

50 Beowulf has intrested me. My 6.5 grendel has a criterion 22in Hbar

 

[squib]

I'm in NY, even mentioning a suppressor is like 25 to life in prison.

Hello neighbor. 9mm other?
Cumho hates others

 

[TRPrecision]

When I got bored with the normal AR calibers, I built a 458 SOCOM. I love it, sort of like shooting a 45-70 in a MSR. If you can't have a suppressor I see no valid reason for a 300BO. 224 Valkyrie can be a great shooter, but has likely been outshined by 6mm ARC. A dedicated 9mm SBR is pretty sweet as well. What do you want it to do? The choices are vast.

 

[tuckybill]

Do like Bullspotter. Long barreled 300 blackout. You can put a flashcan on it to help a tiny bit with blast. Set it up for sub sonics. Loads of fun....if ammo was available. Do a long range in .223. Think precision. 20+inch barrel. Cut rifled. Good trigger. <----good for SHTF too. Shoot tiny groups at the range with target grade ammo....if it was available.

 

[Dildobaggins]

Hello neighbor. 9mm other?
Cumho hates others

Hahaha hey! I have a JR carbine in 9mm that I'm trying to get rid of. Blowback system. Most reliable firearm ive ever owned, I just dont ever shoot it, and now its expensive as hell to shoot.

 

[Dildobaggins]

Do like Bullspotter. Long barreled 300 blackout. You can put a flashcan on it to help a tiny bit with blast. Set it up for sub sonics. Loads of fun....if ammo was available. Do a long range in .223. Think precision. 20+inch barrel. Cut rifled. Good trigger. <----good for SHTF too. Shoot tiny groups at the range with target grade ammo....if it was available.

I like that idea too!

 

[CrabsandFootball]

If you arent going short barrel suppressed the 300blk which is really just rebranded 300 whisper is a solution looking for a problem. Its also a great way to blow up your gun by switching mags becuase they are identical. This happens more than most know.

350 legend and .450 bushmaster if you want to hunt up to bear /close range elk or are in a strait wall state.

6.5G or 6ARC if you want to push longer ranges and also great for hunting.

.50 and 458S are becoming obsolete with cheap plentifull 350 and 450. 6.8 lost the battle to 6.5 and .224V is dying a quick death.

Or dont build anything...now is the worst time. Buy 10 more lowers and stash them away.

 

[Dildobaggins]

If you arent going short barrel suppressed the 300blk which is really just rebranded 300 whisper is a solution looking for a problem. Its also a great way to blow up your gun by switching mags becuase they are identical. This happens more than most know.

350 legend and .450 bushmaster if you want to hunt up to bear /close range elk or are in a strait wall state.

6.5G or 6ARC if you want to push longer ranges and also great for hunting.

.50 and 458S are becoming obsolete with cheap plentifull 350 and 450. 6.8 lost the battle to 6.5 and .224V is dying a quick death.

Or dont build anything...now is the worst time. Buy 10 more lowers and stash them away.

Correct me if I'm wrong. but I believe parts of the military are switching to the 6.8 they want better range with more knockdown power.

 

[Romeo458]

45acp, you're welcome

 

[RTV]

Correct me if I'm wrong. but I believe parts of the military are switching to the 6.8 they want better range with more knockdown power.

the 6.8 in the NGSW program is completely different than anything on the market right now and is designed to be fired at pressures higher than other commercial loadings so i wouldnt count on making it work with a barrel/bolt swap anytime soon.

 

[Lazyfaire]

Good thing the government can't read thoughts. If I had a lower doing nothing, I would do 6 ARC then.

I had a Barrett 300BO that i turned into a 6mm ARC. Takes a barrel change, a bolt swap and different mags. Put An ARCA rail and bipod to it. Great shooter. I shoot some long range so am looking to get it out for distance. Any AR-15 platform can be modified.

 

[TonyTheTiger]

@Imthatguywithquestions build a race gun in 223. That's a rabbit hole that'll keep you busy a long time.

 

[2aBaC̶a̶]

Valkarie or 6arc.

 

[Billiam1211]

Go down the clone rabbit hole. I’m building a M16A4 (sort of) clone. I won a lower in a raffle and it’s been sitting around. I didn’t want a new set of dies, bullets, powders, etc to mess around with and 1 more rifle that needs optics so I decided to go retro. Only difference is I’ll be using a BCM free float quad rail instead of the Knights RAS. Close enough I s’pose

 

[Odysseus1911]

I have grown into my 300 BO, its pretty much my go to now, shooting 125 speer TNT with H110, 16 inch with no can. Cost a bit more to reload for with the .308 bullets, but their is a huge assortment of them that seem at times in the last 8 months to be more available. 223 brass is everywhere so you dont need to hunt down brass at some crazy price.

125 Speer TNT with H110 here, too.

OP, given everything you already have, I'd recommend
Option 1) move to a better state, buy a suppressor, and do 300blk, or
Option 2) 458 SOCOM

 

[Sidewinder66]

What do you wanna do with it.

Midwest deer hunting? Maybe 350 Legend or 450 Bushy

Medium range target or varmint hunting? Maybe a target 5.56

Longer range target or antelope hunting? Maybe 6mm ARC

I feel your pain. I have two lowers and am undecided myself.

What's your thoughts on .458 socom?

 

[SBRSarge]

The 458 SOCOM is a bruiser of a round. I’ve never given it much though since I’m in a straight-walled rifle cartridge only area for deer hunting.

But if you wish to hunt bigger stuff with an AR 15, and can do a bottle necked cartridge, it’d get the job done within its range limitations. I think it might be a bit more destructive than necessary for deer size game with too much meat damage for my taste.

How does the SOCOM compare to the 450 Bushmaster? I think they’re kind of close and the Bushy has more factory ammo available. And is straight walled if that is a concern.

 

[MarinePMI]

@Imthatguywithquestions build a race gun in 223. That's a rabbit hole that'll keep you busy a long time.

This^^^^

Building, and more importantly, tuning, a race gun, can occupy a lot of time, and yield a gun that is a dream and pleasure to shoot.

 

[TonyTheTiger]

Building, and more importantly, tuning, a race gun, can occupy a lot of time, and yield a gun that is a dream and pleasure to shoot.

Yup. Plus you'll learn a lot about how the system works, and doesn't work, because half the fun is pushing it outside of the normal operational window to see exactly where the limits are.

 

[LuvDog]

SBR it and go with 300BO

 

[Constructor]

For long range the 6mm ARC or 22 cal Grendel has everything else beat in an AR15.
For hunting the 6.8 is a good choice.
No can, no 300.
Big bore350 or 458.

The 6.8 military is a 308 sized cartridge ...270-08 but runs at 80000psi so highly unlikely to find it's way into an AR10 any time soon.

 

[Blutroop]

I'm in NY, even mentioning a suppressor is like 25 to life in prison.

Trade that lower for some land in a free state while you still can.

 

[MarinePMI]

For long range the 6mm ARC or 22 cal Grendel has everything else beat in an AR15.
For hunting the 6.8 is a good choice.
No can, no 300.
Big bore350 or 458.

The 6.8 military is a 308 sized cartridge ...270-08 but runs at 80000psi so highly unlikely to find it's way into an AR10 any time soon.

You understand that a "22 Grendel" is just a 22PPC by another name, right?

 

[Jsp556]

A precision oriented, 16” or 18” 5.56 if I didn’t have one.

 

[ScarlettRed]

Right now, I would do a 224 valkyrie or 350 legend. The ammo is in stock everywhere I go. 6.8 spc is a great round also. I'm half tempted to build one of the two mentioned just for the ammo availability.

 

[Dildobaggins]

Trade that lower for some land in a free state while you still can.

Ive been talking about leaving this state for years. Whole family is here. I cant leave them behind. So I guess I'll just remain a prisoner.

 

[cjs88]

Ive been talking about leaving this state for years. Whole family is here. I cant leave them behind. So I guess I'll just remain a prisoner.

Who needs family?

 

[Ndbowhunter]

It’s hard to look past what a 77gr tmk can do with leverevolution powder in an 18-21” barrel when building ar15 platform.

Before this last summer the 6arc was the direction worth taking in terms of building Something that can sling the monster 108gr eld-m at a meaningful velocity and still maintain a pretty ez logistics chain.

If you need even need that increase in terminal performance. The 77gr has dumped a few truckloads of Wyoming and sodak critters for me and my mates. Don’t overlook what it can do on flesh down to about 1900fps. Expect bang flops 10 yards beyond muzzle to out past 350.. expect 270win with 130’s kind of wound channels down to that 1900 mark.

But staring at it basically February 2021.. unless you can secure a significant amount of components (ammo or brass/primers/powder) mags, spare bolts and the like i’d Rather build redundancy and some capabilities. Rather then stretching resources ona new cartridge.

.02, ymmv

Man the local shop had 25 boxes of 105gr hornady black a few weeks ago. So tempting.

 

[Blutroop]

Ive been talking about leaving this state for years. Whole family is here. I cant leave them behind. So I guess I'll just remain a prisoner.

Stay alert. Your not a prisoner yet per say.. more like behind enemy lines.

In that case I’d lean towards a 458 socom pistol with a 12” threaded barrel for room denial or something like 6.8 cause once you got a few 6.8 bolts you can do 224 valk or di 10mm

 

[Ndbowhunter]

77gr tmk bang flops mule deer at a 2775 launch at 250 yards

It ain’t gonna suck out of an 11.5” at room distance if ur feeding it factory black hills.

 

[RobbW]

I’d vote for a 300 BO. For subs and supers...

Robb

 

[drewthebrave]

Since you have the mid-to-long range capabilities covered with Grendel, I'm not sure 6mm ARC, .224 Valk or 6.8 SPC give you enough performance difference to justify the extra upper & caliber. The benefit of the doubt might go to 6mm ARC since the Bolt & Magazines are the same as your 6.5 Grendel.

I'd probably recommend another 5.56 build that does something your current one doesn't. For example, I have an 18" Mk12, and an 11.5" pistol with red dot -- so I built a 14.5" Recce style upper with 1-4x to split the difference. I'm guessing the pistol options are limited in NY, but you could do a superlight 3-gun build, a classic A2-style build with carry handle, or even a heavy-barreled precision 20"+ for some low-recoil long-range fun. Maybe go for a Gucci high-end build, since all the cheap stuff has crept up in price -- but the high end gear has stayed more or less the same, assuming it's in stock.

.300BLK seems like a great option, but since I can't legally own a suppressor in CA I decided to pass on it. The big bore calibers seem fun, but I've always thought a traditional lever action would be better suited for that.

 

[Constructor]

You understand that a "22 Grendel" is just a 22PPC by another name, right?

You understand that is not correct right? The 22 Grendel has a longer body and more powder volume. The length to the shoulder of a PPC is 1.075", the length on the Grendel cats is 1.150". There are several cats based on the Grendel case. 224 AR, 224LBC, 22 Predator and 22 Grendel. I have made a few hundred barrels in 224 Predator and get calls from guys all the time who have listened to guys like you and tried to use 22 PPC dies to size brass for the 22 Grendel by all other names. It does NOT work.

 

[Ndbowhunter]

You understand that is not correct right? The 22 Grendel has a longer body and more powder volume. The length to the shoulder of a PPC is 1.075", the length on the Grendel cats is 1.150". There are several cats based on the Grendel case. 224 AR, 224LBC, 22 Predator and 22 Grendel. I have made a few hundred barrels in 224 Predator and get calls from guys all the time who have listened to guys like you and tried to use 22 PPC dies to size brass for the 22 Grendel by all other names. It does NOT work.

You got any more 22lbc barrels in the works? Just did load workup with my new fluted 18” 223 Wylde 3 gun barrel. oh man this thing is sweet. Thanks.

 

[Daddyusmaximus]

Creativity be damned... You probably have more 5.56 / .223 than anything else. Besides, once the balloon goes up, and we're relegated to scrounging for mags off bodies, you'll want a 5.56 weapon.

 

[Powder_Burns]

.375 socom or 6mm arc if I were to build another AR. Look up the ballistics.
This doesn’t take ammo or reloading component availability into account.