# AR build, what caliber?



## Tuffdaddy (Oct 26, 2012)

So I'm jumping into the world of building an AR. The problem I'm having is deciding what caliber. I currently have a RRA in .223/5.56. I could build another in this caliber, but there are so many other options out there, that I'd look at another caliber first.

I'm the kind of guy that wants his guns to have a purpose (read, would like to hunt with it along with some target shooting). Im also a little cautious in using an off caliber if it's not going to be around 10-20 years down the road.

Give me some ideas to help me decide. AR15 or AR10 platforms. Ready....go!


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## sneakygroundbuzzard (Nov 1, 2012)

hmmmmmmm thats a good question

are you going to supress it? if so then i would say 300 black out

do you want to be able to hunt big game,shoot long distances? then .308

or are you going to use it for smaller furry critters like yotes and the like?

there are so many choices in calibers one can go with on this platform

ive been contemplating this very question myself

for me i think i am going to go with a .308

seen a nice one based on the AR platform,but it was a bolt action and not blow back like a true AR

wife has been hinting sho would like one in 9mm


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## Tuffdaddy (Oct 26, 2012)

I've been dreaming of a 300blk but won't be suppressing unless we get lucky and they take it out of the nfa.

I have a 308 bolt gun now, or I would have jumped on that. I'd possibly shoot coyotes with it, maybe wolfs if they ever de-list them here, maybe a pig trip down the road...

I've been thinking of .204 ruger, then 6.5 credemore, kind of cautious about the 6.8 and 6.5 Grendel. Then I looked at maybe 243. I have to figure out if it'll be ar10 or ar15 framed. Then I suppose I can build a few different uppers.


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## Agney5 (Sep 28, 2013)

AR 15 I'd go 6mm AR or AR turbo. That is if you're willing to reload.


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## Tuffdaddy (Oct 26, 2012)

The more I look at an ar10 in 243, the more I'm liking it. Pretty versatile but practical caliber. And ammo should be pretty safe in the future.


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## Tuffdaddy (Oct 26, 2012)

6mm pretty close to 243? Haven't heard of ar turbo.

I'll eventually reload, but not for a year or two. No time yet to get too deep into that.


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## youngdon (Mar 10, 2010)

.243 is 6mm.. exact same diameter


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## Tuffdaddy (Oct 26, 2012)

.243 seems like a good route to go. Ammo is readily available, can hunt small stuff up to whitetails, can shoot long distances if I ever get the opportunity.

Downsides?


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## Tuffdaddy (Oct 26, 2012)

Dang, just read more into the 6.8 SPC II. Seems like a good hunting round, but not as much long range capability (although I did see a certain load would do 1000 yards. I doubt I'll get the opportunity to shoot 1000 yards though, and if I do, I have my 308.

Anyone have experience with the 6.8? Looks like a few foreign militaries are adopting the round so hopefully that is good news for ammo availability long term.


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## bar-d (Feb 3, 2010)

I have built two 6.8 SPC rifles. Ammo is much more available now than when I started in the caliber several years ago. I have taken deer, hogs and coyotes with the caliber and IMHO it is one of the best alternative AR calibers. Is it a 1000 yd cartridge? No. But you would be hard pressed to find a better cartridge for the AR-15 platform for up to deer size game out to 300 yds. Again this is my opinion based on my experiences. Check out 68forums.com and you will find everything you ever wanted to know about the caliber.

:hunter:


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## Tuffdaddy (Oct 26, 2012)

Awesome! I just read a pretty extensive review of the 6.8 and it said good things about it, including availability of ammo.

I like that it's an ar15 platform too. I'll check out the 68forums for sure.

Now to figure out what to use for a lower. Suggestions?


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## sneakygroundbuzzard (Nov 1, 2012)

in my opinion MEGA ARMS is hard to beat

a little more expensive than some(i paid $110)

but you get what you pay for

perfect fit and finish,plus it has a screw in it to help tighten the lower to the upper

i know some say you want the slop,but these rifles we build will more than likely never be used in battle conditions. and if and when the time comes that it will be,well then just back out the screw a tad bit and you have the slop for it.

there are a lot of manufacturers out there that sell lowers,but really only like four companies that make them for the sellers. but they make them to each companies specs.not all companies have the exact same specs,even if they claim its mil spec.

one thing i do know is that if you order a lower and an upper from most reputable companies,they will hand fit them for proper fit before they ship them to you.

rock river arms i know for fact will do this,they say so right on their site.

my next build will be with one of their hand fitted upper/lower combos.

theirs are tight from the factory,some have complained to tight. but the more times you seperate the upper and lower,the better the fit becomes.


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## bar-d (Feb 3, 2010)

Tuffdaddy said:


> Now to figure out what to use for a lower. Suggestions?


Whatever you are comfortable spending. I use Spike's Tactical and Anderson lowers. I do suggest you use a quality LPK, it makes a big difference in function.


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## Tuffdaddy (Oct 26, 2012)

Thanks guys. I'll look around at some lowers and see what I decide. I've seen the spikes and they have some fun designs on them. I've heard of the others, but wasn't sure if there are big differences. You get a bunch of different opinions searching google.

What are you running for a lpk?

I'll have to check out some MI lowers. They aren't too far from where I work.


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## sneakygroundbuzzard (Nov 1, 2012)

then there is always the option of an 80% lower

you have to finish the machining of it your self

for the money, a RRA stage two trigger group is hard to beat

slick as glass,breaks crisp,and under a $100

for everything you want to know,need to know about AR15 platform guns go to

AR15.com


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## Tuffdaddy (Oct 26, 2012)

Thanks again SGB. This is my first build, so you may get questions from me at some point. I'll probably be buying parts at different times so the wig can't yell at me for building this lol. Might take me some time, but at least by deciding on a caliber, I can get the lower for starters, then start saving and buying as time goes by.

The bonus is I booked a few musky guide trips this year already, and that's all fun money for me. .


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## sneakygroundbuzzard (Nov 1, 2012)

she should appreciate you building it yourself

costs about half as much as buying a complete rifle

im saving up to get a lower/upper combo right now

then its the barrel,then the lpk,hand guard etc etc


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## youngdon (Mar 10, 2010)

Here is my 2cents on the slop issue. You don't want or need it between the upper and lower, and certainly not in the trigger, but the bolt carrier group will function better with it, as a little dirt or gunk won't impede the function. The upper and lower should mate up fairly tight, as then you will have the exact same sight pattern every time. Some units have a screw to tighten things between the two, other units can be made tighter by way of a wedge.


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## Bigdrowdy1 (Jan 29, 2010)

I have 2 6.8SPCII myself and are a great round. Like BarD mentioned they are a good 300 yard gun.Loaded you can take cyotes to hogs and whitetails and be very happy with the results.I also have a 223 cal and hunt with it more just because it is my comfort cushion but I aint afraid to take one of the 6.8 out anytime. Waiting on my Omega silencer to come in for night hunting hogs. Great round I like it alot.


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## Tuffdaddy (Oct 26, 2012)

Nice, thanks for the input guys. Now to find a lower and LPK to get started.

Trying to keep it a little lighter than my 223. It's a RRA Operator and it is heavy!! Time for Internet research on the build. The lower looks fairly straightforward. Haven't looked at uppers yet though.


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## azpredatorhunter (Jul 24, 2012)

If I were to get another one... I think I would get it in .22-250 Remington...


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## sneakygroundbuzzard (Nov 1, 2012)

i would keep away from poly lowers

to keep it light you could go with a pencil profile barrel

a minimalist stock

there are some light weight hand guards out there,but they get pricey

low profile gas block.

i know what you mean about the RRA operator being heavy,i have an elite operator II and its a tank

but i like it and its the one that gets used the most


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## youngdon (Mar 10, 2010)

azpredatorhunter said:


> If I were to get another one... I think I would get it in .22-250 Remington...


That would require an AR-10 type setup.


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## youngdon (Mar 10, 2010)

sneakygroundbuzzard said:


> i would keep away from poly lowers
> 
> to keep it light you could go with a pencil profile barrel
> 
> ...


I have a poly lower and it certainly lessens the weight. From a mechanical standpoint the poly lowers are no different than a glock or any of the polymer handguns, the handguns do run at substantially lower pressures, but they also have a (in many cases) polymer upper frame enveloping a few metal parts. As the AR platform is built in two distinct halves with the lower containing the mag well and the fire control group (trigger), the upper contains all the components that come under pressure from a fired round ie the chamber, barrel, bolt carrier and its group with the recoil buffer taking a punch with every shot. Would I buy another, yes I would. However I'd replace the trigger group right away. the polymers trigger groups really aren't that bad, better than some stock ones I've shot, but the polymers take a hundred rounds or so to become decent. For long range work, on prairie dogs, I'd rather have a lighter trigger than the polymer affords me.


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## sneakygroundbuzzard (Nov 1, 2012)

poly lowers have an issue with the housing for the buffer tube breaking and at the take down pins after some use

not to say it "will" happen

but has happened enough for me to avoid wanting one

remember the glock was designed(engineered) to be used with a poly frame

the AR was designed(engineered) to have an aluminum lower/upper assy

you cant just take an engineered design and start using different material with the same dimensions and expect them to last under the same kind of use


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## Tuffdaddy (Oct 26, 2012)

The elite operator II is exactly what I have. Tank of a gun for sure, but it's a shooter as well.

I know you guys mentioned Spikes for a lower, but any others you'd recommend as well? Was looking to keep it made of metal (non poly) for this build. There's a ton out there, and I don't need the most inexpensive, but also don't need the best of the best.


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## Bigdrowdy1 (Jan 29, 2010)

PSA, Surplus ammo,Brownell's, Mega Arms, RRA, DPMS, Olympia arms and the list goes on. I have A match mega set, Olympia Arms and a Surplus ammo lower. I have had 0 problems from any of them. If your looking into the 6.8 SPC II check out AR-15 performance arms. They don't sell lowers but they make their own rifles with melonite barrels hammer forged with their 5r rifling. The also do 223/556 and some other special barrels but they specialize in the 6.8. JYFI.

Rodney


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## sneakygroundbuzzard (Nov 1, 2012)

JSE surplus currently has the Anderson 6.8 stripped lower for $60

what ever you go with,the lowe will need to be sent to an FFA

when you pick it up from have them list it as a "pistol"

that way you can put a pistol length upper on it(with no stock of vfg) or use it as a rifle

but if its originally listed as a rifle it must stay as a rifle


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## Boxerboxer (Aug 6, 2015)

sneakygroundbuzzard said:


> JSE surplus currently has the Anderson 6.8 stripped lower for $60
> 
> what ever you go with,the lowe will need to be sent to an FFA
> when you pick it up from have them list it as a "pistol"
> ...


This isn't 100% accurate - stripped lowers are neither rifle nor pistol. Until the receiver is mated with a barrel, the ATF does not consider it to be a rifle, and it can this be built into a pistol, even if it has had a stock attached (source, including ATF letter: http://www.typicalshooter.com/atf-putting-a-stock-on-an-ar-15-lower-does-not-make-it-a-rifle/).

The bit about once a rifle always a rifle is true though, and the bit about the FFL.

I have to ask though, why pay an extra $20 for a lower that says "6.8" instead of "multi-cal"?


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## youngdon (Mar 10, 2010)

sneakygroundbuzzard said:


> you cant just take an engineered design and start using different material with the same dimensions and expect them to last under the same kind of use


I agree, however you know that they didn't just go willy-nilly and make one up in a shed somplace.


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## rotty (Oct 20, 2015)

6.5 grendel.


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## pokeyjeeper (Sep 5, 2013)

the 22-250 can be made to run on an ar15 lower Olympic arms makes one and she is sweet the one I have runs great but there lower is not a stander lower it has been opened up good luck with your build


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## youngdon (Mar 10, 2010)

Will their lower accept a standard upper ?


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## pokeyjeeper (Sep 5, 2013)

yes it will all you need to do is change out the mag retainer


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