AR57 Builds

Stumbled upon an AR57 upper a week ago and for the price had to get it. Don't see them often enough in person and it was the upper that got me into looking more and more into the AR market. Anyone have any tips on a build? Right now it's sporting a 6" barrel which I've been trying to get in contact with AR57center to get info about removing it to replace it with a 16" barrel and trying to build a compact setup around it. I know they work well with Milspec trigger groups, but didn't know if anyone on here has thrown a drop in trigger group and had it work without issues. Had a spare pistol built lower sitting around so that's where it's on. Waiting to hear back from AR57center before jumping on a new barrel and ordering the buffer for it prior to taking it out to the range.

I have 1 in my to do list . It's a fun caliber :-)

I'm torn whether to go with the 16" barrel or to stick with the 6" or get the 12" and get the best of both worlds but keep it in a pistol form until I decide I'm interested in SBRing it. 6" seems a bit useless IMO and dangerous unless I suppress it as the barrel rides under the monolithic handguard and probably will be a reason for a few burns for someone holding it without a suppressor on it.

I have a 12" in an SBR and love it. I put a Geissele SD-3G trigger in it and it works flawlessly. I have not done a barrel swap so I cannot help you there.

I will have my 12 inch pistol build by next week. Will post pictures then.

I've got the 12" and the 6" with a suppressor in the handguard. Both fun uppers. If I want to run the 12" suppressed, I use an AAC M4-2000.

Here are a couple videos of the 12" AR57 on a registered receiver.


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And suppressed with an AAC M4-2000


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I'm now torn whether or not to get the 12" or the 16" now... Unless I can find someone who has a 16" and wants to swap barrels, then I'll just buy a 12" to sit aside, haha. Anyone have any issues with rounds going off out of battery with high rates of semi fire? Since this is a blow back system I know it's easier to have an issue with riding the bolt home with the trigger. The reason I asked was I was considering tinkering with a Franklin Armory binary trigger system on the AR57, but don't want to damage the upper.

Does the 5.7 take a standard carbine buffer/spring set?

No on the buffer, yes on the spring.

Mine came with the buffer

I got mine used as an upper with a bunch of ammo, picking up the mags out of state soon for it.

Forgot to mention I went with the 16" fluted barrel as well as ordered the buffer and hopefully it will show up sometime next week since I ordered it Monday night. I'll hold onto the 6" incase I get curious about NFA...

I'm watching this thread, while other priorities are ahead of this. A 5.7 AR ha been on my wish list for a long time, party of the reason I bought some extra post FSA lowers which should be fine with a AR57 upper.

Jim, I was in the same boat. AR57's are what caught my attention to the customized AR market back in 2009 (I think?) and I wanted one since. Atlantic Guns in Rockville had one at the time, but were asking $950 for the upper with a 16" barrel, no muzzle device and no mag (though it had a 10 rounder on it when I was looking at it.) When I asked how much the mag was they told me it wasn't for sale, just on the rifle to show how the mag fit and they wouldn't sell it or order 10 rounders for it because "they did not exist" and were dead set on the one in house being a 50 count even though it was stamped '10' on it. Since then I'd never seen any local and the consistent ~$800 tag that had been on them for the years I got into AR's pulled me away from them since AR's were running that complete at the time. Jumping on this upper far below that, inclusive of 3 mags I picked up and the new barrel and buffer that I ordered was a no brainer.

Planning on ordering some parts to get it in a 'shootable' state and up in the air on a few. First off is a muzzle device. I know the 5.56 devices work on the 5.7, but I'm not sure what I want to go with. Since the 5.7 is a soft shooter to begin with, I'd like to expand on that and have a muzzle device that will assist in reducing the minimal rise that's there to make this more of a tack driver at 50/75 yards. Was considering something that was produced to support suppressors, but since I'm not sure which can I might tinker around on this I'm not sure it's worth getting one can muzzle device to possibly replace it later. That said the ones in mind were:

AAC Flash Hider -


Or

GEMTECH 5.56 Muzzle Break -


Figure both options have a decent range of suppressors, but then I'm locked into their mounting style or have to replace it later. At least for the GEMTECH I can slap on a Blast Jacket on it until I go suppressed. Even the SilencerCo option isn't bad.

The other thing that is up in the air is sights/optics. Again, I don't plan on taking this really past 100 yards and more realistically most likely 75 being the top end. Figure I'd get sum backup sights and run a red dot of some sort like I've been doing on a few of my other AR's, but I'm not sure what to go with. Only backup sights I've got experience with are the Magpul ones and I'd like to try something different to keep my rifles from being the same thing just a different caliber, then again I get if it works why bother changing it. But as for the red dot I've had great success with a Bushnell TRS-25 and a Holosun HS403GL. I'd like to stick away from the Holosun's right now as I've come to loath turning it on and off, maybe considering a Vortex Sparc 2? Should be small enough to mount with some back up irons and still be able to clear slapping in a mag. Thoughts?

I have never had a problem with the sound of my 12" AR57 SBR but if you are set on suppressing it you should plan with that in mind. Do you already have a suppressor? If so will that suppressor work on 5.7? Do you plan on getting a suppressor for another caliber that will work with 5.7? If so buy the muzzle device that works with that suppressor. The 5.7 from a rifle is VERY controllable, my wife has absolutely no problem shredding the bullseye at 50 yards with the factory muzzle break and an aimpoint micro. Since the 5.7 round is always supersonic and not that loud to begin with I wouldn't spend the money for a dedicated suppressor but don't let me stop you.

As far as optics I think a red dot is the way to go. The 12" rifle is a tack driver at 50 but by 100 yards it starts to open up a bit more, your 16" barrel might be better at 100 but either way it's not a real long distance gun. With normal shooting you will not have to worry about the recoil affecting your zero so you don't need to spend a fortune on a red dot. The Vortex Sparc comes with a multi-height mounting system so it should cowitness with any back up iron sights. Do you plan on co-witnessing your BUIS to the red dot or just keeping them folded down as a true back up? Do you want fold down sights or fixed sights? You can spend quite a bit on iron sights but for a 5.7 gun I would not be willing to spend $200+ when I already have a red dot.

I've kept out of the can market for a while because I didn't want to get a can per caliber as it use to be years back. As of the recent years, it's been a lot easier to get a multipurpose can that actually works through multi calibers. Doesn't do an amazing job as a dedicated can for a caliber, but something is better than nothing. I plan on getting into the can market soon once I get my 300 blackout build complete and figured that the 5.7 would be neat suppressed. It's not the sole intended caliber for suppression as it will be using a 30 cal can. This is a longterm plan, so I'm not too worried about a solution for now. Also, the reason I was thinking of suppressing this is to make it a go to groundhog gun besides a niche range rifle. With all the recent property/crop damage I've got in my yard and garden and how prevalent these critter seem to be I'm getting tired of trapping them and filling their burrows that they make under my sheds and in the yard. I've restrained from dropping them since I'm in a semi residential area (a few houses in farm land) and unsure how the neighbors are going to react to a round or two going off.

The upper I bought came with a 6" barrel that did not include a muzzle device as the previous owner the shop got it from seems to believe it was a dedicated suppressed upper before the guy let it go. This was based by the barrel length and what looks to be the remains of some rockset on the threads of the 6" barrel. I'm basically just in search of something, and if it's going to be something besides a standard A2 cage, I'd like it to be functional. Like you said, the 5.7 is a soft shooter with very minimal flip if any. I'd like to reduce that as much closer to nothing if possible with some muzzle device, otherwise I'll just grab an A2 or something neat and get the upper ready to roll.

As for the sight/optic, I just figure some backups would be a nice to have/mix up shooting. Whatever I go with for the optic for this setup will most likely end up getting shared with another upper as 5.7 isn't exactly cheap enough to shoot on the regular or easy to prep for reload if I get into that. I don't co witness my other setups, but that's because I either have irons, red dots or a scope. I've been meaning to get backups for some of my setups, but systems with dedicated red dots will have irons for backup purposes only. In the case of this setup I might have to go with a co witnessed optic to irons so I can easily set the red dot back up to the upper if it's been hopped around.

Also, would like to mention that the 57center.com support has been really helpful over email once you get passed the odd hours of support. If anyone is hesitant into getting their upper and have questions or need parts they are extremely helpful.

Parts are in route still and should be here Wednesday. Thanks to a local shop I'll be able to swing in and get the barrel replaced with the 16"er hopefully same day. FYI, for anyone looking to swap a barrel on this upper, you're going to need to heat the barrel with propane and use an upper jig (not a standard upper vice jig) to mount the upper to a solid work space. 57center supposedly packaged replacement instructions per my request that were written by their technical staff with the barrel so I'll post up more details when it shows up Wednesday. Still on the fence on what muzzle device to go with. Had a Troy Claymore sitting in the parts bin, so I think I'll give that a whirl for a bit until I decide which other way I plan on going. Going to be mounted up on a Pre-SB281 lower for a bit until I decide what I want to have it on as a dedicated setup.

Request for pics to help figure out barrel installation. The barrel that I got in from 57Center protrudes about 1/8th of an inch into the loading port of the receiver and I just want to be sure that it's suppose to. I spoke to one of their techs, but I forgot to ask the about that part of the install *doh*. Can anyone with an AR57 upper help me out with some pics of where the barrel meets the bolt and where the barrel meets the receiver? Just want to be sure I bottom out the barrel to the 25ft/lb's they mentioned and don't require any shims between the barrel receiver and it's ok for the barrel to stick an 1/8th inch into the receiver.

I used to be able to find the 12 inch upper for sale and now that I'm looking for one, all I can find is the 16. I would rather not have to do a barrel swap when I will probably never use the 16 inch. Anyone can point me in the right direction?