[Cnynrat]

OK guys, I’m looking for some advice to help me figure out what options to pick for my first SUR-15 project. I'm pretty new at this, but have been spending some time reading through the material on the forum and elsewhere.

First, what do I want to do with the weapon? Realistically, it’s probably going to mainly be used for target shooting, and maybe some plinking out in the desert. I suppose in some wild SHTF scenario it might be called upon in a personal defense role, or maybe putting some food on the table. I’m trying to remain hopeful that things won’t reach that point. Mostly I’m doing this because I want to, because I can, and because I think it will be a fun project that will also provide a good learning experience.

I’ve already procured a CMMG lower, a lower parts kit, and a buffer tube (with all the related buffer tube parts).

I’m pretty sure I want to go with the MagPul CTR stock. I like the ability to solidly lock it on the buffer tube, and I like the look. I’m still looking around for one in stock at a reasonable price.

I’m overwhelmed with all the choices on the upper. I’ve studied this post: http://everything you want know about ar-15 models/. My preliminary thoughts are influenced by the information in the writeup by JWise. Based on his evaluations I’m kind of leaning towards a CMMG upper. I haven’t completely decided but I may go for a complete upper for this first gun, and then maybe build another that I build up completely from components. This choice is about expediency – not sure I have the patience at this point to track down available stock on all the individual pieces.

Upper Type: I’m thinking of an A3 style upper. No particular reason other than I like the look, and will want to put optics on the gun eventually.

M4 Feed Ramps: I understand these are desirable to help ensure reliable operation. But then I realize the choice isn’t quite that simple because CMMG (maybe others?) offers the choice between “anodized feed ramps” or “extended polished feed ramps”. Not a big up charge for the later ($10), but is it worth it? What are the tradeoffs?

Barrel: Probably leaning towards a 16” Government profile, chrome lined, 1/7 twist. I’ve given some thought to an 18” barrel, since I don’t see close quarters work as being a really high priority for this gun. Any thoughts on the alternatives here?

Gas Length: Leaning towards mid length – is that a reasonable choice?

Front Sight/Glass Block: Here’s where the options seem to get out of hand. My guess is I will initially build and shoot the gun with iron sights, but will eventually want to put optics on the gun. Given that, is there a good choice for front sight and gas block that will eventually be compatible with optics? Do I necessarily want a folding sight to be compatible with the optics?

Rear Sight: Basically, I have the same questions about what makes sense to do initially if I plan to add optics later. Is there a good rear sight that will work well until I get optics and then be compatible with optics down the road, or do I need to be thinking of changing the sights to some BUIS later when the optics are installed?

Handguards: Probably will just get standard handguards to start with, and think about upgrading to some sort of rail system down the road. That should save a bit of money up front, and I’ll probably have a better idea how we’re using the weapon by then

Flash Suppressor: Another area where there are too many choices! What works, what doesn’t?

Thanks in advance for any and all advice!

[Dillinger]

I’ve already procured a CMMG lower, a lower parts kit, and a buffer tube (with all the related buffer tube parts).

Excellent Start. You are already halfway there.

I’m pretty sure I want to go with the MagPul CTR stock. I like the ability to solidly lock it on the buffer tube, and I like the look. I’m still looking around for one in stock at a reasonable price.

Another really good choice. Very durable and well made. It's a bit pricey, but it is a good unit.

I’m kind of leaning towards a CMMG upper.

a receiver is a receiver in this day and age. As long as you aren't buying one from Fred's Tire Shop and AR Manufacturing, you are probably getting a good one. Just stay away from anything that is made of pot metal or imported from China and you will be fine. The whole matching upper and lower thing is blown completely out of proportion by the Internetz being Sirrus Bidness.

I haven’t completely decided but I may go for a complete upper for this first gun, and then maybe build another that I build up completely from components.

Nothing wrong with that choice at all. Get a unit that is up and running, then you can hand build a complete upper with your specs, even in a different caliber and pin it in place to your existing lower. One of the many wonders of the AR platform.

M4 Feed Ramps: I understand these are desirable to help ensure reliable operation. But then I realize the choice isn’t quite that simple because CMMG (maybe others?) offers the choice between “anodized feed ramps” or “extended polished feed ramps”. Not a big up charge for the later ($10), but is it worth it? What are the tradeoffs?

Can of worms here and I don't have the energy to fight this particular battle again. I'll go with the rest of the Internetz and say spring for the extra $10 because it will make it SOOOO much more reliable. I don't really believe that, but the conventional wisdom is that under HEAVY sustained fire, in combat, you NEED to have the smoothest, most shiny feed ramps as possible or you will hang a round right as the Zombies are breaking through the wire. I think the feed ramp issue, quite frankly, is completly blown out of proportion and if you are using quality mags, and you are taking care of your weapon, it will take care of you. Ask yourself this, why is it called an M4 feed ramp and why would I need it on a semi automatic version? An M4 is fully automatic version carbine. I'm just saying...LOL

quote]
Barrel: Probably leaning towards a 16” Government profile, chrome lined, 1/7 twist. I’ve given some thought to an 18” barrel, since I don’t see close quarters work as being a really high priority for this gun. Any thoughts on the alternatives here?[/quote]

1:7 is not the best choice for the available bullet weights in common "retail" land....

1:7 is a faster spinning bullet rate, which means you have to shoot the heavier bullets out of them ( probably in the 77 grain, or higher, environment ).

Most of the common civilian and military stuff is either 55 grain or 62 grain, which is where the 1:9 Twist Rate barrel comes in. With a faster twist rate, 1:7, and the right conditions like high heat and low moisture, you could very easily overspin a 55 grain bullet and get it to particl-ize ( I made that word up ) and therefor would be useless in the field.

Now, if you were reloading, the 1:7 twist with the heavy bullets would give you great knock down potential over someone shooting the 55 grainers all day long.

Gas Length: Leaning towards mid length – is that a reasonable choice?

I have a mid length gas tube on my 17" and it works fine. The difference is that you have to make sure the gun is tuned for the pressure of the rounds that you will be firing, because gas from the front of the barrel isn't going to be as "strong" as gas bled off in the middle. There isn't much difference and as long as you aren't shooting subsonic loads, you probably won't notice. I like to have the entire gas block and tube protected under my fore-end, but that is a personal choice. We build both around the shop.

Front Sight/Glass Block: Here’s where the options seem to get out of hand. My guess is I will initially build and shoot the gun with iron sights, but will eventually want to put optics on the gun. Given that, is there a good choice for front sight and gas block that will eventually be compatible with optics? Do I necessarily want a folding sight to be compatible with the optics?

Every good field AR should have BUIS ( Back Up Iron Sights in case you ever wondered what that stood for ). Optics fail. Scopes get cracked, fog up, batteries die on EoTechs, etc. Personally, I don't co witness my iron sights with my optics. I use one or the other. Alot of people prefer to co-witness their sights, using both at the same time. I prefer to have fold down sights and a quick release on my optics platform. It's a personal preference thing.

Rear Sight: Basically, I have the same questions about what makes sense to do initially if I plan to add optics later. Is there a good rear sight that will work well until I get optics and then be compatible with optics down the road, or do I need to be thinking of changing the sights to some BUIS later when the optics are installed?

See above: Personal Preference. YHM and Troy industries both make excellent fold down front and rear sights to be used either co-witness or alone.

Handguards: Probably will just get standard handguards to start with, and think about upgrading to some sort of rail system down the road. That should save a bit of money up front, and I’ll probably have a better idea how we’re using the weapon by then

I would spend the extra cash and get a free floated handguard now. Ask Junho, he went with the clamshell, then upgraded after the fact and likes his free float better. It's more accurate and it dissipates heat better. You don't need a $300 4-rail system now. There are several flee float tubes that have one rail and do everything they need too. Alot of the 4 rail systems that guys get, they end up buying special covers to avoid losing chunks of their flesh to the rails anyways. LOL

JD

[bobbyb13]

The only problem I can see in your project is the difficulty in finding a freaking upper, without the 16 week wait. Wait a minute, nah it's just the voices again.

[Cnynrat]

Thanks for the advice JD.


I hear ya on the wait bobbyb13. I'm resigning myself that this will probably be a lesson in patience as well.

[Cnynrat]

So with JD's advice in hand about barrel twist, I've decided to take a different approach and buy the parts to build up my own upper. I think that should let me get the combination of features I want.

I get it that a receiver is a receiver is a receiver, as long as it isn't Chinese pot metal. That said, does anyone have any experience with a non-brand name upper receiver such as this one: BC USA Upper. I assume "USGI Contractor" indicates it's made by someone who builds stuff for the U.S. Government. Is this likely to be a quality part, or should I go for something different?

Next, it looks like one of the challenges will be finding a barrel - not many in stock out there that I've found. I assume this is a component that may have a significant affect on the performance of the weapon. What brands do you guys like? Any clues on a good source?

As always, thanks for helping to enlighten a noob.

[hillbilly68]

Concur with what JD said (like thats a big stretch or the imagination!).

Yep, free float to start. A3 receiver, dont bother buying the carry handle, with a low profile gas block and a good set of BUIS. Dont go cheap on the BUIS, dont let the "backup" term lead you to cut costs Stay in the 1:9 rate in the 16in bbl.

Stock. The CTR is a great stock, but they are proud of it. The MOE version will lock up just as tight with a good mil spec extension (hint: make sure you know which one you have). And it is about half the cost. The only thing is it takes away a QR swivel option you have with the CTR.

Just dont hang a bunch of useless crap off it. Just because you have rails doesnt mean you have to fill every inch of rail space, you'll watse your money on stuff you dont need.

And get ready to wait. And wait. And when you are tired of waiting for the big brown truck, wait some more.

Good luck, throw up a pic or two when you get her built!

[Dillinger]

Originally Posted by Cnynrat

So with JD's advice in hand about barrel twist, I've decided to take a different approach and buy the parts to build up my own upper. I think that should let me get the combination of features I want.

Good for you. I think that everyone should try to build their own at least once. It will teach you TONS about the weapon itself and how it works. Plus there is a serious sense of pride in the fact that I built this.

That said, does anyone have any experience with a non-brand name upper receiver such as this one: BC USA Upper.

Nothing wrong with that upper at all. It appears to only be about $16 bucks more than the stripped version and it comes with the forward assist and the cover in place. It would probably be about the same to buy the stripped version and the parts ( plus shipping ) so I would say you are spot on with that one. Plus it's in stock, which is saying something right now. 7075 aluminum, so it should be every bit as good as any of the other ones out there that are hand carved by the Dwarves in the furnaces of Middle Earth.

Next, it looks like one of the challenges will be finding a barrel - not many in stock out there that I've found. I assume this is a component that may have a significant affect on the performance of the weapon. What brands do you guys like? Any clues on a good source?

A barrel is going to make all the difference in the world. Getting a basic GI chrome lined barrel will be easiest, but it won't shoot as well as a custom ( obviously ). That said, if you plan on doing a 16" ( which I think you were ) the amount of difference you are going to see as a basic shooter, is going to small, but not insignificant. A decent barrel and a free floated fore end, plus a good trigger and some practice is equal to a high end barrel in the hands of a novice.

As for a source - good "F"ing luck these days I am afraid.. You can expect everyone to be on a MINIMUM 120 day back order. Some places aren't even selling single barrels any more, they are selling minimum packages of 10 or 20 for shops all around the country.

If you can find an LMT or DPMS or even a Stag, in a 16" I would snap it up if you can afford it. They are in pretty high demand right now though - almost impossible to find without back order.

The best barrels by far, in our shops opinion, are Kreiger Barrels and they make them for AR's as well. Problem is, for the money, in a 16" platform, you are getting WAY TOO much barrel and it will never get the kind of accuracy out of the gun you are putting it on. If you were building a 20" heavy barrel varmint shooter, that would be another story...

JD