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alamo5000
14 February 2016, 16:25
I was talking to my dad and we are talking about doing a .308 build.

I do have a number of questions though before I make the leap. Of course I am window shopping at this point but I am not at all familiar with the components for a .308 build and how those parts (and which parts) differ from an AR platform.

For example I looked on Aero precision's website and their .308 handguards are 'Armalite threaded' or 'Aero/DPMS threaded'.

I also looked on SLR's site and on their handguards it says 'DPMS Low Receiver Height' in part of the description.

I can only deduce that DPMS and Armalite have some kind of technical difference.

If I use a CMT upper and lower would a standard CMC trigger work? What about standard BAD levers or any other standard safety selector? What other parts would be '308 only'... obviously the bolt and barrel... and handguard

I would probably build a 16" or 18" but I am not sure about that yet. The idea would be to have an 800 yard precision build but before I get into that I want to know what all I am getting into.

I am undecided if I want to build an AR platform rifle or buy a bolt gun like Remington 700. Both have their pros and cons and at this point I am just window shopping. I'm not decided yet as to which caliber I want even but the .308 is in the running.

UWone77
14 February 2016, 17:13
Push Pins, Bolt Catch, Magazine on the lower. You can use an AR15 standard receiver extension with a .308 buffer and spring. I'm sure I forgot something.

Upper like you said, you'll have to decide what barrel DPMS vs Armalite pattern and handguard, most are DPMS high pattern.

Otherwise, your standard AR parts will fit.

Josh S.
14 February 2016, 17:17
Here's a link with some pretty good info. I just skimmed through it and learned quite a bit.

http://308ar.com/category/compatibility/

alamo5000
14 February 2016, 17:58
you'll have to decide what barrel DPMS vs Armalite pattern and handguard, most are DPMS high pattern.

I guess I need to research the difference between DPMS and Armalite patterns. I am really not sure what the technical difference is or if it's 6 of one half dozen of the other just in a different pattern... IE competing platforms like M-lok vs keymod... or if there is something more involved. I definitely want to know before I spend a nickel.

Honestly I will probably research this stuff out for a while and when I go, I will go big and get some top shelf stuff. At least top shelf enough to get the job done and make me happy. I am guessing if I put $2000-$2500 into just the rifle (not including optics) I would be able to build something pretty nice.

I still have a few things I want/need to buy... more .223 ammo, a light for my AR...Maybe another upper or two plus optics...I also want to get a few more cases of AK ammo...I also want to get a .30 cal suppressor. Honestly I want to get that done but to do it before I have a gun to put it on kind of makes me wonder where in the pecking order that should go...I also forgot to mention that I want to get some sort of .22 rifle as well...too many wants and not enough cash :)

I've even thought about SBR'ing a .308 lower and basically have two uppers for it. Maybe do a 13.5" upper and an 18" upper... For the .308 I am of the school that using a 24" barrel is pretty useless for that cartridge. I am also leaning towards a .308 merely because it's a widely available cartridge and relatively (to some of the other stuff) cheaper to shoot. I am 100% sure I can hit a 1000 yard shot with a 16 or 18" .308. I am setting my goal at 800 yards and anything beyond that is gravy.

alamo5000
14 February 2016, 18:23
Another question is this... the CMT .308 billet sets don't say if they are DPMS or Armalite. All it says is it will accept Pmags... which I guess is good enough because I have found those to be the best for my purposes.

It also says "UPPER RECEIVER IS COMPATIBLE WITH A WIDE VARIETY OF 308 HANDGUARDS"... that's not very specific. I am not sure what else to look for...

I looked at SLR's site and found this rail just for comparison purposes and because I am familiar with them...

http://slrrifleworks.com/index.php?route=product/product&path=66_107&product_id=480

In the description it says "DPMS LOW receiver height"... how can I know if those two are compatible or not?

Also I found this barrel:

http://ballisticadvantage.com/16-inch-308-gov-mid-cmv-modern-barrel.html

It says "This .308 chambered (DPMS style) 16 inch..."

How can I know if that will work with that upper as well?

Any resources to tell me the differences between these patterns will be helpful.

SINNER
15 February 2016, 09:14
Any pattern barrel will work with any receiver set. If you use a Armalite barrel you must use a Armalite bolt. Same with the DPMS barrels, they must be used with a DPMS pattern bolt.

The receivers are proprietary. Armalite uppers wil not fit on a DPMS lower and vice versa.

DPMS high uppers must be used with high pattern fore ends, low with low.

Armalite uppers must be used with Armalite pattern fore ends. The barrel nuts are a different thread pitch than DPMS and the top rail height is different.

Gas tubes are also different lengths and not cross pattern compatible.

alamo5000
15 February 2016, 09:28
Any pattern barrel will work with any receiver set. If you use a Armalite barrel you must use a Armalite bolt. Same with the DPMS barrels, they must be used with a DPMS pattern bolt.

The receivers are proprietary. Armalite uppers wil not fit on a DPMS lower and vice versa.

DPMS high uppers must be used with high pattern fore ends, low with low.

Armalite uppers must be used with Armalite pattern fore ends. The barrel nuts are a different thread pitch than DPMS and the top rail height is different.

Gas tubes are also different lengths and not cross pattern compatible.

Thanks! That is the kind of stuff I need to know.

Sak007
16 February 2016, 00:58
Armalite will not take pmags and has less options for it. I built a 308 of a Mega Maten set and love it. Now if I were to build one I'd go with the Rainier billet set or the new lightweight Maten in 6.5creedmoor. I'll post my build list when I get to my computer.

Sent from my SGP561 using Tapatalk

SINNER
16 February 2016, 07:22
The lightweight Mega's are going to be sold as complete rifles only from what I have heard. With all the unique dimensions it's not like you would be able to buy anything that would fit it. I can't get any info on if they are following the DPMS G2 dimensions or not. If they are truly designing it themselves parts will likely never become available from other sources.

UWone77
16 February 2016, 07:37
The lightweight Mega's are going to be sold as complete rifles only from what I have heard. With all the unique dimensions it's not like you would be able to buy anything that would fit it. I can't get any info on if they are following the DPMS G2 dimensions or not. If they are truly designing it themselves parts will likely never become available from other sources.

Yep, but they did leave the door open for receivers sets down the road. That wouldn't surprise me as $2500-2800 rifles aren't exactly flying off the shelves the last few years.

Alamo, I'd go with DPMS pattern, just a lot more options out there.

velocity2006
16 February 2016, 10:59
That wouldn't surprise me as $2500-2800 rifles aren't exactly flying off the shelves the last few years.


Agreed, and I think lately a lot more people are building their own DIY rifles from receivers. I think it would be a mistake to not offer them eventually, I would buy a set lol.

alamo5000
16 February 2016, 17:50
Alamo, I'd go with DPMS pattern, just a lot more options out there.

I have done a little digging and I learned a little bit today. For future reference if some other person finds this thread I will put up my findings for them....

I have found that CMT Tactical 308 sets are DPMS pattern and the CMT 308 upper is the HIGH profile which means the rail on the upper receiver is slightly thicker metal which makes the rail sit higher.

I found out what the difference is between High and Low profile when it comes to .308 uppers. Here are more details.

This link here will help:

https://troyind.com/sites/troyind.com/files/rtc-attachments/DPMS_RECEIVERS_COMPARE.pdf

But basically the top part of the upper that is actually the rail section is machined off more for the low profile version. For the high profile version it is thicker. Specifically the low profile is 1/8" thick and the high profile is 3/16" thick. If you measure the thickness of the tab where the charging handle goes you can find out which one you have (or want to get)...

What difference does that make? Well if you have a high and get a low rail your flat top will step down from the upper receiver to the hand guard and will not have the correct fit. Conversely if you have a low profile upper and get a high rail your flat top will have a step up where the rail meets the receiver.

I am learning new stuff all the time. [:D] Good stuff to know before I start blowing money.