Bump for the hunt.

Yes.  You'll need to use an Armalite BCG.  IIRC, the fit is very tight when trying to put Armalite patterned barrels into SR25/DPMS pattern uppers.




Yes
to both.  The UBR will need a shorter buffer when used on a .308 than
it will when used on a 15.  DPMS and Slash (heavybuffers.com) both sell a
buffer of the required length.






POF is DPMS pattern, you shouldn't need any sleeves to fit the upper to the lower.  Yes the POF can use PMags.
 




 



 



 

You do need sleeves as the DPMS uses the .278" pins and the POF uses .250" pins.

Wasn't aware of that, thanks for the clarification.

I can second this as I got that response straight from POF themselves...........

What's it take to get a lr308 DPMS to rue 300wsm just a barrel or is it a complete upper
With different BCG?

You are going to need at least the chamber reamed and a different bolt. I have been toying with this idea so I'm in for the responses.

What upper receiver block should I buy/use to build/barrel etc. my Maten Upper?

Should be noted that CMMG no longer makes a model that takes G3 magazines.... Discontinued

Did any of them ever hit the retail market in any quantity?

I don't think so... the tech I spoke with basically came out and said its discontinued due to having too many problems that couldn't be worked out.

What AR 308 specific tools do I need?

so are only specific hand guards going to work with a cmmg mk3 upper receiver? I don't believe it's the Low Profile ones like the new dpms. I was hoping it'd be compatible with standard ar15 hand guards but now that i see it needs a different barrel nut i'm a bit worried.

ETA: well some further research answered my own question. nevermind!

So i read on the first page of this thread that .35 rem.  is available as another upper.  Ive used my google Fu and have came up with nothing but two instances where someone has mentioned possibly maybe trying to convert a upper to this caliber.  Is anyone making a .35 rem upper reciever and where can i get one?  Much appreciated

1st post and building my 1st AR.  

I have a custom lower from a local Arizona company.  It is a DPMS type and compatible with DPMS uppers.  Are Rock River uppers compatible with DPMS lowers?  

I apologize if this has already been covered.  I read through this thread a few times and didn't see it.

Thanks,

Greg

I've thought of this too, I'm pretty sure I could bore out my bolt.

I'm a little daunted by the prospect of getting it to feed.

A .358 Winchester would be a lot easier, I think.

The RRA is longer than the DPMS and NOT compatable.

It looks like Armalite grinds their bolts to the larger internal diameter. And don't forget you have to tweak the extractor too.

this combo also works Troy DPMS barrel nut with a TROY armalite rail..lines up perfect.

I have read through the thread but would just like someone in the know to confirm what is noted on page 1 - is it correct that a Remingtron R25 free float tube and ring cannot be used on a RRA LAR8?  Thanks in advance!

Good info..tag for later reference....

I have an SI-Defense matched pair. Will other forward assists and dust covers work on this upper? Will Ar-15 forward assist work on this upper?

LMT, S&W, LWRC, Colt, HK, Sig, Nemo Arms

I see some topics on the site about the trajectory of the .223 bullet. Can anyone post some external ballistics for the .308?

 Maybe a trajectory chart with different bullets?

   .308:  Resizing brass that was shot in a worn out machine gun SUCKS!!

Looks like this thread needs lots of love now that PSA is selling 308's.

Also I didn't see Magpul listed under sr-25 mags

Some additions for the OP

Sources for Stripped Uppers & Lowers:
Mega Arms
Aero Precision
Rainier Arms
Palmetto State Armory / PTAC

Sources for Bolts:
Aero precision
Palmetto State Armory / PTAC
JP Enterprises Inc
Tactical Ambush

Barrels:
Rainier Arms
Mega Arms
Palmetto State Armory / PTAC
Aero Precision

Thanks OP;

Magpul SR-25 pattern mags: 25, 20, 10 rnd

GA Precision is not Georgia Precision.

Also, they are no longer based off the AR-10 design.

The GAP-10 uses POF/Hogan style receivers and handguards, with GA Precision's approach to making a super accurate gas gun. It is one of the many variations of the AR-10 receiver set design, but there are unique pin diameters and lengths to the POF/Hogan designs.

Do you mean Hogan?

Yes, sorry.  I did mean Hogan, and corrected the response.  Thanks!

FWIW The GA stands for "Gnats Ass"

Looks like Troy also makes rails for 308 AR's as well, not sure if that was mentioned

This section needs help!

Caveats

RRA LAR-8 and Bushmaster BAR-10 308 (pre-2010) caveat: these guns have a proprietary design with proprietary buffers.  RRA goes out of their way to state this on their website.  The design started life as the Bushmaster BAR-10 and the design was sold to RRA, who have continued marketing it as the LAR-8 it after making small changes.  Bushmaster has been selling rebadged DPMS LR-308's as the Bushmaster ORC and Hunter 308 lines since 2010, and this caveat does not apply to those rifles.  Bushmaster BAR-10 and RRA LAR-8 actions have a longer stroke, and thus a shorter buffer compared to every other 308 AR out there. Take a look at this picture of an LAR-8, the receivers are a bit odd (long) in proportion to most 308 AR's. The reason is the proprietary bolt catch/release, which is positioned similarly to an ACR or Beretta ARX.  Therefore nothing in this section is applicable to these rifles, however Slash does sell buffers for these rifles on his website.

DPMS GII LR-308 caveat: these guns have a new proprietary design, and according to DPMS their carbine buffer and spring do not interchange with the gen one rifles.  I assume that none of this information pertains to the GII rifles.  It could be that they have gone to a system that splits the difference between ArmaLite and DPMS in order to achieve a system that is 100% proprietary in nature, but that's just conjecture on my part.

HK MR762/HK417 caveat: The receiver extension on these rifles is much larger in diameter and completely different and incompatible with all aftermarket stocks because you suck and HK hates you.

Action length 308 vs. 5.56

The first thing you need to know is that AR-10 and 308 AR rifles have a longer action length than AR-15 rifles.  The actual action length isn't super important (and will vary even between rifles of the same make and model due to variations in the way the receiver and receiver extension are threaded) but it is important to know that it is around 3/4" longer than an AR-15 action.  This means that the BCG is moving an additional 3/4" into the stock, the charging handle is moving an additional 3/4" to the rear, and for these reasons you cannot swap an AR-15 stock, buffer and action spring system wholesale to a 308 rifle.  Many AR-15 parts can be used with 308 rifles when combined with the correct 308 specific components.

Rifle stocks

Rifle stocks for AR-10/308AR's are by and large the same as AR-15 rifle stocks.  Due to the longer action length, a stock with a cheek riser that works on an AR-15 may interfere with a 308 AR's charging handle.  Magpul sells a version of their PRS for 308 AR's specifically to address this issue, however the standard AR15 PRS can be modified by cutting the cheek riser, and I assume other stocks with adjustable comb height could be similarly modified.

Rifle buffers for 308 rifle stocks are not the same as AR-15 components, they are 308-specific. Standard(ish) 308 rifle buffers are slightly heavier and about 3/4" shorter than the AR-15 rifle buffer to accommodate the longer action stroke.  

ArmaLite EA1090 - Listed as 5.1875", 5.4 ounces
DMPS 308-BS-11 - Listed as 5.25", 5.4112 ounces
Slash Heavy Buffer - Listed as 5.200", 10.0 ounces.

Action springs for 308 rifle stocks are also not the same as AR-15 components.  They are higher rate springs.  Slash recommends the ArmaLite part FWIW.

ArmaLite EA1095
DPMS 308-BS-10B
TUBB ARBUFSR
JP JPS-OSR.308
JP JPSCS-10 - proprietary captured system with springs, must use included spacer, alternative springs available as JPSCS-PACK10
JP JPSCS-10K - as above with alternative springs, must use included spacer.

Carbine stocks

Here's where things get muddy.  There are two competing standards for carbine stock systems in 308 AR rifles, and it goes beyond the commercial/mil-spec dichotomy found in AR-15 carbine stock systems.

The first system, which I will refer to as the ArmaLite AR-10 style carbine stock system or "ArmaLite style system" for short, uses AR-15 carbine buffers.  As stated earlier, the stroke of a 308 AR's action (and thus the stroke of the BCG inside the receiver extension) is around 3/4" longer than in an AR-15, and so for this system there are 308-specific receiver extensions that are around 7 3/4" long internally vs. 7" internally on the AR-15 variety.

The second system, which I will refer to as the DPMS LR-308 style carbine stock system or "DMPS style system" for short, uses AR-15 carbine receiver extensions.  Again, due to the longer stroke of the 308 AR action, a 308-specific buffer is used that is around 3/4" shorter than an AR-15 carbine buffer.

This picture illustrates the difference between ArmaLite AR-10 style carbine receiver extensions and the AR-15 carbine receiver extension used in the DPMS style system:



This picture illustrates the difference between DPMS LR-308 style carbine buffers and the AR-15 carbine buffer used in the ArmaLite style system:



ArmaLite AR-10 style carbine stock system

ArmaLite and several other manufacturers (complete list at the bottom of this section) utilize an AR-15 carbine buffer in conjunction with a 308-specific action spring and receiver extension.   You can use any carbine stock that matches the OD of your tube (commercial vs. mil-spec) however see the notes below on which setups will either not fully collapse or over collapse.

The buffer ArmaLite uses is identical to an AR-15 H3 buffer.  It contains three tungsten weights and weighs 5.4 ounces.  Other manufacturers that use this system style may use differently weighted buffers from standard carbine all the way through H3.  If you need to go heavier than an H3, the AR-15 buffers listed on Slash's site will work and he recommends the XH.

Action springs are 308-specific and are of a higher rate than AR-15 carbine springs.

ArmaLite EA1095 - This is the same as for the ArmaLite rifle stock and is what I use in my carbine stock.
TUBB ARBUFSR
Sprinco "RED" Spring

Receiver extensions are 308-specific and are about 3/4" longer than AR-15 receiver extensions (see pic above.)  Depending on the receiver extension used, you can fully collapse elongated stocks such as the VLTOR Emod and MagPul ACS/ACS-L/STR stocks.  On the flip side, if you use a stock with no back (visible hole in the rear of the stock as with a mil-spec collapsible stock) it is possible to over collapse a standard length stock on an extension that allows an elongated stock to fully collapse.

Several manufacturers offer the 308-specific receiver extension for sale separately:

VLTOR RE-A5 - mil-spec OD, allows elongated stocks to fully collapse.
VLTOR RE-10/A5SR - mil-spec OD, will not allow elongated stocks to fully collapse or standard stocks to over collapse.
ArmaLite 10207025 - mil-spec OD, will not allow elongated stocks to fully collapse or standard stocks to over collapse.
POF 00517 Buffer Tube, Anti-Tilt (7-Position) - mil-spec OD, allows elongated stocks to fully collapse.  Anti-tilt feature for op-rod guns.
LaRue LT629-15C for 7.62 - Select the 7.62 option, mil-spec OD, will not allow elongated stocks to fully collapse or a standard stock to over collapse.

Incidentally, the non-VLTOR tubes will probably work with VLTOR A5 buffers in an AR-15.  I have not verified this, but I don't know why it wouldn't work.  Could be of interest to folks who want an anti-tilt receiver extension with an A5 buffer in an op-rod AR-15 - POF may have you covered.

Stocks are standard AR-15, and all of the receiver extensions I have found utilize the mil-spec diameter, so you'd have to use a mil-spec stock.  As mentioned above, if you choose the right receiver extension you can fully collapse an elongated stock such as the VLTOR EMOD and MagPul ACS/ACS-L/STR.  If you wish to use a stock with an open rear, make sure to choose a receiver extension that will not let you over-collapse the stock.

Complete stock kits are available from additional manufacturers that do not offer the parts individually:

KAC offers the "M110 Collapsible Stock Kit," part number 25951.  It's not listed on their website but you can purchase it through their dealer network, e.g. here.  This kit appears unique in that it utilizes a ten position receiver extension, whereas the other receiver extensions available are either seven or six position.  It appears to allow elongated stocks to fully collapse and comes with the MagPul ACS.

LMT offers a few different kits:

LMT L7LA2CT - I can only assume this is mil-spec OD since LMT's SOPMOD stock is mil-spec, the stock is not long enough to fully collapse.
LMT L7LA2C - As above only in black.
LMT DMR308-KIT - same guts as above but with LMT's DMR stock that resembles a MagPul PRS.  It slips on over the carbine style receiver extension whereas the PRS utilizes a rifle receiver extension.

The following rifle lines utilize the ArmaLite style system, albeit with their own flavor of buffer weights and springs:

ArmaLite AR-10
KAC M110 (when equipped with above-referenced kit)
KAC 16” SR25 EC and ECC, see here.)
LMT LM308
POF mfg Oct 2012 or later, see note at bottom of page here.
S&W M&P10 - known to use smaller gas ports and lighter buffers.  Rifle stock systems use the carbine buffer/spring and a spacer.
LaRue 7.62
PSA PA-10*
Sig 716 - certain models use the DPMS style system instead.
Ruger SR-762

* Apparently many if not all of the first PSA PA-10 rifles to ship came with the ArmaLite length tube, but the DPMS shorty buffer.  This caused the shoulder on the BCG to slam into the lower receiver and receiver extension causing damage.  Apparently moving forward, they are using the correct AR-15 length buffer and if you have one of the DPMS shorty buffers, you NEED to call them and get a replacement.  Your buffer spring may also be incorrect, count the coils and measure the length, should be about a foot long with 27 coils.  Because of this fuckery I can't recommend buying PSA parts, although their receiver extension might be an option in the future if you can get them to sell it by itself for less than what the other options on the market cost.

DPMS LR-308 style carbine stock system

DPMS and several other manufactures (complete list at bottom of this section) utilize an AR-15 receiver extension in conjunction with a 308-specific buffer and action spring.  You can use any carbine stock that matches the OD of your tube (commercial vs. mil-spec.)

The buffer DPMS uses looks like a cut-down AR-15 carbine buffer.  It is around 3/4" shorter.  You can see a comparison pic above.

There are a few options for buffers:

DPMS 308-CS-10B - this is the standard DPMS buffer.
Slash CAR-10 buffers - Available in 5.5oz and XH 6.5oz.  Slash recommends his proprietary spring for use with these.
Buffer Technologies KynSHOT KSRB5004 - Hydraulic recoil damper.
JP JPSCS-10 - proprietary captured system with springs, alternative springs available as JPSCS-PACK10
JP JPSCS-10K - as above with alternative springs.

Other companies may make something very similar to the DPMS buffer, but they've gotten pretty generic by now similar to mil-spec AR-15 buffers.

Action springs are specific to the DPMS LR-308 style system.  Springs that work in the ArmaLite AR-10 style system will not work with the DPMS style system.

DPMS 308-CS-10A
JP JPS-OSC.308
JP JPSCS-10 - proprietary captured system with buffer weights, alternative springs available as JPSCS-PACK10
JP JPSCS-10K - as above with alternative springs.
Slash .308 CARBINE Buffer Spring - Custom
Sprinco "ORANGE" Spring

Any AR-15 carbine receiver extension will work with the above components, commercial or mil-spec.  If you want to run a MagPul UBR on your rifle, they're the only way to go.

The following rifle lines utilize the DPMS style system, albeit with their own flavor of buffer weights and springs:

DPMS LR-308 Gen 1 Rifles
Bushmaster 2010+
Remington
POF prior to Oct 2012
Black Rain Ordinance
CMMG
Colt 901
Fulton Armory FAR-308
LWRC REPR
Wilson Combat .308
JP LRP-07
SIG 716 - certain models use the ArmaLite style system instead.

What should the gas hole size be in a DPMS 20" barrel when using a standard A2 style stock and buffer.

Pit together an upper with the 20" barrel from Numric gun parts and my rifle is single shot and wont lock open on empty mag.

It works fine with my factory DPMS 16" upper.

Any ideas?

Hey mods. If this is the wrong place for this please move it.

Thanks

ETA: Re aligned gas block and problem solved.

Should try resizing 50bmg that's been shot out of an M2.

I'm assuming it's a .308.

It could be a rough chamber. Quite a lot of the DPMS barrels have rough chambers.

This FAQ has been very useful over the years. (Thanks Forest!)  

Perhaps you can add Sig Sauer to the list of "AR10" 308 platform rifles with their 716 series.

Do AR-15 Free Float Barrel Nuts/Handguards fit on AR-10 Upper Recievers?

No.

Blackhole Weaponry also makes quality barrels in most calibers

Are the upper receiver threads the same for AR10 and DPMS ?