AR10/.308 AR Build knowledge thread.

[polydeuces]

While waiting for some parts to come in got to think - probably need some specific AR308 tools. I know from experience having the right gear makes all the difference.

From the top of my head - Barrel nut, different from AR15, so I'd need specific wrench for that.
Are there any specific upper action blocks that can be recommended?

Besides that anything else that should be considered?

[LRRPF52]

So you are saying there's a chance. Rather it sounds like the AR901-16S can be configured by the user with a preferred handguard and barrel. I'm assuming if it has "the same" barrel extension as the SR-25/DPMS then it's compatible with this type of barrel. For choosing a different handguard, the receiver height is usually the important measurement when it comes to the semi-308 market. I wonder if the AR901-16S is comparable to the DPMS Gen I or II (or worse, neither)?

The reason I'm so intrigued is that the 901 has in my estimation received favorable reviews and exhibited decent accuracy. If the handguard can be replaced with current options (my gripe with the monolithic model) on the market and the barrel could be swapped for those requiring more accuracy potential, then an MSRP of ~$1400 from Colt seems very appealing. That price and product is appealing at least until this market evolves and/or stabilizes in terms of specifications.

There are now 3 different heights of rail for the large frame DPMS guns:

LR-308 with SR-25 rail height, confusingly called the "low-profile" upper because there is no FA or ejection port door
AP4, which went away from SR-25 and ArmaLite Inc. rail height by lowering it.
GII, which is AR15 height.

[Plasman]

There are now 3 different heights of rail for the large frame DPMS guns:

LR-308 with SR-25 rail height, confusingly called the "low-profile" upper because there is no FA or ejection port door
AP4, which went away from SR-25 and ArmaLite Inc. rail height by lowering it.
GII, which is AR15 height.

There's also a fourth "super high" rail on the LR-308B that only this rail aligns with.

[Christopher]

2 Questions:

1. On a 18" barrel does it matter if i go with a mid-length gas system or should i go with a rifle length gas system?

2. Do i need an adjustable gas block, or will a regular gas block work just fine?

Thanks.

[hotrodder636]

I'm in this as well.. I'm just waiting for the Black Friday sale's to hit. At the moment, I'm thinking I'll take the route of a cheap (PSA) lightweight carry handle carbine. Just something to get into the game with and play a little. Interesting that PSA seems to compete with themselves with the PTAC line. I've had good luck with the PSA premium line and will probably stay there for this build..

If you get emails from Aero, during November they have been having a "deal of the day" which led to a very we'll discounted price on 2 upper/lower sets for me. Unfortunately I did miss the deal on the uppers...but the end price was still good. I imagine this coming week will also have some good prices.

[hotrodder636]

Here is some useful information for the Aero Precision M5 308 Builders. These notes were compiled after speaking to Angela at Aero Precision and also with Alan from SpringCo. This is a work in progress (both these notes and my build) so please help me correct any errors.

Lower Receiver

The specific 308 parts for the Aero Precision M5 lower are:

• Pivot Pin - AP M5 specific
• Takedown Pin - AP M5 specific
• Bolt Catch - DPMS 308 pattern
• Bolt Catch Threaded Screw (included with the M5 lower, needs 1/16" allen wrench)
• Buffer Spring - use DPMS 308 pattern carbine spring or SpringCo Orange
• Carbine Buffer - use DPMS 308 pattern carbine buffer (2.5")

There is no trigger guard required, so the remaining lower parts from any Mil-Spec AR-15 LPK would be:

• Receiver Extension
• Buffer Retainer and Buffer Retainer Spring
• Takedown Pin Detent Pin and Takedown Pin Spring
• Pivot Pin Detent and Pivot Pin Spring
• Bolt Catch Buffer and Bolt Catch Spring
• Trigger Assembly (Hammer, Trigger, Disconnector, Disconnector Spring, Trigger Spring, Hammer Spring, Trigger Pin, Hammer Pin)
• Safety Selector
• Selector Detent and Selector Spring
• Magazine Catch, Magazine Catch Spring, Magazine Catch Button
• Pistol Grip, Pistol Grip Screw (and washer)
• Mil-Spec Stock

BTW, I suggested again that they package up an M5 308 Lower Parts Kit that is "minus" the trigger group and pistol grip. Hopefully we'll see one soon.

Upper Receiver

The specific 308 parts for the Aero Precision M5 upper are:

• Ejection Port Cover Door - DPMS 308 pattern
• Ejection Port Cover Rod - DPMS 308 pattern
• 308 Barrel - DPMS 308 pattern
• 308 Barrel Nut - DPMS 308 pattern
• 308 Charging Handle - DPMS 308 pattern
• 308 Bolt Carrier Group - DPMS 308 pattern
• 308 Flash Hider - 5/8x24" TPI
• 308 Crush Washer

The remaining upper parts from any Mil-Spec AR-15 can be used:

• Ejection Port Cover Spring
• Gas Tube (appropriate length for barrel)
• Gas Block (appropriate size for barrel)
• Forward Assist Assembly Kit

This is excellent, thank you!

[Malig8r]

If you get emails from Aero, during November they have been having a "deal of the day" which led to a very we'll discounted price on 2 upper/lower sets for me. Unfortunately I did miss the deal on the uppers...but the end price was still good. I imagine this coming week will also have some good prices.

My FDE set cost $260 and the Black anodized set was $240 due to these daily deal emails. Eagerly waiting for the daily deal on the BCG!

[LRRPF52]

There's also a fourth "super high" rail on the LR-308B that only this rail aligns with.

That is the 1st LR-308 "lo-pro" upper, commonly referred to as the "high profile" receiver height. DPMS introduced it with the LR-308. Then came the AP4, and now the GII.

I remember when it first hit distributors, so I have more or less a chronological memory of what has been introduced in the AR10 market since the introduction of the KAC SR-25 in 1993. I pay very close attention to what's new, try to stop by all the relevant booths at SHOT, review other media outlet reviews on developments with the AR10, and it has become increasingly difficult to keep track of all the rifles and their variations. This year has seen an explosion of AR10 products, on top of several past years of new AR10 offerings. It's been steady since the expiration of the Clinton AWB in 2004.

[Christopher]

2 Questions:

1. On a 18" barrel does it matter if i go with a mid-length gas system or should i go with a rifle length gas system?

2. Do i need an adjustable gas block, or will a regular gas block work just fine?

Thanks.

Anyone?

[LRRPF52]

You can do either, but I personally would go RLGS 18" with a .308 Win. Look at one of the most reliable configurations on the market, the SR25 carbines.

They use 16" pipes with RLGS, but they also know what they're doing when it comes to the gas system.

Your ammunition, port diameter, and how well the gas is sealed will determine whether or not you need adjustable gas.