AR-308 Building help needed

[850guns]

So my AR-15 projects are wrapping up. And I was doing parts inventory and fitment checks on my AR-308 projects. I have been slowly collecting parts and doing research for well over a year, (probably over 2 years)
My plans (for now) are to build 3 firearms, in 3 different barrel lengths. And do some testing and learn the advantages and disadvantages of the different OAL. Enough about that!

So the reason for my posting this thread is my 308 BCG, I bought year(s) ago, don't remember where.
I nearly posted a pic in that new ar10 bolt id thread.
During mock up with 3 different barrels, I couldn't get the bolt to go into full battery. After pulling the barrel and aligning the bolt up by hand, the spline on the back of the extractor is too wide to engage the splines on the barrel.
So then I start wondering if it was a different caliber bolt, so i took a 308 casing to check fitment and noticed the bolt face has dual electors. The case was hard to snap in place, but it finally did. My other 308 is actually an AR-10 and these are LR-308 dpms pattern, not sure if the bolts are compatible as i don't have it with me for reference. But I would like to know.

So, I am thinking easy fix. Either replace the extractor and upgrade the spring while I am there, or file down the spline to fit. Either way I'll probably remove the extractor. But now, I discover one of the 2 ejectors has decided to stay depressed! I can't win for loosing!
Now I have to figure out how to "fix" my new parts. Ugh!

 

[Raven]

Gen 1 DPMS had only one, Gen2 has two, and they're not backwards compatible

 

[Raven]

And DPMS stopped making Gen1 a while ago, and is now bankrupt.

 

[850guns]

Gen 1 DPMS had only one, Gen2 has two, and they're not backwards compatible

Has 2? Types of bolts?

 

[Raven]

Ejectors. The Gen2 has two ejectors, and the Gen1 has only one ejector. And the Gen2 bolt with 2 ejectors is not backwards compatible in a Gen1 receiver/chamber

 

[Raven]

Oops, almost bankrupt

 

[IronBeard]

.308's are more proprietary, and not as interchangeable as much as AR-15 parts. Good luck.

 

[Rebel_Rider1969]

Yeah, don't whittle on the DPMS parts, I can use em. Ill get up with you when I get home.

 

[850guns]

My vice blocks and torsion rod came in yesterday. I am ready for for assembly!

 

[MARK1200]

My vice blocks and torsion rod came in yesterday. I am ready for for assembly!

Good for you!


Sent from my iPhone using Tapatalk Pro

 

[850guns]

So, my next question is about Gas Blocks. One of my barrels has one gas block dimple, but my gas block has 2 set screws. Will I be ok to just tighten the screws real good? Or should I add another dimple?

AND, my other two barrels have no dimple. Which is better, clamp on gas blocks or set screw gas blocks? Or does it matter?

Do I really need a dimple jig if I have a drill press and vise?

 

[Rebel_Rider1969]

It's amazing to me that more company's don't dimple the barrels for the gas blocks. 1 is great. None is ok. Just gotta get it centered. The spacing is about the thickness of a credit card off the shoulder of the barrel if it has one, where the gas block stops.

 

[Phantom006]

Reputable clamp type... or-
Dimple the barrel, follow up w/cold blue.Use a “Vibra-tite” tread locker, (non permanent)., on set screws. If you look through the set screw hole on the bottom of the gas block, you will see the gas port. With a quality caliper, measure this distance from front of GB and transfer to barrel. Set your jig and use a BALL END MILL In your press,and set depth .020”- .060”, so you don’t drill thru the barrel. Align off barrel shoulder.Most AR 10 (non ARMALITE) this measures out .032-.055”.

 

[850guns]

All my barrels are stainless, so I should be good to dimple without blueing.
Ordered my gas blocks yesterday, and my BCG's today!
Also I changed my mind on one of the handguards I have.
I ordered another, and it should be delivered tomorrow!

 

[Phantom006]

Like seeing people step out of their comfort zone..post pics..

 

[850guns]

My handguard came in.
And so did my BCG's!
AND they fit my barrel extensions!
(doing a happy dance)

 

[850guns]

So i assembled my "precision rifle" lower last night. Looks pretty good! CMC flat trigger, some stainless/nickel parts, some GI parts, and a Luth-AR precision stock (MBA-1?). I will assemble the 20" BHW barreled upper tonight if i have time. Wait, i just remembered that I don't have a dust cover...

 

[Rebel_Rider1969]

All my barrels are stainless, so I should be good to dimple without blueing.
Ordered my gas blocks yesterday, and my BCG's today!
Also I changed my mind on one of the handguards I have.
I ordered another, and it should be delivered tomorrow!

Handgurad lenght?? On the one your not going to use?

 

[850guns]

Handgurad lenght?? On the one your not going to use?

It's a 12" M-Lok. Funny thing is, my new 17" handguard was only available in raw aluminum. It came bead lasted, and looks crazy cool. Then I discovered I could get a bead blasted receiver set to match. And decided to try to build a raw firearm. All that to say, I'll probably keep the 12" to use with my 16" barrel. I was going to use my Aero M5E builders set with the 16. But the upper uses a dedicated handguard (E=Enhanced), so I guess I'll save that set for later. Oh, I thought I read you ordered a handguard for your 308 build?

 

[Rebel_Rider1969]

It's a 12" M-Lok. Funny thing is, my new 17" handguard was only available in raw aluminum. It came bead lasted, and looks crazy cool. Then I discovered I could get a bead blasted receiver set to match. And decided to try to build a raw firearm. All that to say, I'll probably keep the 12" to use with my 16" barrel. I was going to use my Aero M5E builders set with the 16. But the upper uses a dedicated handguard (E=Enhanced), so I guess I'll save that set for later. Oh, I thought I read you ordered a handguard for your 308 build?

I did, can't get it to index right guard screws on the nut. Don't want to put a hammer or cheater bar on it!! I'll figure it out.