Need some help building an AR: It's alive!!

So a DD BCG popped up on the EE today. I grabbed it since it was what I originally wanted. What do you guys think? Any advantage to DD BCG over the LMT with DD barrel other than satisfying my OCD?

Whew that was a lot of acronyms!
 
I'm gonna use the DD BCG so I've got the LMT for sale. Here's where I'm at:

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Just ordered my handguard and gas block. Just need a gas tube and I'm done! I was waiting for the new Aero Quantum M-lok handguards, but I'm impatient so I went with the enhanced keymod that Sask GW had in stock.

I haven't mounted my barrel yet. I had to modify my vise block to fit my upper. I hope I'm not going to have any big pressure points in there but it's very difficult to tell. It fits in there and feels solid...am I good to go? I was wondering if I should pad it with some sort of moldable material to spread the force out...idk.
 
That looks like the best way to go...but not a cheap tool and I already have the vise block. I called a local gunsmith to see about having it installed and the conversation went like this:

GS answers the phone: "Yes?"

Me: "Uh, hi... I need to have an AR-15 barrel mounted to an upper receiver. Is that something you do?"

GS: "You need an AR-15 barrel 'mounted'?? Okay. What are you building?"

Me: "An AR-15...."

Then some more awkward exchanges and told me he can't do it until August...
 
You're better off using a Geisselle reaction rod or KAC extension tool. I saw a good price on the KAC on OSTS.

I just looked at the tool on OSTS, says it's not for use on standard ar15s. That just a legal disclaimer, or will it really not work? Said it works on an SR15.
 
When it was originally released, it was advertised as being compatible with both the E3 and standard barrel extension.

I can now see that they are advertising otherwise.

GRR is the best bet for a standard extension then.
 
Installed my buffer tube this evening. What is supposed to prevent rotation of the buffer tube / buttstock? Just the tension by the castle nut? It seems like the tab on the end plate should be for this purpose, but there is not really a deep enough channel in the buffer tube...the threads are cleared, but the tab would just plow into the threads on the buffer tube?

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Okay so here's where I think the issue is.

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The tab does not extend fully into the recess in the buffer tube. In fact the tab will ride the threads of the buffer tube. I thought I might be able to shift the position of the end plate, but there is no play when it is fully seated on the receiver.

Is this typical? Or do I have a ####ty buffer tube set?
 
Anyone know where I can find some specs on what the end plate is supposed to be on a milspec buffer tube? Trying to check the inside diameter to the nub. Maybe the nub isn't long enough?
 
The end plate will not rotate because of the indent, once the castle nut is tightened there should be no way for it to rotate as the tab is too wide. Even if the tab is too small once the castle nut is tightened it should prevent any rotation of the tube. The end plates are the same for both Milspec and Commercial tubes. Your tube does seem to have alot of threads exposed. Is it screwed in all the way to the plunger?
 
Yeah, screwed in right up to the nub of the retaining plunger. This is what I'm working with:

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I can tighten the castle nut beyond hand tight and then I can easily rotate the butt stock to loosen it...
 
You're overthinking this. Use your castle but wrench and tighten that sucker up. I'd be surprised if you can rotate the buffer tube after that. There will be some thread exposed...at least there is on my 3 ARs.
 
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