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Discussion Starter #1
Fairly new into the firearm scene less than a year with firearm experience. I'm on my 2nd AR build (first build was 10.5in 556 build) My first build was fun and I was very happy with it that I wanted to build another. Building a 9mm glock fed magwell to compliment my newly bought glock 19.

So far I'm working on my lower (side folding AR platform 9mm glock fed). I just recently came back from the gunshop to purchase my brace, buffer tube, and spring (my 80% lower already came with a buffer, so I figured that there would be no reason to buy another buffer). Since I'm still new to the game I asked for help from the employee working there, he was very helpful and showed me to the parts I asked for. I saw a strike industries brace that caught my eye, so I picked that up, then I asked the worker what kind of tube can I get to fit this as it does not look like a standard mil-spec tube....

He then hands me a tube "SB Tactical OPNT Open Pistol Buffer Tube" and says this will work. I went with whatever he gave me, not looking at what it was (figured he knew what he was giving me since he works there).

So as I get home, I noticed that there was a giant hole at the end of my tube. As for what I knew from my previous AR build, there shouldn't be a hole at the end, where does my buffer spring and buffer go? If I put it in wouldn't it just come out the other end?

Sorry if the question seems stupid, but someone please help. Did I buy the wrong tube? Or is this something new/different that i'm not getting because its an AR 9mm build?
 

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It's a proprietary tube to work with their brace. It's open ended because it's non functional. It's designed to be used with a blowback/piston system.
 

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I've been thinking about your description of what you want to build. I have a few questions for you. Have you thought this build all the way through? For a folding stock, what adapter are you planning on using? What gas system are you planning on using, DI or piston? With that tube and brace, you're going to need to go with a bufferless upper build. The most common is the BRN 180 from Brownells.
 

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I'm building an 80% 9mm Glock mag lower, I'm using a 6 position stock on mine. I'm still looking for parts for my upper. The 9mm AR uses a heavy buffer & spring. The is no gas system on a 9mm AR, the barrel has no gas hole. I'm not familiar with what a folding stock requires, mine will have a 16" barrel. I'm curious about your build now, I'll be watching for guys who know AR's to respond.
 

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SBE, in your case, you are looking at a blow back system where the bolt doesn't lock up, but depends on the buffer spring to return the bolt to battery and keep it there. Chamber pressure will move the bolt rearward and extract the case. In Jacks situation with that buffer tube he has no spring to return the bolt to battery so he will need a bufferless system, such as the BRN and a few others, that have return springs in the upper receiver and a gas piston system.
That said, I am no expert, that's just my understanding. I haver never built a pistol version, so take it for what it's worth.
 

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Discussion Starter #6
I've been thinking about your description of what you want to build. I have a few questions for you. Have you thought this build all the way through? For a folding stock, what adapter are you planning on using? What gas system are you planning on using, DI or piston? With that tube and brace, you're going to need to go with a bufferless upper build. The most common is the BRN 180 from Brownells.
Not sure what you mean by "thought it all the way through" I mean I knew what I wanted at first, but when I went to the gun shop "Strike Industries Brace" caught my eye and wanted to go with that.

As for the tube, I didn't know what to buy to work with the brace, but the worker at the gun shop handed me that tube with the hole at the end of it and said it would work.

As for a bufferless build, I didn't even know that it was possible (I assumed add AR platforms needed a buffer, only taking experience of what I built in the past).

I'm not running an adapter on my folding stock. I purchased an embeded folding brace on my New Frontier lower.

Gas system? As far as I know 9mm don't have a gas system (correct me if I'm wrong). Again I'm also still a newb to all this stuff, but hope my answers to your questions were of any help.
 

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Jack,
Actually some 9mm do have a gas system. I looked at that tube on their website, it shows that it's about 2" shorter than an average tube. But I couldn't see the back end of it. Is it open the entire diameter or is there a lip that would retain the buffer spring? That's where I'm getting hung up. If it has a lip and they gave you a shorter spring, then most of what I said goes out the window. You would be able to set it up as a blow back system. I will say that the colding brace is still throwing me off. I'll go back and look at the brace.
 

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Discussion Starter #8
Jack,
Actually some 9mm do have a gas system. I looked at that tube on their website, it shows that it's about 2" shorter than an average tube. But I couldn't see the back end of it. Is it open the entire diameter or is there a lip that would retain the buffer spring? That's where I'm getting hung up. If it has a lip and they gave you a shorter spring, then most of what I said goes out the window. You would be able to set it up as a blow back system. I will say that the colding brace is still throwing me off. I'll go back and look at the brace.
I attached a picture of the the tube looks like at the end of it. There is no lip just a straight hole'd tube.

The brace/stock isn't configured as folding (Strike Industries Brace, its just alternative to shockwave blade brace). Also, it's my lower receiver that has it built in, that makes it a side folding part.

tube.PNG
 

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I don't see how that tube is going to hold a buffer spring. Unless I am missing something. Maybe we can get @zant to show up. He's the AR wizard.
 

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I don't see how that tube is going to hold a buffer spring. Unless I am missing something. Maybe we can get @zant to show up. He's the AR wizard.
That was exactly my point. Wondering why the employee at the gunshop recommended that to me when I bought the brace. And what exactly is this used for, if ARs need a buffer, spring set up? Maybe understanding what it's actually used for will help understand why he recommended it in the first place. Maybe I didn't give him enough information on what I was doing exactly to my build.

Thanks for your help howlnmad! More info is also appreciated
 

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I don't see how that tube is going to hold a buffer spring. Unless I am missing something. Maybe we can get @zant to show up. He's the AR wizard.
Nope-Homey don't do 9mm or any other pistol calibers in the AR platform...it was'nt designed for it or the buffer/no buffer used in a such systems.I stick with rifle calibers in a AR.....
 
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