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Newbie looking for advise on .308 build


Former 11H
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Posted (edited)

Here are two screenshots of the tube. Maybe they mean it’s for a 6” buffer?

i don’t have to buy it from Aero Precision. If you can suggest something else , I’m game.
 

F61D2CCD-D6EC-4471-91CA-F1563DC41542.png

E8849544-0F9C-4111-8FA3-FD04B72799A0.png

Edited by Former 11H
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6 hours ago, Former 11H said:

Here are two screenshots of the tube. Maybe they mean it’s for a 6” buffer?

i don’t have to buy it from Aero Precision. If you can suggest something else , I’m game.
 

F61D2CCD-D6EC-4471-91CA-F1563DC41542.png

E8849544-0F9C-4111-8FA3-FD04B72799A0.png

That is a rifle length buffer tube.  It uses a 5.9 inch rifle buffer in an AR15.  In a 308AR, the buffer is 5.2 inches.  Like @98Z5Vsaid earlier, the rifle length buffer tube cannot use a carbine/collapsible stock.  You must have a rifle stock.  With your goal of maximum felt recoil reduction, the rifle buffer system with the XH buffer linked earlier will be your best bet.

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98Z5V
Can you help me work backwards from the heavy buffer’s 10oz. buffer and spring to determine what tube will accommodate them and work with my 80% Arms DPMS lower that is matched to my Aero Precision M5 upper(not enhanced)?
Once I know what tube to get, I can find an appropriate fixed rifle stock. 
Thanks
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40 minutes ago, Former 11H said:
98Z5V
Can you help me work backwards from the heavy buffer’s 10oz. buffer and spring to determine what tube will accommodate them and work with my 80% Arms DPMS lower that is matched to my Aero Precision M5 upper(not enhanced)?
Once I know what tube to get, I can find an appropriate fixed rifle stock. 
Thanks

Easy, man - ALL rifle receiver extensions, just like the one that you linked above, are 9 11/16" internal depth.  All of them.  Some places say "A1" and some places say "A2~!" - those A1~A2 differences are 100% external to the Rifle Receiver Extension.  Not internal.  There's hardly a company out there that fuks up the Rifle Receiver Extension, so trust what you linked - buy the AP that you linked.  Get it.  Rifle Receiver Extensions measure 9 11/16" internal depth.

Get the buffer I linked - get that one.  Combine those two parts with the Armalite EA-1095 recoil spring - and heavybuffers.com will send you that very spring, if you ask Clint @ Heavybuffers.com to send it to you with your buffer - he believes in them, and knows they work.  He stocks them, in his shop. 

If, for some reason, you can't find the Armalite EA-1095 recoil spring, or Clint @ Heavybuffers is out of them - then the next best choice for the proper spring is Sprinco, and buy their Red Spring.  That's the most-closest to an Armalite EA-1095 on the planet.

THAT will give you a solid recoil system that will not fail you.  If you have issues after that - it will not be from your recoil system.  Or, I'll buy all your parts from you that you had to buy, and I'll use them.  Full-rip retail, plus shipping-twice, straight to me - whatever it cost you in the whole process.

Many guys here try to duplicate my "money-back guarantee," but I'll tell you this - I've never had to pay anyone here for parts that didn't work.  What I recommend works.

You get that recoil system that I've lined out.  After that, we fix your gas system.  Your gas port is too small, I already know that, and know what it needs to be.  You get the barrel in-hand, and we check the gas tube for the proper protrusion into the upper receiver - if it's screwed, I'll tell you what gas tube you need to fix that issue.

After that, you'll have a running gun, at the lightest recoil that you can possibly have, and it will eat ANY commercial ammo that you throw at it. 

I stand by that.  :thumbup:

Edited by 98Z5V
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FWIW - there is not, and never has been, a 6" buffer, ever.  Not for AR15, not for .308AR, for nothing.  Ever. Not even Rock River Arms.

Aero Precision seriously fukked that up when they listed that on their website.  Badly.

They can contact me via PM or right here publicly, if they want to discuss that erroneous listing.  I'll debate them, and let them know the errors of their website-guy's ways.

That animal doesn't exist.

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Stoner must have been an incredible engineer and a very, very, patient man. The system is quite simple in principle, but the devil is in the details!

I have the upper, gas tube and and block in hand. Barrel and BCG arrive Saturday. 
The barrel shroud will have to wait a bit as money has been going out faster than it’s coming in. I’ll buy the buffer, spring and tube next. 
I should be able to dry fit everything together to check the position of the tube in the upper, shouldn’t I?
I would like to drill out the barrel to its new specs as well. Gotta number?
BTW, I’m still waiting for the lower jig from 5D Tactical, ordered nearly 5weeks ago when it was listed as “in stock”. Apparently, they had some manufacturing issues and a ton of orders. I’m not going to buy a small router until I have the jig. I have a big router but that won’t work for this. If they fail to deliver, I’ll be forced to buy a serialized lower from AP. 
That defeats the purpose of this particular rifle but I have to finish it either way.
Aero Precision’s website guy should have a rubber band wrapped around his nuts. 
They do that to cows or bulls to castrate them. Eventually, they just fall off. 
That is a very generous offer but I can see this isn’t your first rodeo and l’m sure I won’t be sending you any parts. 
Thanks again. 
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2 hours ago, Armed Eye Doc said:

He wasn't old enough to know the difference

He does, don't turn your back on him and watch your feet when when your close....... I've been on my arse looking one in the eye, he remembered and Grandpa laughed his arse off.

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16 minutes ago, jtallen83 said:

He does, don't turn your back on him and watch your feet when when your close....... I've been on my arse looking one in the eye, he remembered and Grandpa laughed his arse off.

Thanks for the tip.  He has always been a little skittish around us.  I'll keep a watch out for any sudden movements from him.

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14 hours ago, Former 11H said:

I should be able to dry fit everything together to check the position of the tube in the upper, shouldn’t I?

Absolutely.  Go ahead and pin the gas tube in the gas block - you'll never have to undo it (unless it's not long enough).  Slide that block on the barrel until it seats on the shoulder, and see how far the gas tube protrudes into the upper receiver.  If it's perfect, the tube will end in the very center of the cam pin cutout in the upper.  If it's too short, you'll know right away.  Here's what right looks like:

P1060637.JPG

 

EDIT - Gas port info...   18" midlength gas barrels (in .308 Win chambering) that are using a 0.750" gas block journal size need a gas port range of 0.080"~0.085" to run properly.  I've skipped the lower part of that and gone straight to 0.085" on a few, and they eat anything I feed them.  Even junk ammo.  For a 16" barrel, you have 2" less dwell time, so you'll need to up your gas port diameter.  I'd start right away with 0.085", knowing that you might have to go up to 0.090" in the long run.  Since you're using an adjustable gas block, there is absolutely zero penalty in going straight to 0.090" in the first place - because if it's slightly large, you can dial the gas back down with that block adjustment.   Verify your gas block journal diameter of 0.750" before drilling anything - I know that's what it is, but verify that number, and get back in here right away of it's different, for some reason.  Gas block journal diameter directly affects proper gas port diameter.

Hope that makes sense.  :thumbup:

Edited by 98Z5V
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Thanks for that. Crystal clear. 
I’ll verify the gas block journal size and let you know if it’s not .750”. If it is correct, I’ll drill out the barrel’s port to .090”. I’ll also check the gas tube length this weekend if the barrel comes Saturday. 
I’ve been hounding 5D Tactical weekly to send the jig and tooling. Finally shipped, also due in on Saturday!
If the gas block journal isn’t as advertised, I’ll have to add another band to that guys nuts!
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Hi guys, The barrel and BCG arrived today. I measured the journal on the barrel where the gas block mounts. It is indeed 0.750”

I also measured the gas port in the barrel as best I could with a pair of digital calipers. 

It is 0.0745” If I use a #43 drill at .0890” (2.26mm), will that be big enough?

Obviously, I will be removing the finish on the ID of the hole.

In your experience, has that ever caused corrosion and reduced the gas pressure over time?

I will dry fit the barrel, upper, gas block and gas tube tomorrow to check for proper tube length.

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1 hour ago, Former 11H said:

If I use a #43 drill at .0890” (2.26mm), will that be big enough?

Run it.  Go slow, slow speed on the drill, very light pressure.  Use lube, WD-40 if you have nothing else.  Let the bit do the work - let the bit eat.  That's what it does.  Shove a 1/4" wooden dowel down the barrel if the "breaking through" makes you nervous.  It's really not a big deal to punch up a gas port.  I've done it in camp, during a shoot, in personal conditions that I'd rather not explain - just to get a gun running.  It's easy, and it works.  :thumbup:

The pilot hole to drill through is already there, right in front of you.  It's really hard to mess this up.

Edited by 98Z5V
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Sounds good. I have drilling and tapping fluid. I’ve drilled thousands of holes in every type and thickness of material you can imagine  Not nervous. I suspect the hole is positioned so that it is located in one of the grooves inside the barrel, not on a land. 

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As 98 said, go slow.  A drill press is the perfect tool for drilling out a gas port.  Just cradle the barrel so it doesn't wobble, a drop of oil in the port, maybe one on the drill bit tip and gently press the bit through.  It can't go crooked because you already have a perfect guide hole.  Going slow minimizes metal breaking as the bit finishes the hole and what might hinge into the barrel is gone as soon as you fire the first bullet through it. 

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I “pinned” the gas block and tube with a micro screwdriver to dry fit the barrel, block, tube and upper. The tube protrudes into the upper just a speck passed the center of the cam pin cutout. Looks identical to the photo posted above. 

I put a strand of copper wire through the gas port in the barrel. After about 5 minutes of studying inside the barrel with a light at the other end, I was able to determine that the hole IS in a groove, not through a land. No idea if that was good engineering or just good luck.

A7305F45-FED9-4093-A17A-177A4BB1A27B.jpeg

FD6705D8-7F37-474A-9346-72B712CDEF8A.jpeg

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18 hours ago, Albroswift said:

That's giving someone a lot of credit!

 

Exactly - that's pure luck on a barrel...  :laffs:

14 hours ago, Former 11H said:

After about 5 minutes of studying inside the barrel with a light at the other end, I was able to determine that the hole IS in a groove, not through a land. No idea if that was good engineering or just good luck.

That was luck, no other way around it.  At any rate - that's awesome! 

Your gas tube protrusion is absolutely perfect - run with scissors on that one.  It doesn't get any better than that, right there.  :thumbup:

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