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Hog Hunter

What are the differences between Ar-10 BCG and LR308 BCG?

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I have a Armalite AR-10A2 carbine that I acquired from an online auction a few months ago.  It didn't come with a magazine but the price was right and I have always wanted an AR-10.  (Second Hog gun) I finally got a mag and ammo which have been hard to get inexpensively. I load the mag and pull the charging handle and the BCG just rips across the top of the round not even moving it. Ah poop!  I pull it back again but slower and the BCG doesn't go far enough back for the bolt catch the round. About 1/4" from getting there. I did notice when I picked up the rifle that the BCG had been replaced.  The BCG is nickel boron and has forward assist which my AR-10 doesn't have.  Also I found out that the buffer spring was the rifle length not the carbine which my rifle is.  My guess is the BCG is not an AR-10A2 compatible and I need to get on that is. I wanted to confirm my suspension first and seek information.  I haven't found much information about the differences between all the AR-10 and ar308 variations to measure or identify mine. The only label i have is it has the letters MP stamped on the top of the bolt. Any help would be greatly appreciated. 

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What is the internal length of your receiver extension? What is the length of your buffer? Armalite uses the same spring for rifle/carbine systems. What does your buffer weigh?

 

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The tube length it 7-3/4". The buffer length is 3-1/4" and is 2.9oz.  The spring is 12-1/2" 39 coil. I thought that this was the riffle length and the Carbine length was 24.5 coil 9-1/2". Is that false?

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My guess is you buffer system is wrong, but @98Z5V will be along shortly to verify those measurements. Its generally looked down on....but ive read threads on other forums of people swapping between AR10 and DPMS carriers and everything functioning. 

Edited by blue109

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First. Welcome. Second, Armalite factory rifle? Of what vintage and exact model number? You may have an A or B pattern, big difference, one uses sr25 pattern mags the other uses traditional Armalite mags! That I’m guessing is the entire issue. 

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2 hours ago, Hog Hunter said:

The tube length it 7-3/4". The buffer length is 3-1/4" and is 2.9oz.  The spring is 12-1/2" 39 coil. I thought that this was the riffle length and the Carbine length was 24.5 coil 9-1/2". Is that false?

False! Your buffer is way too light. Springs from Armalite are the same for rifle and carbine, buffers are different sizes. 

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I found this information with in 308ar.com's website.

 

Armalite AR-10 Carbine

  • Armalite AR-10 Carbine Buffer Dimensions – 3 1/4″ Part Number EC0120

  • Armalite AR-10 Carbine Buffer Tube Dimensions – 7-5/8″ Part Number 10207025

  • Armalite AR-10 Carbine Spring Dimensions – Max 11-1/4″ Min 10-1/6″ Part Number EC0040

 

But then under: "Compatibility>> Armalite AR-10 Buffer system"

it states that the Spring dimensions are a 13-3/4".

Which is it? 

If 11-1/4" then my spring is too long. if it is 13-3/4" my spring is too short. Neither of these real salve the problem of the BCG being in the locked back position and the Bolt being over the round by 1-/2", and not behind it.

 

 

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49 minutes ago, edgecrusher said:

First. Welcome. Second, Armalite factory rifle? Of what vintage and exact model number? You may have an A or B pattern, big difference, one uses sr25 pattern mags the other uses traditional Armalite mags! That I’m guessing is the entire issue. 

Thank you for the greetings.  Mine is the "B" series.  Fixed carry handle and no forward assist and the BCG has forward assist grooves. The upper and lower are Armalite. The stock and grip are Rock River Arms. The BCG has never been fired.  There is no oil residue, scratches, or carbon on it.

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49 minutes ago, Hog Hunter said:

Neither of these real salve the problem of the BCG being in the locked back position and the Bolt being over the round by 1-/2", and not behind it.

 

10 minutes ago, Hog Hunter said:

20201001_184006.jpg

 

Is that as far rearward as the BCG will travel? That's not locked to the rear by the bolt catch....

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11 minutes ago, Matt.Cross said:

 

 

Is that as far rearward as the BCG will travel? That's not locked to the rear by the bolt catch....

Yes, unfortunately. It has to be the compatibility of the BCG that the previous (dirty word) owner put in it. The buffer is as im researching is for an ar-15. Im in the process of buy a new BCG, spring and buffer.  Any suggestions for these parts?

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Re measured the internal measurement of  the receiver extension and it is 7" not 7-3/4" as I previously mentioned. External measurement is 7-3/4".

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4 minutes ago, edgecrusher said:

Complete Armalite recoil system. They are available on the site. No luck copy and pasting sorry.
 

 

Should have measured the inside first.  Would have saved a lot of headache.  On the bright side. I don't have to buy a new BCG.

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7" internal depth is AR15/LR308 extension.  You need the 2.5" LR308 buffer for that extension

 

Or get the AR10/VLTOR A5 extension

Edited by blue109

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∆∆∆∆∆ that is the right tube,buffer and spring. Everything in 1 package. If the website says out of stock call them they will usually make you up a set.

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3 hours ago, Hog Hunter said:

Re measured the internal measurement of  the receiver extension and it is 7" not 7-3/4" as I previously mentioned. External measurement is 7-3/4".

I've read through this, and I was JUST ABOUT to ask you what the INTERNAL DEPTH of the Receiver Extension was.  NOT the external length measurement.

That thing is your major problem.  The buffer weight  that you listed is also a major problem - it need to be 5.4oz.  AR15 H3 Carbine buffer is 3.250" long, and weighs 5.4oz.  Armalite AR-10 Carbine buffer is 3.250" long, and weighs 5.4oz.  Strange how that works.

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3 hours ago, Hog Hunter said:

 On the bright side. I don't have to buy a new BCG.

There is a big thread here on BCG differences, between Armalite and DPMS-based.

 

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I wanted to thank everyone here for helping me work through my issues. As I realized that the problem was in fact the buffer system not working with the rest of my equipment and not the BCG. I have ordered a CAR-10 XH 6.5oz buffer from heavybuffer.com. This will be suppressed with thermal scope for hog hunting.  I have already installed the adjustable gas block, new Armalite keymod handguard and A.R.M.S 2A carry handle rail adapter. Next will be the brass catcher.  I don't want my steers eating brass.

This will be my number 2 gun or if I have friends hog hunt with me. My number one gun is a Stag arms Verminator chambered in 6.8 SPC.  Is talking about that round allowed on this site? It is a left handed gun as I'm a lefty. Its a great gun and round with Hornady GMX. With the thermal I can get 20 yards away if I wanted,  but 50yds is my preferred range.  A YHM suppressing it to the sound of a metal gate closing. My thermal is a ATN 100mm thor 640. I can count the jack rabbits at 800yds. It is a hog destroyer,  exsteamly accurate, and fun to shoot. 

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54 minutes ago, Hog Hunter said:

 My number one gun is a Stag arms Verminator chambered in 6.8 SPC.  Is talking about that round allowed on this site?

We don't care what the caliber is, here.  Read around - you'll see that quick.  :thumbup:

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