20"modification

[PJW]

Hello, I owns a DPMS .308 and have switched to an anderson 20' barrel. The rifl shoots and cycles well, however wont lock open on the last shot. has anone ever had this issue?

[shepp]

Welcome to the forum feel free to tell us about yourself in the intro section

 

lots of people lol

 

what kinda mags you running? Have you tried more than one kind? Factory lower or you built it? If so what kinda bolt catch? Will it lock back manually using the charging handle?

[PJW]

It does lock back manually. I have tried the Mil Spec and Mag Pull Mags. Its a factory lower with a stock bolt catch from the orignal. I bought a rifle length gas tube & used the same gas block.

[survivalshop]

  Gas Block may be not aligned with the Barrels Gas Port correctly . 

  Barrels Chamber may be rough & need polishing ( slows extraction & lowers recoil needed to fully reciprocate BCG past Bolt Catch.

  Could also be Port size in Barrel , too small ( we are seeing a lot of it lately )

  Head space checked ?

Edited August 16, 2017 by survivalshop

[PJW]

The head space has not been checked. How do I make sure that the gas block is properly aligned. All I did was eyeball it. What is the proper barrel port size? What should I use to polish the chamber?

Thanks.

[survivalshop]

7 hours ago, PJW said:

The head space has not been checked. How do I make sure that the gas block is properly aligned. All I did was eyeball it. What is the proper barrel port size? What should I use to polish the chamber?

Thanks.

  Fist thing would be to check Head Space , its never a good practice to swap a Bolt from one Barrel to another . If the Bolt was only used for a few rounds before switching & has no time to seat . You should check Head Space to make sure its not an issue.

  As far as the Barrels Chamber , it should be inspected to see if there is an issue with Burr's , scratches , or imperfections before any work is done to it . Flitz metal polish & a Bore mop & battery operated drill to polish it , but only if it looks rough . Imperfections in the Chamber will more then likely no be buffed or polished out.

 You can use a Drill index of different size Drill bits & use the Shank of the Bit to come as close as you can to a close size .

 

[PJW]

Thanks Much Survivalshop.

PJW

[survivalshop]

9 minutes ago, PJW said:

Thanks Much Survivalshop.

PJW

 I assumed it was working before the Barrel change out ?

[98Z5V]

On 8/16/2017 at 5:20 AM, PJW said:

Hello, I owns a DPMS .308 and have switched to an anderson 20' barrel.

 

6 hours ago, survivalshop said:

 I assumed it was working before the Barrel change out ?

That was going to be my question in this...

It ran fine and locked back on the last round with the original barrel?...

If it did, with whatever the original barrel was, then start drilling your Anderson 20" barrel's gas port UP in size.