Barrel extension

[Nyx]

Are there any differences between AR-10 and DPMS barrel extensions.  I know that the barrel nuts are different but can not find out if the extensions are different.

 

The reason is I am having a barrel made and want to supply the gunsmith with barrel, barrel extension and bolt for chambering and head space.

 

Thanks in advance,

Nyx

[survivalshop]

  Is there something special about your Barrel that you want to supply a Barrel Extension separate from the Barrel ?

     Most just purchase the Barrel with an Extension on it already by the Barrel Manufacturer. Like 99.9% do . I have not had an issue with Head Spacing any Bolt from a complete Barrel assembly , some may be tight when using a NIB coated Bolt until a period of break in , but I've never had an issue with a Barrel with the Extension applied & HS checked by a reputable Barrel Manufacturer .

   I would say there is a difference , its why just about everyone uses a matching Bolt to one or the others Barrel Extension . Its pretty common practice to use a DPMS 308 Bolt with a DPMS Barrel & a Armalite AR 10 Bolt with a AR 10 Barrel assemblies . I would be concerned with tolerance stacking with Bolt fitment & its an easy thing to just use the matching manufacturers components .

[Nyx]

The barrel supplier that I prefer only offers drop-in items that have threaded muzzles.  I was thinking of having them making a barrel without a threaded muzzle.  If I have them make a barrel that I want it will have to go to a gunsmuth to be threaded for the barrel extension and chambered since the they won't preform that task for a custom barrel. 

Before I finally decide I would want to know that I have all my ducks lined up.  Is there dimensional differences between DPMS and Armalite barrel extensions?

 

Thanks in advance.

[MikedaddyH]

The reason the barrel maker requests a bolt is to headspace your barrel combnation. The process starts by profiling the barrel in a lathe then the threads are cut into the barrel. Next the barrel extension is test fitted and material is removed from the back of the barrel until the spacing is correct. The next step chambering is done , then the barrel extension is installed and placed in a upper receiver and headspace is checked. If it is not within limits barrel comes out of upper barrel extension comes off and material is removed from the back of the barrel to bring it into specs ,then reassembled and headspace again. This time its in specs and done unless you want a threaded barrel which is the next step followed by working on the crown and timing a muzzel device.

 

[MikedaddyH]

4 minutes ago, Nyx said:

 Is there dimensional differences between DPMS and Armalite barrel extensions?

 

Thanks in advance.

NO !

It is not like that special set of matched tires. Lol !

[Nyx]

MikedaddyH,

Thanks for the reply.  Yes, that is why one needs to supply a bolt when chambering.  I would be majorly disappointed if my new build suffered a case eruption and sent uncontained pressure and case shrapnel back through the upper, lower, bolt, magazine and/or me. 

I am building a Rhino Arms upper/lower set and have not decided on caliber choice 260 Rem / 308 win.   I already have a Armalite AR-10T that is advertised as a 1 minute gun and it is about one minute with decent ammo.  Hopefully the Rhino will be about 1/2 minute when done.

 

Regards, 

Nyx

[MikedaddyH]

That is an easy choice. If you don't have a 308 get that build done first then do the .260Rem second .

[survivalshop]

  I would still use corresponding components , I have read quite a bit that there are differences in the two bolts ( AR10/DPMS ) dimensionally ,the AR10 being beefed in the lug area , but as MikedaddyH posted , if your starting from scratch , a good Smith should be able to head space both of them . 

 The last process is aligning the gas Port on the Barrel with the Barrel's extension Pin, this alignment is crucial . 

[Nyx]

48 minutes ago, survivalshop said:

 

 The last process is aligning the gas Port on the Barrel with the Barrel's extension Pin, this alignment is crucial . 

Yes, I will check with the barrel maker to make sure the gunsmith will drill the gas port.  Also thanks for the heads up on that tip.

 

Regards,

Nyx.       ( It took awhile to figure out how to do a partial quote and then add my text out side of the quote)

[MikedaddyH]

Drilling the gas port is done last after the barrel his in the upper receiver and the appropriate size is important . 

[Nyx]

Yes, I can see how the size us important.

After the barrel extension has been added and pined it would seem that it would be a good time to drill the gas port.  I was planning on using an adjustable gas block to tune it.  Also relying on the gunsmiths input on the subject.

Thanks,

 

Nyx

[survivalshop]

  Yes , size does matter ! 

[Nyx]

Hey, you didn't have to laugh at me.

What were we talking about...