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Barrel Extension Source

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Replied by 13fcolt on topic Barrel Extension Source

What everyone else said.
Installing a barrel extension requires timing the threads and finish reaming the chamber so that head-space, index pin,and gas-port all line up as they should.

A mass production barrel gets it's gas port last, drilled in line wherever the index pin happens to be. A new barrel extension could fit, but the pin may not end where you need it. So it's not something that can just be switched out.
ArmaLite Super SASS for sale W/ extras. PM for details.
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10 years 10 months ago #25552

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Replied by faawrenchbndr on topic Barrel Extension Source

Thanks for the insight 'Colt

Did not know about the gas port being machined last, learn something new everyday!
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10 years 10 months ago #25557

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Replied by pookybear308 on topic Barrel Extension Source

13fcolt, I thank you as well...those are the details that have done the trick. I will start looking for something more complete.

That said, would it have helped at all if the seller of the barrel still had the original barrel extension? Just wondering for more complete future reference.
10 years 10 months ago #25578

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Replied by faawrenchbndr on topic Barrel Extension Source

Not to sound rude but I can not believe he sold you a barrel without an extension. I have never seen one 1st hand without an extension. I would suspect, shy of sending it to a shop like ADCO I'd say you are screwed on that barrel.
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10 years 10 months ago #25581

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Replied by Lizardette on topic Barrel Extension Source

No one has said anything that's wrong. Not at all.

Still, I'm a devil's advocate by nature, so here goes:

Checking headspace and if necessary finish chambering a .308 Win/7.62x51 barrel (or any other for that matter) is not that difficult if you have the right tools.

In fact, headspace gauges and finish reamers can be rented online with a minimum of hassle. I've used both 4-dproducts.com/ and www.reamerrentals.com/default.asp successfully.

Timing a barrel that doesn't line up right on its own can be more problematic, but isn't outside the realm of possibility if you have access to a lathe.

----

Should I continue with an explanation of what's involved?
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10 years 10 months ago #25586

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Replied by SOC on topic Barrel Extension Source

You can time an extension to a old barrel by taking a sanding disk and opening up the hole so the threaded portion of the barrel just fits through.

Thread on the extension tell you come against the disk then start turning the disk to remove material from the extension.

A washer between the disk and barrel will prevent you from sanding the barrel.

It can be very time consuming if the extension is not a close fit, but can be done.

I timed a FAL barrel to a new receiver this way but they were already a very close fit.

Go slow and don't overdo it.
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10 years 10 months ago #25590

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Replied by pookybear308 on topic Barrel Extension Source

OK folks...you win.
I will assume that I got hosed on this "bargain" barrel and move on to something more complete. The time, effort, and parts required to do this barrel right are beyond it's worth, I'm thinking. :(

In the meantime, however, I will ask the seller if he still has the original extension. By now it can do no harm and might be enlightening.
10 years 10 months ago #25607

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Replied by Lizardette on topic Barrel Extension Source

Pooky: incoming PM.
10 years 10 months ago #25608

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Replied by Lizardette on topic Barrel Extension Source

Talking with a friend who's much more an expert in the technical matters than I am:

It seems that the threads are different between the Armalite and DPMS extensions. The outside dimensions are apparently the same though. Word is that the bolts interchange as well. The carriers may have issues though, regarding the forward assist cuts.

Edit: Found conflicting information. Will update when I know more.
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Last edit: 10 years 10 months ago by Lizardette.
10 years 10 months ago #25609

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Replied by faawrenchbndr on topic Barrel Extension Source

I have heard the bolt carrier groups, AR10 vs 308 are interchangeable, but not recommended.
Have never seen a solid answer,......please post what you find.

Just for the record,....I can not/will not recommend anything DPMS!
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10 years 10 months ago #25618

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