Overindexed 305/ DA socom

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bcexmod

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Hi guys, the socom is over indexed, enough so that the sight is adjusted all the way to the right. I noticed that the gas piston housing is also not perpendicular with the rifle and seems off by the same margin as the sight is. The operating rod is not making perfect contact with the housing, ie it's a little off center.

Can the gas housing assembly(and someone please give the proper term for this) be readjusted? Ideally I'd like the barrel to sit perfectly aligned and for the headspace to be proper. What's the fix? Thanks.
 
Unscrew the barrel. Turn it back in to index. How much torque did it take? If the barrel is well torqued, that is it.
Remove the barrel. Upset the shoulder slightly with a rolling tool or light hammer (many light taps). Torque to index.
Remove the barrel. Machine the shoulder back. Fit a breeching ring, adjust so that the barrel pulls up and indexes.
Lots of folks have reset out of index barrels on these rifles.
 
Tiriaq has the correct answer.

But I would check your FH. I mailed one out today, that arrived with a 5 degrees over indexed barrel. Once I removed the FH and checked with a known perfect NM one I have, it was actually 2degrees under indexed!

I have seen Chinese FH as much as 11 degrees off centre. Most US made FH or Brakes are too close to measure, defiantly with-in 1.5 degrees of perfect.

John
 
What you guys are talking about is something I've never done. I'd love to try, but may need some of your wisdom. Tiriaq, you mention machine the shoulder. I have basic tools only. And the breeching ring? What is that?

And Medic, what is FH? Thanks, Dan.
 
bcexmod said:
What you guys are talking about is something I've never done. I'd love to try, but may need some of your wisdom. Tiriaq, you mention machine the shoulder. I have basic tools only. And the breeching ring? What is that?

And Medic, what is FH? Thanks, Dan.
Click to expand...

The shoulder is turned back using a lathe, and a thick washer machined to reset the barrel/receiver relationship.

FH = Flash Hider.
 
bcexmod said:
What you guys are talking about is something I've never done. I'd love to try, but may need some of your wisdom. Tiriaq, you mention machine the shoulder. I have basic tools only. And the breeching ring? What is that?

And Medic, what is FH? Thanks, Dan.
Click to expand...

What they are trying to explain is your barrel indexing could be perfectly fine as it can just have a badly machined flash hider ( machined improper out of alignment spline been cut thus give you a false idea thought your barrel is out of index ).

You should check the barrel index again with a known trued flash hider as John said before attempt to do anything.
 
Mine is a socom, with the reversible flash hider. Not sure if that relates to the badly machined flash hider. Is the gas assembly movable or is it permanently affixed to the barrel?
Spcamno said:
What they are trying to explain is your barrel indexing could be perfectly fine as it can just have a badly machined flash hider ( machined improper out of alignment spline been cut thus give you a false idea thought your barrel is out of index ).

You should check the barrel index again with a known trued flash hider as John said before attempt to do anything.
Click to expand...
 
bcexmod said:
Mine is a socom, with the reversible flash hider. Not sure if that relates to the badly machined flash hider. Is the gas assembly movable or is it permanently affixed to the barrel?
Click to expand...


You really need to take pictures and show us what problem(s) you have.

If your's a socom I would check the gas system / op rod alignment before come to a conclusion you have an over index barrel.

A picture is worth a thousand words (lol).
 
]Here in the pics I've drawn which way the sight is leaning. The gas system is offset by the same amount as the sight.

socom 2.jpgsocom.jpg
 

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Over indexed, cant tell for sure by how much..... but its more than 3*....

You will need a Barrel vise, a receiver wrench and a host of other tools to do the job properly. If you don't mid marring the finish, you can just torque the barrel in a good-sized bench vise and grab the receiver with a LARGE crescent wrench..... It makes fine tuning the indexing a bit sketchy but will break it free for ya.

I have $1000 into the barrel and receiver vise blocks, sight pocket and FSB blocks, angle finders and dial indicators. It's a reasonable expense for a guy doing 2-3 indexing jobs a week.

John
 
looks slightly over-indexed from the pictures, but I'm told you have to go by the gas port underneath.
 
It's tough to tell from the pictures.... but it does look slightly out.

But it could be an optical illusion as the rifle in the picture isn't square to the picture and the lighting isn't great..... it would help to see pictures that have lots of light, and shows both the rear sight and front sight with the receiver square to the picture.

Same advice above applies about checking with rods etc.

John
 
No, usually things are OK. But there are those that require tweaking, they're the ones you hear about.

As far as Nbhunt3r's rifle goes, it might be turned past index. Check the front sight base, make sure it isn't the problem, inspect the alignment of the gas system.
If it is slightly past index, I bet backing the barrel off, then bringing it to index would be all that might be required.
 
Nbhunt3r said:
What kind of impact would a slightly over index barrel have?
Click to expand...

Not much. The rifle would still function just fine. As long the over/under indexing is with-in +- 3* of TDC.

However, accuracy would not be as good as it could be. You would see wandering zeros, inconsistancy in group size, unexplained flyers etc.

Over/under index in the 3-5 degree range, would see all of the above and I estimate that the op-rod guide would have a bit of slop to start with. Over the course of 500-1000 rounds the roll pin would break (that holds the op-rod guide in place) and then your rifle would start to malfunction. Maybe one of those "my op-rod fell off, while firing" threads would then ensue!

Barrel indexing off by more than 5* is a pretty big deal IMHO. Rifle malfunctions and stoppages with-in 200-500 rounds. Continued use would eventually need a major overhaul.

John
 
I know that John probably has done more of these than all of us put together, but PLEASE don't clamp your barrel in a vice and pull on it with a crescent wrench. That is a horrible way to treat a good firearm. I see you are near Nelson. M14doc is up near 100 Mile House, I and probably numerous others have all the needed tools to do this job in the Greater Vancouver area. Someone may even be nearer to you if you create a new post titled "barrel tools needed near Nelson" and check for responses.
 
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