Over-indexed polytech M14: easy fix?

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My Polytech m14 is slightly over-indexed, and I'm a bit confused as to how easy it is to fix this issue.
- Is it as easy as unscrewing the barrel a few degrees after loosening the set screw?
- Or do I need to completely unscrew the barrel and get the shoulder rolled before screwing it back to the receiver?

The barrel is over indexed by maybe 3-4 degrees, enough to notice the front sight pointing left (I did change the chinese flash hider for a US one).
When I stick a small allen key in the gas port all the way inside the barrel , it sits at an angle.

I do understand that whatever the solution, I will have to re-check the headspace after the fix.

Thanks for your input!
 
If you have a barrel vice the fix is easy ( unscrew barrel a bit and check for alignment) and no need to worry about the shoulder , headspace or the set screw to do the fix either. These rifles are designed to have a generous headspace to begin with and moving the barrel out that amount would have a minimal effect on the headspacing anyhow. If the headspace is still a concern send some fired casings to Tacticalteacher and he will work his magic for you and let you know what it is. If you can't get it indexed locally and are stuck you can send it to me and I can fix it for free.
 
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That's a bummer! The problem is that you don't know how much barrel torque you have. If you only have a little, then unscrewing it means that your barrel could come loose. Headspace isn't much of an issue. Unscrewing your barrel 3˚ only extends headspace by 0.0008".

I personally would remove the barrel and see where it hand times. If it hand times anywhere more than 8˚, then I'd screw the barrel back on and get your indexing fixed. If it times 7˚ or less, I'd have the shoulder rolled or just replace the barrel since you'd already be going through the trouble of installing a barrel. Get a Criterion chrome lined barrel and call it good.

That's just what I'd do.

Tony.
 
Is the process easier if the barrel is under-indexed? I cant tell how many degrees because I don't know hoe to measure it, but the front sight is canted to the right when looking trough the rear sight. The front sight post seems to be machined slightly canted to the right also, so its even harder to tell for me how much under indexed it is. The oprod leans a little bit in that direction too.
 
If the barrel is over indexed you need to somehow add material between the front face of the action and the shoulder face of the barrel. That is not much of a trick if you give it a little thought.

You do need to remove the barrel to fix it. If you don't have the gear to do that, you'll need to find someone who does. You can send it to Vulcan Gun and he can fix you up. Just google it.

There are 2 methods that come to mind...

1) Remove the barrel and peen a series of small dents on the shoulder face of the barrel. That will raise the metal around the peens and push the barrel forward. It's not pretty but it will work.
2) Shim stock.... You would need to cut some steel shim stock to match the shoulder on the barrel, just like a thin washer. The tighten the barrel down with the shim between the action and the shoulder. If you get the shim right, your problem is solved. You may be able to find shims pre-cut for this purpose if you look. You aren't the first guy to have that problem. You could also contact a water jet cutting vendor to have them cut to your spec. Worst case scenario = scissors.
 
no shim stock LOL please don't try that

Tony Ben's answer is spot on pretty much.
and I'd just skip on by all the internet suggestions and take up chalkriver on his offer to fix it for ya LOL
 
I'm in the same boat mine is over indexed to (at least I think its over not under indexed). I've always wanted to get it fixed but I've got the gun set up so good right now I can't bring myself to take the scope mount off. :p
I'm hoping there will be a m14 clinic out here this summer.
 
Strip the rifle down to the barreled receiver (no gas system needed) as best as you can with the tools you have. Send it to me or Chalkriver. We will fix this for you.

Often (we did 6 of these at an EESA M14 Clinic) when people tell me that their barrel is out of proper index, we will knock off the flash suppressor since I don't trust them Kommunist made FS units to be square or straight (that sounded goofy.... ).

Then I slap on USGI (yes the real M14 flash suppressor) FS unit so that I can clamp on the parallels to determine if that barrel is out of index. 9 out of 10 times, we need to re-index. The rest of the suspect out-of-index jobs can be attributed to high school shop class quality flash suppressors. :)

If your barreled receiver is out of index as determined by my USGI flash suppressor, then I will fix your rifle! Easy peasy! :cool:

It will just cost you the return mailing. That's all! :wave:

Keep taking care of the noooobs out there! :p

Barney
 
Dake21 said:
Is the process easier if the barrel is under-indexed? I cant tell how many degrees because I don't know hoe to measure it, but the front sight is canted to the right when looking trough the rear sight. The front sight post seems to be machined slightly canted to the right also, so its even harder to tell for me how much under indexed it is. The oprod leans a little bit in that direction too.
Click to expand...

Sounds like under-indexed if front sight is leaning right on a square cut flash hider when viewed through the sights. You say the op rod appears this way too. I'm betting if your rear sight is centered at mechanical zero for windage, you rifle shoots to the left. My over tightened barrel with everything opposite to your description shot to the right at first.

Hungry's(Tactical Teacher) offer for proper indexing and flash hider QA'ing is the best deal you'll find on any M-14 car lot
 
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