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Discussion Starter #1
I've searched and found bits and pieces of infromation including Tony's videos but I thought I'd ask the Smiths and assemblers here for advice specific to my situation.

I have a new heavy barrel that isn't mounted. The accompanying oversized op rod guide has what I'd describe as a moderate press fit on the barrel shoulder. Tony's "pipe over barrel" method will almost certianly be needed. My questsions then are:

1. Is there a preference to install the guide before or after installing the barrel in the receiver?

2. If the answer is to install the guide before mounting the barrel, what is the best method to keep it aligned? Do you still just cross check it against the gas cylinder? I'm a little concerned that the fit will be tight enough that it might be challenging to rotate into alignment once fully seated.

3. I've seen reference to both epoxy and locking compound to keep the guide in place. Given the tight fit and one of those materials, I can't imagine that thing moving. Ever. But maybe I'm wrong. The heavy barrel isn't pre-machined for the roll pins. Are they (roll pins) even necessary?

4. Regarding the epoxy vs. locking compound. The thick epoxy makes sense to me where the fit was very loose and knurling was needed. In my case with a press fit between machined surfaces, the thinner liquid locking compound makes sense to me. Thoughts and advise?

Thanks in advance.
 

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Myself, I prefer to do the guide after the barrel is on.
Too much chance for one or the other out of alignment after the install.
How would you know where the correct position would be clock wise without a special fixture for the guide?
I do not use any (glue) to hold it in place, I straight knurl the journal on the back half only for a light press fit.
After positioning and setting in place,
I use a square face reamer to clean out any minor miss-alignment in the retaining pin hole,
or drill one if non existing..
I have never had one come loose in over 50 years and hundreds of installs.
 

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While you center the guide on the gas cylinder, you sort of need an oprod to do it. I would wait until the barrel is on the receiver.

As designed, the oprod guide will stay in place and the rifle will function, even without the cross pin. Original USGI stocks were inletted to hold the guide in place. There is very little stress on the guide, unless the oprod is damaged.

Of course, accuracy nuts will relieve the stock around the guide, so you need something to keep it from moving. It doesn't take much.
 

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Discussion Starter #6
Seems like agreement about installing after the barrel is on.

As far as locking in place, I think I'll go with loc-tite to start.

Thanks
 

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Seems like agreement about installing after the barrel is on.

As far as locking in place, I think I'll go with loc-tite to start.

Thanks
I don't know how much the barrel knurling tool cost, but that and some JB Weld would make it a very solid install.
 

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I like Allen Humphrey's question about OP rod guides!


I once had mine come off on my SM and re-glued it back on with green locktight... I cant remember the number but SAI uses it...
I was concerned on how to align the OP with the gas piston tail... I just did mine by feel and 'by guess and by golly'...


What is the correct and professional way to insure centered and correct contact?
 

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If you have a moderate press fit lock tite or epoxy should not be needed
For best accuracy center the op rod contact point on the gas piston tail as close as you can
If a slight rotational adjustment Is needed put a little heat to the guide before persuading , this is best accomplished before the guide is totally seated on the journal
 
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I like Allen Humphrey's question about OP rod guides!


I once had mine come off on my SM and re-glued it back on with green locktight... I cant remember the number but SAI uses it...
I was concerned on how to align the OP with the gas piston tail... I just did mine by feel and 'by guess and by golly'...


What is the correct and professional way to insure centered and correct contact?

Oprod guide goes on after the barrel is mounted.

Tony has a vid on this. Tony has a vid on everything for that matter.

You are aligning the oprod guide so the oprod is aligned with the piston.
So the piston is hitting in right the middle of the oprod. With an equal amount of oprod showing on all sides of the piston. I know I’m not communicating that well.
Think of a circle within a circle with all edges and spaced even.

I’ve never had my oprod guides come loose using JB Weld after watching what Tony used in his vid.
 
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