OP rod and OP spring guide lining up issue on m305

Arcteryx

Arcteryx

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I recently had my new M305 out and noticed my OP rod guide had moved a tiny bit to one side. I had mentioned it in a previous post. Not that big of deal I will fix that. But I think I found the cause of whats forcing it off centre.

Now the OP rod is just off centre a few degrees and doesn't quite line up with gas system maybe only a heavy 1\8th of an inch. But now it cycles better you can feel it when you dry cycle it. If I line up on the OP rod guide to the gas system it tightens back up and the OP rod lines up nicely. But it feels ####ty to cycle, you can feel it grinding like it has pressure on the OP spring guide making it bind a bit. The issue I am noticing is that when I tighten up the OP rod guide I can see it flex my OP spring guide where the guide is flat and fits into the slot. I feel like the slot in the receiver that holds my OP spring guide is angled that tiny bit off true and is forcing my OP rod guide to push off centre. The OP rod itself is still straight. I recently purchased a new OP spring guide from m14.ca and I tried my old one. They both act the same way. Since the slot seems to be off a tiny bit what is the best way to fix this. File the slot (which is very tight atm) to relieve the tension on the OP spring guide. I am assuming this isn't the best option to have sloppy a fit? Or bend the flat part of the OP spring guide that tiny bit so everything lines up, which is probably easier said than done if its hardened it could just snap on me. Any input or suggestions would be much appreciated.

Thanks.
Arc
 
1-trident-1 said:
measure the width of the slot and post.
Click to expand...

The slot is the exact same width as my m14.ca OP spring guide. Its a heavy 1/8th where the factory one is a small 1/8th. I usually need a screw driver to get enough pressure to slide out the m14.ca spring guide. Its a very tight fit. I even need to give it a gentle tap with the handle of the screw driver to push it back into place. I am now thinking that maybe running my file in there just to give it that bit of play isn't a bad thing. If I file it at the right angle might give it enough relief to take the pressure off the OP rod guide.
 
do not file anything !

is it dry or Greased?

does it pass the tilt test with trigger group?

does it pass the tilt test with trigger group removed ?
 
How are you tightening your op rod guild? The proper way of doing it is to get that part of the barrel peened or knurled and then reinstall the guide. Alternatively, if it was a Garand or M14 build it could also be silver soldered. I believe that most of the m305 op rods are just slightly off rather than the op rod spring guild or the op rod guild itself. The rifle will still function and cycle as it should but if you want a perfectly positioned op rod, I am afraid that you might have to buy a new/used USGI op rod or an m305 one that is in spec, have it aligned before securing you op rod guild. Several m305s have come across my work bench with the same problem as yours and it was the op rod that was out of spec. I have never tried bending or reshaping the op rod because when I was working on m305s, I just bought a bunch of op rods knowing that this was a common problem. If you want to try the op rod route an m305 one range from $50 to $100 and a USGI one would be 3Xs that.
 
just having some fun said:
do not file anything !

is it dry or Greased?

does it pass the tilt test with trigger group?

does it pass the tilt test with trigger group removed ?
Click to expand...

yes its greased

I will do a tilt test with the trigger in a few. It passes tilt test on its own without trigger no problem. Where it fails tilt test if I take the spring out and leave the round OP spring guide in place it gets 85% of the way down before rubbing down the side of the OP spring guide. Which is why the flat factory one worked ok, I had maybe 40 rounds through it like that with no issues. Now that I have the round one there is no way it will function properly if I fix the loose OP rod guide. I will take a picture to show how off it is this evening and to double check my OP rod isn't bent in any way that would make it do that. I will also check to make sure the spring guide is in line. Has anyone ever had an out of spec OP rod from a new norinco?
 
Garaldtao said:
How are you tightening your op rod guild? The proper way of doing it is to get that part of the barrel peened or knurled and then reinstall the guide. Alternatively, if it was a Garand or M14 build it could also be silver soldered. I believe that most of the m305 op rods are just slightly off rather than the op rod spring guild or the op rod guild itself. The rifle will still function and cycle as it should but if you want a perfectly positioned op rod, I am afraid that you might have to buy a new/used USGI op rod or an m305 one that is in spec, have it aligned before securing you op rod guild. Several m305s have come across my work bench with the same problem as yours and it was the op rod that was out of spec. I have never tried bending or reshaping the op rod because when I was working on m305s, I just bought a bunch of op rods knowing that this was a common problem. If you want to try the op rod route an m305 one range from $50 to $100 and a USGI one would be 3Xs that.
Click to expand...

I haven't tightened it up yet since I noticed it was loose. I am going to knurl it and new pin. I agree, I didn't want to line it up with an out of spec OP rod and waste the time if this one was really bad. Maybe I should try replace it and see how it lines up. If I leave it off centre it cycles ok. I did figure I would have some parts to replace when I purchased a new rifle.

That is good to know that its something people have seen. Its not unusual to see out spec OP rods. I will go play with it some more this evening and order up a new op rod and spring tomorrow.
 
This could be a few things.

Barrel timing is one, a bent or out of alignment op-rod or just maybe that slot. The slot is my last suspect though.
 
I think you have one of the recent imports

Last 15 years or so more tweaking has be done on these new rifles than all the tweaking done before that time

I think Barrel is out of time..
you can not even tell on some of them because front sight is sometimes machined wrong too

unless your oprod is bent

Did you shoot it with and 180g or any superformance rounds

it could also be another problem hard to tell with out having in front of you and checking it
 
just having some fun said:
I think you have one of the recent imports

Last 15 years or so more tweaking has be done on these new rifles than all the tweaking done before that time

I think Barrel is out of time..
you can not even tell on some of them because front sight is sometimes machined wrong too

unless your oprod is bent

Did you shoot it with and 180g or any superformance rounds

it could also be another problem hard to tell with out having in front of you and checking it
Click to expand...

It is a 2014 import and a fresh rifle. I expected it to need some love.
One of the first things I read about with these was to stay away from the heavy rounds and hot loads. The only rounds ive had through it are federal gold medal sierra matchkings at 168 grain, 2650 fps. Only rounds I could find that were not 2800+
A friend I shoot with at the range occasionally has one of these and he warned me right away about the 180grain rounds. He told me his first trip out with his new m305 he blew the OP rod right out of his gun.
As far as barrel alignment and timing goes, I will have to look into that further. The front sight is sitting straight and not over rotated but I could see that as not definitive proof. Im assuming the barrel could be over torqued and still have a straight front sight since the seem to tack them in place? I still want to get the headspace measured too.
 
The timing can certainly “look” correct.
The issue with these is sometimes the flash hiders have canted sight bases. This can give the illusion everything is straight when really the barrel is over or under timed.

One way to see if the hider is one of the crummier ones is check to see if the set screw hole is lined up with the top flash hider spline.
 
Some of the flash hiders are so far off you can not use them as a guide
I have a bunch of junk flash hiders .. One the set screw is 1/8 inch off center
usually the splines inside are off
i have one where the cuts at the end are off center

to do it correctly you have to use a US Made or USGI flash hider


jonh172 said:
The timing can certainly “look” correct.
The issue with these is sometimes the flash hiders have canted sight bases. This can give the illusion everything is straight when really the barrel is over or under timed.

One way to see if the hider is one of the crummier ones is check to see if the set screw hole is lined up with the top flash hider spline.
Click to expand...
 
just having some fun said:
Some of the flash hiders are so far off you can not use them as a guide
I have a bunch of junk flash hiders .. One the set screw is 1/8 inch off center
usually the splines inside are off
i have one where the cuts at the end are off center

to do it correctly you have to use a US Made or USGI flash hider
Click to expand...


Correct, you never use a canted Chinese flash hider as a guide, usgi or US made ones only.
 
Id look at the barrel timing as mentioned above. You get the guide to line up with the gas system, they are relative to eachother but if the barrel is off by a couple degrees it will all be slightly twisted relative to the reciever. Oprod could be bent but its less likely on a new rifle. Its possible though and if so norinco and USGI parts are usually available on the EE ans not too expensive even for a GI one although it may need a little fitting.
 
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