Problems with ZM LR 300

[Aim4x]

Problems with ZM LR 300 top rail comes off after 15 to 20 rounds this is a Para USA. What fixes have worked?

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[Belevolk]

I always put locktite on my rails. Are you sure you have the right length screws?

 

[Aim4x]

I always put locktite on my rails. Are you sure you have the right length screws?

The top rail on mine is held by a spring loaded plunger in the gas block and rabbit and groove in the block on the chamber end are two pins. No screws are involved at all. I am not sure if this is unique to the Para USA ZM LR 300 or not.

 

[Sunky Heribeck]

Swap the plunger spring out for a stronger one.

 

[Aim4x]

Thanks, looks like I would need to remove the gas block to get to the spring and plunger then size the spring and try to find a replacement. I may have to do more research to see if factory spring is available. I am not sure if there is some sort of gasket between the block and barrel and whether a new one is needed once removed, like a crush washer?

 

[Sunky Heribeck]

There should be a roll pin retaining the plunger. No need to remove the gas block.

 

[Sunky Heribeck]

 

[Sunky Heribeck]

 

[Sunky Heribeck]

Drive the pin out, take the spring to Ace hardware and find one with the same diameter that has more resistance.

 

[Sunky Heribeck]

Upon further inspection of your photos, it appears your set up is different from the norm.

 

[Aim4x]

Thanks great video, just not my version. I guess I still need to find a schematic before I just start wrenching.

 

[Sunky Heribeck]

It appears roll pin 42 is what retains plunger 41 and spring 40.

 

[Sunky Heribeck]

ZM LR 300 Manual Download

 

[Aim4x]

Thank you Sunky. I see the roll pin just under the hand guard. I measured with my spring gauge it takes about 3 lbs to push the plunger in. I will still try to find a source for the factory one, but also remove what I have. There are limited stores here in Wickenburg to shop for springs, Ace Hardware and 3 gun stores. I just received my POF P415 Edge yesterday and dealing with the mess up of receiving a CA compliant rifle with that palm flag on the grip and a non collapsible stock. Not as advertised. Definitely have to have patience in this world.

 

[Sunky Heribeck]

I hope the spring fixes it. If not, the handguard top cover may be damaged. Does it fit tight or is there allot of play in it?

RE: the POF, At least both are easy to change out for freedom land parts.