Norc M305/M14/M1A significant vertical shift after first shot.

LUTNIT

LUTNIT

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I searched around for answers to this and couldn't find this specific problem being discussed except as a comment in passing that wasn't really addressed on a different forum. I found many people saying it was a problem with the shooter but this is the only rifle that does it and it does it with my 4 friends exactly the same way as well.

At 50 yards the cold shot from my Norc M305 hits PoA. Any follow up shots group together 2-3" below the cold shot. If I wait a few minutes before firing again it groups with the first shot. It happens with any factory ammo I try and I tested 3 different handloads the other day and all had exactly the same results; first shot hit PoA and the next 4 where all touching but 2-3" below the first (factory ammo is a 1" or so group below the first).

Since the shots do all hit the same PoA if I wait a few minutes between shots I thought maybe it has something to do with the heat up of components?

I have a no-name steel scope mount and a Gold Crown scope made by Nikko Sterling that shot fine when it was on a couple other rifles. The rifle is unmodified as it came from the factory and doesn't appear to have headspace issues. All loads are full length sized. Powders where H4895 and IMR4895 and the bullets where Hornady .308 150gr FMJ/BT. Brass is "Winchester" headstamp and primers are CCI #200's.

Has anyone seen this before? Is it possibly something that unitizing the gas block could fix? One guy at the range told me to buy a new op rod spring, another guy said I need a complete USGI bolt, and another guy said I need to get a USGI fibreglass stock.
 
Are you lubing the front band and stock ferrule interface? If so, maybe you can try shaving back the stock with the ferrule removed leaving a millimeter of space/just enough for light to pass through. That way the barrel should come back to the same position after each firing instead of being caught up by friction.

Another possibility is the rear of the top hand guard, if it is touching to much on the receiver, accuracy can be affected. You can trim off a bit off the rear to give some clearance. Also lube the top handguard clip and the clip grooves in the barrel.

I'm not sure, but it seems like a consistency issue with the way the barrel resets in the stock after firing and maybe even the way the barrel heats/cools affecting its position in the stock.

Be interested to see what the group would look like if you waited 5 minutes in between each shot.
 
One thing you could try is take off your optics and shoot with your iron sights for groups. It has been proven time and time again, if your not paying for top of the line mounts for optics on an m14, you will have a wondering point of aim.
 
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