M305 piston

[Denka]

I got piston(from M305) for DA Socom and tried to replace with existing one(has to much wear), however, piston does not go all the way in as original one. Is it common that parts might vary in size?

 

[Pr589]

Denka - I am going to ask a dumb question but I'm not trying to be insulting. Have you checked to ensure that the lower part of the piston that is "D" shaped is seating into the gas cylinder correctly.

If you have done so, use some calipers to check the piston diameter against your old one. I have swapped pistons and have had no difficulties.

 

[Denka]

Denka - I am going to ask a dumb question but I'm not trying to be insulting. Have you checked to ensure that the lower part of the piston that is "D" shaped is seating into the gas cylinder correctly.

If you have done so, use some calipers to check the piston diameter against your old one. I have swapped pistons and have had no difficulties.

I know about D shape. Asked question if this is a common thing.

 

[estampidate]

By the way, I tried to extract my M305 gas piston but it was impossible without remove bayonet support (no enough clearance to extracted from the tube)

Any hints to do it?

 

[cheeseburgereatin]

with the piston still pushed all the way in you must rotate the outer 8 shaped ring counterclockwise to loosen it a quarter turn then the piston will have enough clearance to come out.

 

[Pop]

OP I'm just curious, but what sort of wear are you seeing on your old piston and what's the approximate round count on the rifle? Are you starting to experience failures to cycle? If you had any pictures you could post of the piston wear that would be greatly appreciated.

 

[jt_trouble]

Could i replace a worn norinco piston with say a SEI piston and have it fit properly?

 

[goldenbb]

Could i replace a worn norinco piston with say a SEI piston and have it fit properly?

You could insert it in the cylinder but it will rattle around in there. Function and accuracy will degrade. The tolerance is supposed to be very tight. The Norc pistons and gas cylinders are larger. See post #7.

http://www.canadiangunnutz.com/foru...I-parts-compatibility?highlight=Compatibility

 

[yomomma]

No Norinco piston is bigger by a few thousands of an inch. When I replaced my cylinder I put my piston on my lathe and took about 2 thou off the diameter

 

[jt_trouble]

No. See post #7.

http://www.canadiangunnutz.com/foru...I-parts-compatibility?highlight=Compatibility

thanks!