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i've seen where TAPCO is looking if there is an intrest. is there a difference between gas pistons? i know amd's and krinks are shorter.
 

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eldogg said:
i've seen where TAPCO is looking if there is an intrest. is there a difference between gas pistons? i know amd's and krinks are shorter.
I never gave that a thought. Maybe I thought they were the same as the 47, but if Tapco is looking at them perhaps they are different. This evening I'm going to have to check it out and make a comparison. Jack
 

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Happy Camper
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I just measured the OD of the pistons at the base where they attach to the carrier - about the same. In fact the '74 is just a little fatter, so '47 pistons will fit fine against the '74 carrier.

All the ones I measured have the same diameter piston, and so will seat properly within the gas blocks.

The dimensions are identical in every respect, except length. Length is different. Both of my Norinco AK-47s measure 5.8" long when mounted into the carrier. Actually 5.798" and 5.808".

I measured a plum '74 and black '74 kit piston, both were shorter - 5.645" long. I don't know how much this 0.1" matters?



What is the thread size of a '74 piston vs. '47 piston? Assuming they are the same...

... the question - I think - then becomes one of over/under pressure. If you use a longer '47 piston in an AK-74, the gas chamber will not fill with as much burnt gas during the time the bullet is in the barrel and therefore MAY - repeat, MAY cause an under-pressure situation which would ultimately result in less energy transferred to the action, therefore possible misfeeds. Also, this could result in less felt recoil.

Then again, the AK gas system is so over-powered that this is probably a moot issue - just as if you used both a ported gas block, and a ported gas tube.


So IMO, so long as the longer piston doesn't cause a safety concern, then the existing US pistons are "one piston for all".

Anyone care to comment on my thinking? Its not like a car where a smaller "expansion chamber" causes excessive buildup, it is building up pressure only while the bullet is in the barrel - correct?
 
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