Best you (a) measure that barrel, and (b) pull the other one off to check that too!
If those pistons are indeed RM items, you run the risk of massive detonation if you replace them with NSR pistons and the barrels have already been machined to compensate for the single ring items.
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Andy.
NSR-WORLD.COM
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Please DO NOT PM me for technical advice. My time is precious, and you will probably receive a faster response on the Forum anyway.
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