They are late HRC "D" SP barrels. Only very slight differences, mostly in exhaust and RC Valve areas, but still need working to get optimal performance.
Only for those with very deep pockets. Hard to justify, in my opinion, unless you really need HRC barrels for some reason!
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Andy.
NSR-WORLD.COM
Please keep all responses to Forum posts on the Forum so that others may benefit.
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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