Well it's a good question that I cannot answer just from memory, and I don't have access to an MC21 barrel to check, so someone else will have to chime in.

I suspect you're probably making a bit more out of it than necessary though, but if you are indeed feeling up into the barrel in the correct area (which is actually pretty difficult to judge), then no, I wouldn't expect it to be 5mm!

I've just had a look at an HRC MC16 barrel here, but the port's too small to get my fat sausage finger up, so hopefully someone with an MC21/28 barrel can have a look.

As a side note, are you sure you're not confusing the back of the RC Valve (the part closest to the expansion chamber) that can often protrude into the exhaust port...


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Andy.
NSR-WORLD.COM

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