I also posted on the triple-bar helmet thread. Nice to see a good, 100% original, untouched example of a "Dutch pot" here. I have one of these and it has the same crowned C mark on the peak tip as yours. I haven't managed to identify it yet beyond concluding that it's probably an arsenal mark rather than an armourer mark, as mine has what I'm fairly sure is an armourer mark elsewhere on the peak. I think the arsenal mark is probably continental, from the 30 Years War rather than for Charles 1, but with stuff this age it is very difficult to say.

Dutch pots have been faked within the past 10-15 years. The giveaways are the bigger carrying ring, skull made in two pieces and the bigger curve and flare to the tail.