That is so cool- I've done some designs of roller guns in my computer, but haven't taken the plunge and tried to make it work yet. I was going to have two sets of rollers so the loading force wouldn't be so dramatic- but it makes the layout more complicated because I was going to have offset axles.

I'll send you the sketch if you want Charile.

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"America will never be destroyed from the outside. If we falter, and lose our freedoms, it will be because we destroyed ourselves." A. Lincoln