Did you mean model railroad spikes to act as 5th stting capos. I put one on my 1967 Vega the week I purchased it and it's functioned perfectly.
Capo on the fifth fret in G tuning. Slip the fifth string under the spike. Voila, open C tuning. I like it a lot better than the traditional C-tuning.
The trick is to drive it into the neck close enough to the fret so the bend in the string kills any vibration, but not too close of you'll have trouble gettting the string under. Figure an eight of an inch.