pacomb,
Good for you, keep doing whatever works for you, even if it differs from something any of us advise. You might ask your "construction" friends about hardened cut nails (used to fasten wood to concrete), they are also tapered similar to horseshoe nails, but a more even taper. We called them "case hardened", but I think they were " through hardened"; that is not important for your use, what is important is that they are cut, flat, and tapered. Cut nails for hardwood floors may also be helpful to you.
Mike
Mike, do you have a photo I can have as an example??
