Armstrong Heraldry

Arms are granted to an individual and are inherited through the direct male line. They are not granted to families nor simply to people with the same name. Many people with the same surname will have different coats of arms. Most won’t be entitled to any at all. 

If you believe you have an ancestor who had a genuine coat of arms and you can prove your pedigree in the male line you can apply to the College of Arms. (I believe there will be a fee).

Arms usually vary over time according to changes in a person’s circumstances. For example, a marriage may lead to them being modified to include symbols for the new family.

See:   http://www.college-of-arms.gov.uk/Faq.htm

You could submit your arms to the College and see what they can tell you about them.