[home made tracer slugs]

What is a foster slug?

[Got my M4 today. With some cool extras]

pIcked up today and stopped by Daves metal works. I got his 2 round extension, Oversize safety, Large bolt handle. Also installed the surefire fore end tri rail.

[My M4....Done! (Picture)]

Is that the Surefire rail? If so how was the fit?