Ideas about getting a loan against a 401k

[Cody Stone]

I have recently thought about getting a loan from my 401k to buy an investment property. What I learned is I can pay a $50 fee and have 4% interest rate. The interest I pay goes directly back in to the 401k. In essence I pay myself the interest. Pretty cool, but what I also learned was the monthly payments I make on the loan is with after tax dollars. So I'm paying taxes on the money twice, pay back on the loan and again during retirement. 

Does anyone have experience with doing this? Any thoughts on if it's a good idea? Pros and cons of loans against a 401k?

Thanks in advance