K2297

I'm going to be applying for a Masters Course at several universities (UK and the US) by the end of this year. I will be taking a recommendation letter from a professor at my current institute of study. The issue is that he would know me only for 4-6 months when he writes the letter for me. How is that looked upon by an admissions officer? Does that reduce the credibility of my LOR? I don't want my chances of getting admitted to become low because of this. Do you all know by personal experience or friends whether students have been admitted in top universities even though their letters of recommendation were written by professors who knew them for a really short period of time? Thank you.