I have a Rock River Arms NM Rifle with the 20" heavy barrel. It has the fixed Buttstock. I purchased a Magpul UBR Buttstock today and was reading the install instructions. Step 2 there is a note that says "if you have an A1/A2 fixed stock using a rifle length receiver extension, the buffer and spring must also be replaced". Do I need a new buffer and spring?

IIRC, Needs a carbine buffer and spring.

Thank you for your reply.....That's all I need? A carbine buffer and spring? Anything specific..length, commercial, mil-spec?

The UBR uses a proprietary receiver extension tube. All you need is a carbine length buffer, and a carbine action (buffer) spring. As for buffer weight, being a 20" barrel I would look into a H6 buffer. Use coupon code SUMMER30 to get an additional 30% off the H6 buffer.

Thank you for your help. I am pretty knowledgeable about this AR. I never had to deal with buffers and springs. The only reason I'm switching the A2 stock out is so my wife can shoot the AR. The stock was uncomfortable for her. After my initial post last night, I did some google searches on buffer springs and buffers. I went to the local gun shop this morning and picked up a RRA spring kit for a carbine. I picked up an H2 buffer as well. I will try the H2 first and if need be, I'll try the H6. Thanks again!