Gun rest?? Hamburger arm

[judgemint]

We went out today to double check the iron sites on the 30 06 . I am new at shooting high powered rifles.(or any other firearm) I shot a box of 20 a couple weeks ago from a stand up position, a piece of cake my arm didn't bother me a bit. went out with a good ol boy today to make sure everything was set right. we set up with sandbags and sat on a bench at a range. I don't know if it was the angle of the rear bag or what but my shoulder felt like a stick of butter from the first shot, and a couple of times it was all I could do to shoot. maybe I held it wrong or something? My arm feels like raw hamburger tonight. I shot a few times in the stand up pos and it didn't wipe me out like sitting down at the bench. I'm 6' 1" 225lbs and I felt like a 12 year old girl on the bench. I was wondering if anyone uses those shooting rests? are they worth a damn? Do they help reduce recoil??