I've shot NRA and ISU Small Bore with a H&R 5200 (Clone of the Model 52 Winchester) its heavy but with a proper position, you wont notice.
Same thing with my Model 70 300 Winchester 1000 yard bolt gun. It's heavier then my 5200. (29 inch Heavy Barrel, sligjt taper from 1.125 at the action to .96 at the Muzzle). Again with a proper position it can be confortable in the prone.
What you need is a good coach to get you in that postion. Best place to find that coaching in the Civilian Marksmanship GSM Clinics. There is lots of GSM Matches in Mich. The clubs that put on the matches also put on the clinics. They can be found on the CMP Website.
Basicly there are two types of prone positions. One is the straight leg position with all your weight on your stomach and chest. (Referred to as the Little Green Army Man position, like the little soldiers we played with as a kid.). This is common when shooting off a bipod or sandbags.
For a position used in competition like small bore or high power there is the cocked leg position. This is the most stable, and with a heavy rifle, the most comfortable. You cock the leg on your shooting side (right leg for right handed shooters). This brings you knee up, turning you a bit on your left side (Right handed shooter). It puts you on your side, taking the weight off your diaphram allowing easier breathing. The left, supporting elbow is almost directly under the rifle. Head is as straight as possible allowing you to get the good "Chipmunk" spot weld, where almost 100% of the weight of the head is on the stock of the rifle.
Here is a perfect example of that position:
It's hard to explain the position to someone you can't see, I don't know your body make up, but I do know there IS NO ONE WHO CANNOT BE GOTTEN INTO A GOOD PRONE (or any other positions) if they have a good coach.
One of the responses to this post some one mentioned they can't shoot prone because of the stomach or what ever. It's not that they can't shoot prone, its that they have been shown how to shoot prone.
I don't shoot as well as I use to, I don't take it near as serious as I did before I retired and stop coaching and shooting for the NG, but I still coach, I am a CMP GSM Master Instructor, I've been coaching for about 30 plus years sense I attended the NG MTU Coaching Clinic. I have never found anyone I couldn't get into a prone (or any other position). If you were closer I'd fix you up.
Baring that, the Civilian Marksmanship Program has several training books on shooting, below is two that I think will help you the most. Only $6.95 Each.
https://estore.odcmp.com/store/catal...4=¬e5=&max=
https://estore.odcmp.com/store/catal...4=¬e5=&max=