L. Cooper said,"I have read about shimming the action with pieces of plastic credit cards to get the barrel floated so you can run a test of what would happen when you actually do the free floating. You can also use the plastic to increase the fore end pressure by sliding a strip under that barrel as an experiment to see what pressure does in your rifle. If more pressure equals better accuracy, maybe free floating isn't a good idea."
I've used that credit card trick for years. It works just fine, and most of the time, credit card shims work just fine. Usually, I kind of glue them in place with some nail polish. If the free float works, with them in place, I just leave them there. If they don't work, the nail polish as glue will let you easily remove the shims.
There is a method to my madness on leaving the shims in place if it helps accuracy. Some companies. Sturm-Ruger especially, will not repair a rifle that has been altered in any way. A good example was the M77 I once had that I'd purchased second hand. The previous owner had free floated the stock, and while the gun was a good shooter, the claw extractor would not extract. I sent the gun back to them for repair and was informed that I would have to pay for a new stock. I let them know that the problem was the extractor, but unless I paid for a new stock, they would not fix the rifle. I told them to send it back, bought an extractor for a mauser and fixed the damn gun myself. Why? Because the replacement stock would have cost more than what I'd paid for the rifle.
usually, one thickness of an old credit card plced under the action at the rear of the recoil lug and another of the same thickness cut to fit under the tang at the rear of the action will suffice. This will still leave enough contact by the recoil lug to do it's job.
The real benefits of free floating and glass bedding, should you go that route is the rifle will be more consistant under all conditions. I have a Remington 700 BDL that is a consistant 1.5" gun with the load of choice hitting exactly three inches high at 100 yards. The rifle sits in an early H&S Precision stock made back in 1981 when their plant was still in Prescott Arizona. I sighted the rifle in three inches high with the 180 gr. Winchester silvertip ammo, and then worked up 180 gr. loads using the Sierra Pro-hunter and Nosler 180 gr. Partiton to hit at the same point of impact. All this was done in 1981. Just prior to hunting season, I take the rifle out and fire three rounds at 100 yards to check the sights. I can take that gun out tomorrow and it will hit right where it was sighted in way back then and probably ten years from now, if I'm still alive, I figure it will still hit three inches high with a 1.5" group. It is the most consistant rifle I own.
I used to own a neat mauser in 30-06 that would do .375" groups all the time. The problem was while it was consistantly a tight grouper, it never put the groups to the same place. I still have it, but now it's glass bedded into a McMillan Classic style stock. It's good for one inch now, most of the time,and shoots to the same place consistantly. I consider that more important that super tight groups all over the place.
Sorry if I got too long winded, but I hope it helps.
Paul B.