Wanting to test the theory of shooting off a "Sheath" protected bore for the first shot off a clean barrel, I went out 10-26-06 and did a lot of cleaning and not much shooting.
Swiss 3f is usually a great shooting powder for me. Today for some reason it was giving me fits. I applied the Sheath. I waited and then ran a dry patch down the barrel and fired one RWS cap. Pulled the dry patch and loaded 70 grains of Swiss 3f and a BullShop 500 gr NEI conical.
The first hit on the clean barrel was a little low, but I actually think it was my fault. I say this because as I was concentrating on the shot, the gun fired. I can not say for certain my scope placement was perfect nor my breath as it should have been. It hit 1" low. I was shooting at a 2" circle in the center bull. And it hit just under the bull. The next shot took most of that taped on bull off. And the next ones kind of finished off my fancy tape on bulls eyes. I then got some transparent tape and made sure the little bulls were stuck on better.
I had an audience today. This old man, my neighbor stopped over and was fascinated with my White rifle. He did not want to shoot it, but was more then interested in the fact he saw the Triple Se7en group being shot.
I then pulled the White apart and cleaned the barrel with Rusty Duck Black Off solvent and dry patched it. After that I put it all back together and ran a patch with Sheath down it. Then a dry one, popped a cap and got ready to load Triple Se7en 3f. The Triple Se7en with the Sheath coated bore shot perfect. That is a four shot group.
I then cleaned that White Rifle AGAIN! Sheath in the bore. Popped a cap. And loaded with Goex 3f. The one shot it pulled (#3 of four) with the Goex was my fault. (lower right bull)
I then cleaned the rifle again. Did the same routine with the Sheath and tried American Pioneer 3f. Whether the Sheath made a difference I could not say. I just can not get that powder to group a conical.
Since my cheering section was getting bored, I set up some pop cans. Using the Triple Se7en powder, we knocked them over then tore them apart in the steel bullet trap. Until I ran out of another box of the Bull Shop conicals.
So did the Sheath make a difference. I personally think it did. This rifle always threw them 2" on a clean barrel. I think this Sheath might be my ticket to hunting on a clean rifle. Thanks for the idea guys. I still want to test it again, so maybe tomorrow we will go shoot... 
One concern was raised over this testing. When I swabbed out the Swiss, it was a very black, thick, almost wet looking fowling. Whether this was caused by the Sheath I can not say. All I will say is with the 777 it did well. Also when I used Sheath in the barrel for the Goex test, it was the same Sheath patch I used when swabbing out for the 777 test, with no additional Sheath added. So, did it coat the barrel lighter, who knows. Looks like I have more testing to do. Better get at it too... the range is calling.