In worn barrels I get the best accuracy with flat base bullets and during WWII the U.S. loaded the double base BLC2 powder for .303 ammunition for the British.
rhino519, your asking about loads "BUT" again you may have a rifle that has not been touched by an armourer in over 40-50 years. Your fore stock may have wood scrinkage, the forward trigger guard screw collar/bushing may be too long. Meaning your bedding should be tightened up per your Canadian No.4 manual and then work up some loads. When the bedding is correct and your shooting circular groups then you "tune" the rifle by adjusting the powder charge to make the groups smaller.
There are two basic ways to "tune" a rifle, adjust the bedding to control barrel vibrations and accuracy. Or adjust the powder charge to control the barrel vibrations, and on the Enfield rifle you need to do both. If you want your Enfield rifle to shoot well you need to understand your fore stock, and how the bedding effects barrel vibrations.
You also have another very good Canadian manual on bedding the No.4 "The Canadian Marksman" which shows the combined effects of center bedding and also up pressure at the fore end tip.
One of the first things I did with a new Enfield rifle was remove the fore stock and let it soak in a 50/50 mix of "raw" linseed oil and turpentine for a day or more. This would cause the dry wood to swell and in many cases fix any wood shrinkage and loose bedding problems you have. But you may still need to shim the stock as the armourers did to adjust the bedding forces.
The Canadian Marksman (Bedding the 7.62mm No.4 Rifle) - 1965
http://www.milsurps.com/content.php?r=305-The-Canadian-Marksman-%28Bedding-the-7.62mm-No.4-Rifle%29-1965
1991 No.4 (All Marks) .303 Rifle Manuals (Complete Set)
http://www.milsurps.com/content.php?r=335-1991-No.4-%28All-Marks%29-.303-Rifle-Manuals-%28Complete-Set%29
Know thy rifle..........All the information in the world is written in books and all you have to do is read.