Rooster Jacket substitute

Ken, What the 'Literature “is referring to is the effect of under and over lubrication. The two conditions are quite different in their effects on accuracy.

Over-Lubrication Over-lubrication is a term you may see used to describe the effects of using too much lubricant. This condition is well known to competitive shooters who use cast bullets. The most accurate condition is just enough lubricant so the barrel is left clean with minimal deposits. The presence of excessive lube in the barrel causes accuracy to decrease slightly. The important word here is slightly, this is quite different from the effect of under-lubrication Using a top quality lube where it is not required, or filling all the lube grooves with lubricant when only one groove filled is needed, gives a slight increase in group size. This can be demonstrated by using a machine rest with pistols, or careful bench rest shooting with rifles. The effect of over lubrication is small and is unimportant in most shooting.

Under-Lubrication The effects of under-lubrication are striking. Under lubrication leads to total loss of accuracy, and leading is often severe. Under-lubrication refers to both not enough lube and the use of a lube unsuited to the load.

My experience:

A carefully developed cast bullet load for a 308 Winchester rifle produced 1 ¼ groups at 100 yards with one lube groove on the bullet filled with lube. Filling all the grooves gives 1 ¾ inch groups. However, the load with one groove filled is suitable only for slow fire, with the barrel allowed to cool between shots. Attempts to use this superior accuracy load for rapid fire gave 4 inch “groups” after 10 fast shots. The second load, with the same lube and all grooves filled, is not affected by rapid shooting, and will shoot less than 2 inches all day long. The first load is temperature sensitive and will not group well on 100 F summer days, the second load is unaffected.

Target velocity 38 Specials lubricated in all grooves with a low effectiveness lube made with paraffin and Vaseline or commercial lubes made with only microcrystalline wax and shoot very well. In fact, switching to Alox 50/50 or other really “good” lube will actually enlarge groups slightly when tested in a machine rest. Alox lubricant in one groove or even part of one groove gave the best accuracy.

Attempts to use these same bullets with the low effectiveness paraffin and Vaseline lube in 357 magnum loads gave 6 inch 25 yard groups and heavy leading. Substituting Alox 50/50 in the magnum loads eliminated the leading and shrank the groups to under 2 inches.

Maximum accuracy is often found at the point where there is just enough lube. When the load is at the point of perfect lubrication it is also on the edge of under-lubrication. A change in conditions can easily push a load into under-lubrication with resultant loss of accuracy.

Most of my loads are over-lubricated, and for very good reason. I want them to perform in all conditions and in all guns. I do not want leading to appear suddenly because I plink a little to fast or it is a hot day. Hunting ammo has to perform under all temperatures. The slight “loss of accuracy” from over-lubrication is unnoticed in real world shooting. For general cast bullet loads, I use the best lube for the task at hand and I fill all the grooves covered by the case neck.

Steve Hurst

To be sure of hitting the target, shoot first, and call whatever you hit the target. - Ashleigh Brilliant