Homemade lube test.....

[Harry O]

I have read here the three ways that lube gets from the lube groove to the barrel. It seemed to me that the major factor was the acceleration of the bullet and the viscosity (hardness) of the lube. When the bullet is fired, the lube (due to inertia) moves back and when it hits the back of the lube groove it has no way to go but outward into the barrel. The higher the acceleration, the harder (more viscous) the lube must be. The lower the acceleration, the lube can be less hard.

I use SPG lube for my black powder guns and low-speed smokeless-powder guns (like CAS loads). It has low viscosity and works well. I use NRA 50/50 lube on my higher-velocity pistol and lower-velocity rifle bullets. It works well with .357 Magnum, .30 Carbine, 30-40 Krag and the like. I have never been totally happy with it when it came to medium velocity loads, like the .38 Special, 45LC, 38-40 and the like. So I finally decided to try something. BTW, I have NEVER been happy with the hard "crayon" lube that comes on some of the bullets I have bought.

I took some old, some partial sticks, and already melted pan-lube 50/50 lube, melted it together and added a little mineral oil to reduce the viscosity. I didn't want to go too far, so it took a couple of meltings and adding a little bit more oil until I had something that was between the SPF and 50/50 hadness. I put them on the exact same bullets (358477), sized to the exact same size (0.358"), used the same type and amount of powder (6.2gr of HS-6), loaded in the same brand cases (Federal), with the same primers (Winchester). I shot five 15-shot groups with my K-38 from a rest, like I have done in the past.

The groups sizes were noticeably better than with straight 50/50 lube. Group sizes were 1/4 to 1/3 less than with straight 50/50 lube and were remarkably consistent. Interestingly, I saw something that I had never seen before. The front of the barrel had twice as many star-lube arms as I am used to seeing. All arms were very narrow. All were in the groove, but on each side and very close to the land of the barrel. There was absolutely no leading.

I am going to experiment with some other medium velocity loads. I also want to try this lube on the .357 Magnum. I think in that one it will be no better and might be worse than straight 50/50 lube. We will see, but I am definitely interested in pursuing this. BTW, I have tried some calculations on acceleration without success. Knowing the velocity at the muzzle and the barrel length, it is possible to calculate a constant acceleration. However, from everything I have read, this is not the way gunpowder accelerates the bullet. I also don't have any way to calculate the viscosity, but I can probably rig something up for comparison purposes so I can duplicate what works.

Has anybody else done anything similar to this?

[btroj]

I would be interested to see how temp changes the results. Do the results change when temp goes from 30 to 80?

Lube viscosity is a big factor. Mineral oil and vaseline are both good for changing viscosity, I view them as different melt temps of the same thing.

Interesting results, valuable info. Well done Harry.

[geargnasher]

http://castboolits.gunloads.com/showthread.php?148746-quot-Extreme-quot-boolit-lube-The-Quest

Yup, done a test or two. My premise before starting that little adventure was that the whole story to lube is lubricity and viscosity. Both have to be right for the application. I still feel that way. Lubricity is how slippery the concoction is, viscosity refers to how it flows when fired in the gun, something that's difficult to measure.

I threw out most of the lube pumping, inertial, or other theories on how lube gets where it does when I discovered that most of the time lube is blow around the boolit anyway, particularly in a revolver. Just monkey with it until it works and move on.

BTW, Dexron III, mineral oil, Vaseline, and paraffin wax are all paraffin-based stuff, defined by the molecular shapes. These can be used to harden or soften a lube without adding too much slippery effect. Harder, more "dry" lubes can be made using small amounts of napthenic oils such as engine oil or most common chassis greases. Too much of the latter, though, can cause slippery, erratic barrel conditions.

Gear

[Harry O]

Sorry, I haven't done any tests in cold weather. Everything is at room temperature (even shooting at an indoor range). The only way to learn anything is to vary one thing at a time.

I have used vaseline in the past to thin things. I used mineral oil this time because I wanted to alter the properties of the 50/50 lube as little as possible. The mineral oil, being liquid at room temperature, took very little to thin out the 50/50 lube.

[btroj]

Yep, even 5 percent makes a big difference.