Corn starch lube experiment, round 2

[Elkins45]

This thread is a follow up to this post:http://castboolits.gunloads.com/show...=1#post2663784

I tested round two of what I'm calling my "Kentucky Fried Gravy" lubes. As per the previous thread, I mixed my two lube formulas together and tested a longer series of shots. The boolet and load are the same, the only difference being the lube. Temps were in the low 40's this evening and the gun and ammo had been in the weather all day.

I had a box of 50 rounds and began by firing two fouling shots. I then shot two groups of five shots. I let the rifle cool and fired two more, then repeated until I had fired eight groups. The last 8 shots were sort of a "mad minute" after shooting the 7th and 8th groups. I was aiming at the staple at the bottom of the target. As you can see, my last fast groups were as good or even better than the first. The rifle was not cleaned during all 50 shots and there seems to be no visible leading. I think the fliers are my poor trigger control and not the result of the lube...I think.

The targets:



I think I might be onto something here, but I still can't say I'm a big fan of the handling qualities of this stuff. It's gooey enough that it behaves more like straight Vaseliine than it does a wax, and it would be difficult to store lubed bullets without them pulling the lube out of their neighbor's grooves. The next step in experimentation will be to try to improve handling qualities by either adding more starch or maybe dissolving the whole thing in some beeswax. I'm reluctant to try anything that requires adding heat for fear that it might 'cook' the starch and inhibit the stop leak qualities it seems to be exhibiting.

[geargnasher]

Please refresh our memory on gun, load, boolit, range, and est. velocity? I mixed up a batch of ester oil and cornstarch the other night after you posted the first thread and hit the wear tester, I was NOT impressed but then again, it doesn't mean much.

One of the best groups I EVER shot with my .270 was with a microwax/atf/powdered Viva paper towel lube, but I only loaded five and next round at the range was unable to duplicate it. Yours looks very consistent, start to finish and repeatedly. If any anomalies were to show up they would have done so within 20 rounds.

Gear

[Elkins45]

Gun is a Marlin XL7 rebarreled with an Adams & Bennett 35 Whelen barrel. Load is a 230 grain ACWW NOE 358318 HP in front of 21 grains of 2400. I would guess the velocity at 1700-1800 fps, extrapolating from Lyman data for the 358 Win, but I didn't chrono it to verify. Range is the same 75 yards as the first test for consistency.

I don't think the rifle likes this boolet as much as the regular 200 RCBS but I didn't have any of them that aren't already lubed. I think I will crank out a batch of them before my next test.

[runfiverun]

I think cornstarch sees slightly higher temps when it's used to make gravy than it would see being added into melted b-wax.
I'd have to not add the b-wax except as a bump to what you have now, not as an over the top carrier.
you'll change the whole composition.

[Elkins45]

Yeah, beeswax isn't my first choice. I think just upping the corn starch percentage is the first thing to try.

I'm very pleased with the performance in the gun, just not handling/storage properties. My gut feeling tells me there's a sweet spot where it will have a more conventional feel but still retain good performance. I think the range of proportions is probably pretty narrow between too much like powder and too much like goo.

[375RUGER]

Your starch will hold the oils nicely if a bit of heat is applied to the oils and then mixed in. I melt oils and add the starch at less than 150*F. I like arrowroot starch better for bonding/holding the oils(better texture), you might think about trying that sometime. I'm not using it for boolit lube so have no advise for that. A bit of beeswax will firm up oil/starch mixtures in a hurry.

[waksupi]

I would bet on a real humid day, you will see more bore fouling with corn starch.

[Elkins45]

I would bet on a real humid day, you will see more bore fouling with corn starch.

Well, that will certainly be easy enough to test this summer. There's never a shortage of humidity here in July and August.

[badbob454]

question , why cornstarch is it the property of being hard when hit but soft when pushing slowly ,? how did you come to the conclusion of using it , will starch lube better than say flour? , this is the first time i have heard of this , so i am curious ....i can see where this may work good with lee alox , may stiffen it up some and my be not as tacky...

[Elkins45]

question , why cornstarch is it the property of being hard when hit but soft when pushing slowly ,? how did you come to the conclusion of using it , will starch lube better than say flour? , this is the first time i have heard of this , so i am curious ....i can see where this may work good with lee alox , may stiffen it up some and my be not as tacky...

I was thinking in response to something Gear had posted, in conjunction with Fryxell's stuff on the LASC site about what lube actually does. One of the main jobs of lube is to prevent flame cutting by hot gasses from advancing past the bullet base. Something in my head made me think about the Stop Leak products sold for car radiators, or Slime for leaking tires. Essentially (at least to my naive understanding) they work by plugging up the leaks with particles forced into the holes under pressure.

My thinking was "why wouldn't that work for bullets, and what would be a common substance to try?" Corn starch came to mind because it is cheap, readily available, extremely fine, not abrasive, and fairly compatible with oils or other lubricants. The starch in my lube mix is intended as both a carrier and an active ingredient. The Vaseline gives it fluidity so that the tiny particles are free to flow into the leaks as they occur. In a perfect world the particulate used in this sort of lube would be completely inert. The fact that corn starch is flammable might become an issue, and knowing that is fairly hygroscopic is probably what led Waksupi to predict fouling in humid weather. My hope is that the oil saturation will tamp down the absorption of water from the air, but that is an unknown at this point. It is clear from the smell that at least some of the starch is burning, but I don't know if the combustion is happening in the bore or primarily in the muzzle blast.

Experimentation is fun, even if it ultimately ends up being a failure. Frankly I'm a little surprised it even passed the first trial.

[btroj]

Hats off Elkins. This is the sort of thing that advances knowledge. It may not pan out but we learned some stuff we didn't know before.

If you add wax add as little as possible to just increase the viscosity and I prove the handling aspects of the lube.

[geargnasher]

Elkins, I am surprised too. I had much the same ideas as you on this, and wrung it out pretty well in the Extreme Lube thread. The one thing I didn't try for a carrier was wood flour, and one member from Florida had offered to send a sample for testing, but by that time I had given up on it due to the smearing/leading/fouling problems. My theory was that, since lubed paper jackets work so well, why wouldn't paper dust filler work as a lube base? It should slide against the bore no problem at high velocity/pressure, it shouldn't stick, and will hold oil well. The lightbulb came on one day and I started trying a super-refined baker's flour, then tried regular flour, cornstarch, Metamucil, and finally paper towels that were powdered to dust in a blender. The powdered paper towels needed a small dose of wax to bind into a lube, but flowed well and would work no problem in a lube-sizer.

Now my lightbulb is coming on again, I'm thinking TnT with cornstarch or possibly giving the microscopic wood flour (epoxy thickener for boat repair) a go. Even #2 grease is fortified nicely with the addition of cornstarch....but hey, those results posted here already are looking way better than anything I came up with.

Gear

[runfiverun]

gypsum is still on my list...
super easy to get too.

[Elkins45]

Under heat gypsum decomposes to plaster and water. That might make some interesting fouling.

[runfiverun]

only one way to find out....

[BABore]

Have you guys tried mixing in motor mica?

[runfiverun]

I have been using motor mica [and colloidal graphite] to bolster my over the top bens red, and it goes in the OD series of lubes as an additive.
but as a main ingredient not yet.

[Elkins45]

Motor mica isn't cheap. As a primary ingredient (like the corn starch in this experiment) I think it would get expensive pretty fast. Midway wants $10 for four ounces of the stuff.

Gear, I don't know what TnT is.

[runfiverun]

TnT stands for thick-n-thin.
I'd have to go back and look at the oil that was used [a 2 stroke airc]

[leftiye]

If motor mica is expensive (and has its own oil?), why not powdered graphite, MDS, or HBn? I know that in the current theory, that true lubricants aren't the vogue, so this may or may not be an improvement. A little paraffin, or other grease added to, or instead of the oil might work well too in the present concoction as thickener.

Alternatively, as per the Jim's "Black Majic" graphite lube, use graphite (probly with grease to hold it together) instead of corn starch?

As an after thought - This reminds me of Glen's version of Lithi bee where he uses Sta Lube moly/graph grease. Maybe just use a lot less oil/grease?