Lube build up in chamber w/ FWFL in 10mm loads

[Elkins45]

I'm trying out a boolit I designed for 10mm. It's a 200 grain wide flat point and I'm trying to drive it as fast as I safely can. I cast some with ACWW, lubed with Felix lube and sized them to .401. The load I'm using is load book max for AA #9 w/ a 200 jacketed.

I'm having reliability problems because the lube is building up in the chamber after only a few rounds, preventing the slide from closing fully. When I pull the rounds there is a gummy ring around the case mouth. Once I scrape it off I can rechamber and shoot. Accuracy is fine, but the gummy mess in the barrel is a problem.

Any suggestions other than the obvious one of removing the Felix lube and trying something else? And why do you think this is? I don't have these problems with my rifle boolets using the same batch of lube.

[felix]

Viscosity is too high (or lube too heavy) for THIS pistol application, it appears by guesstimation. Try thinning and report back. Other ideas welcomed from our current experts generating new formulas. ... felix

[gwpercle]

Use less lube? If they are already lubed maybe wipe some off?

[btroj]

To test what Felix is describing you could melt down a. Bit of the existing lune and add a small amount of Vaseline. That will make it a bit less viscous. The fouling may still be present but it will be lighter in texture and shouldn't keep the slide from going into battery.

I find it odd that this happens at all with Felix lube. I have used it in many guns, it always leaves a bunch of fouling but it is always of a nature that it doesn't Affect functioning. Makes me wonder if something else isn't happening at the same time.

[runfiverun]

another cure might be a bit more crimp.
I know it sounds odd.

[Elkins45]

another cure might be a bit more crimp.
I know it sounds odd.

No, it really doesn't. I've considered this as a possible next step. The barrel in question has a particularly tight chamber anyway, so loads that function well in my other 10mm pistol can give problems with it. I always try to use the minimal amount of crimp possible when loading boolets, but too little seems to be just as bad as too much.

I think I will try both approaches (a batch with more crimp, one with different lube) and see what factor makes the most difference.

[geargnasher]

FWFL, really slow pistol powders, and boolits that obturate the bore quickly is a recipe for chamber fouling a short-throated automatic. Lower viscosity per Btroj's recommendation (2-3 TBS per pound of lube), force chamber pressure up inside the case before boolit release (more crimp or try AA#5) for a cleaner burn and better chamber purge when the breech unlocks and the case begins to extract.

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