2 coats of PC better for higher pressures?

[popper]

For us non-glock people, post the cal, not the gun model. My comments didn't apply here.
light gray/almost white looking residue -- I've seen that also. But also had some actual leading near the muzzle. I've recovered some bullets, PC is white, was HF RED IIRC (40sw). Abrasion of the PC in the barrel may scuff off enough to cause leading. I do see some 'smoke' from rifle shot on sunny day that isn't powder smoke, more like lube smoke.

[DougGuy]

Ok.. Your barrel throat, err lack of, could be the immediate problem. If it is shaving PC because it has no freebore, OR what little freebore it has isn't anywhere near .402" then you are firing rounds through another sizing die, this one with rifling. The bigger you go with boolit diameter, the more of the coating gets shaved off. If you were at .401" or even .400" before coating, then the coating would not be shaved off nearly as bad.

[Hickok]

In my Glock 20, 10mm, 4.5" OEM barrel, I use the Lee 401-175-TC, 50/50 COWW-PB +2% tin, PC'ed with Smoke's John Deer Green, sized .402" and a near max. load of Bluedot powder. Getting about 1250 FPS.

Works great in my Glock.

Maybe the Bluedot powder being somewhat slow-burning rate helps prevent leading....?

[Tripplebeards]

Guess I need to get a .401 lee sizer die and find out. Figured the extra 1000ths of clearance would help with accuracy and not leading my bore. I will hopefully get a chance to put another coat of PC on my boolits this afternoon, not re size and load load up with green dot. I’ll try some with green dot and not re coat. I will run some swabs through my bore with mothers polish to try and polish up the bore in case there are any sharp edges. Worse case scenario I’ll have to buy or borrow a wolf barrel and try it with the same loads.

[Smoke4320]

I would try .001 larger in bullet dia FIRST ..

[reddog81]

10mm isn't really pushing the limits of cartridge pressure or velocity so one coat should work just fine. PC works fine for 44 Mag, 460 S&W, .30-06, etc. I've recently been working on 450 BM loads with a 350 grain bullet going 1,400 to 1,500 FPS and don't get any leading in a 16" barrel. I shake off as much excess PC as possible and try to make the PC coat as thin as possible.

Why are you baking at 445? I thought 400 to 420 was generally the recommended range.

[Tripplebeards]

Did an experiment with my conventional oven years ago. The PC baked evenly the best at 445 degrees. I tried fem 400 degrees in 5 degree increments to 455 degrees. No slumping. I bounced off the excess each time before baking as well.

[Tripplebeards]

I finally had a chance to add a second coat of PC this moring. I measured a half dozen and they all were pretty consistent at .404". So they all grew .002 with the second coat of PC. I will load them up next week and report back to let everyone know if they leaded or not. Wish the extra coat of PC would have only increased a .001 th bigger instead of .002. Well, the largest measurement I took around my slug was .401. The rest of the measurements were .4005 and one at .400. So imo I'm approx .003 over with the .404's. Guess we will see what happens. I am testing the 11BH and 12.5BH alloys again.


If this dosent work I'll order a .401 sizer and cast up some harder alloy boolits to try. Will defeat the HP purpose as they will never expand then. Either that or I'll have to get ahold of a wolf barrel. Hope it won't get to that point. I have an extra one of these molds I'd trade for a barrel if anyone has an extra lock 20 10mm aftermarket barrel

[Smoke4320]

I do not believe harder alloy will NOT solve YOUR problem with the PC . There is something going on to remove the PC before it gets to the end of your barrel
Weather thats a sharp edge on your throat or cutting the pc when seating the bullets or another issue I dont know but doubt its a hardness issue

[charlie b]

...Either that or I'll have to get ahold of a wolf barrel. Hope it won't get to that point...

Before you do that you might want to send your barrel to Doug for throat work. Send him a PM and see what he thinks about this.

[Tripplebeards]

I still haven’t had a chance to shoot the oversize Boolits yet. Don’t know if I will now till after Christmas time just depends on how bowhunting goes. Most of my free time will be spent in the woods starting in about a week until I (hopefully) get a big buck. I kinda put the project off for now and started some remodeling projects. Might have to take a quick break and try some.