9mm Coated Bullets Leading

bilbo

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I've used 'Blue Bullets' coated bullets for a while and had a good load for plinking at the target range. It was 3.8 grains of W231 and a 124 (125 maybe?) grain truncated cone bullet. Earlier this spring I ran out of bullets and couldn't get more due to COVID, and went looking to see if anyone was still shipping in a normalish timeframe. I ended up with Ibejiheads 125gr. TC bullets and loaded a couple up with the same settings as the blues used. The bullets must be shaped slightly different and I had issues with clearance so had to seat them deeper, by about 0.030". I had some leading issues with them and thought it was due to deeper seating and increased pressure/velocity. The bullets were also sized 0.356 vs. the blues at 0.355.

Anyway, after getting all of the leading cleaned out (took a while), I loaded up some more at 3.7 grains of W231 and after 50 rounds I clearly still had leading issues. Even after 10 rounds I could see the white showing up at the muzzle. I figured my crimp must be the cause; I have the Lee 1000 so only three stations. Seating and crimping is one step. I loaded up a few more and pulled the bullets, but found no damage to the coating or bullet deformation. I didn't see a difference in size, either. I stepped down one more tenth of a grain for powder charge and made another 50. Still had the same issues. The minimum listed data I found lists 3.9 as a minimum load so I'm not sure going lower is the answer.

From what I've read, about all that's left is the bullet's too small and the combustion gases are cutting around the bullet, burning coating and melting lead. Which is weird because the Blues are smaller and don't have any issues. I know I can just go back to the Blues (I do have some now), but I'd still like to know what the problem here is. Any ideas? I haven't been able to find any reports that Ibejiheads are poor quality. Quite the opposite, and they do appear to be well made, so I don't think I'm ready to write them off yet.

Another possibility I remember reading about is if they are hard enough, the cast bullets won't handle light loads as there's not enough pressure to initially deform the base of the bullet and seal it to the barrel. So maybe a hotter load is the answer?
 


lazyMlazyK

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Granted I'm just getting in to casting, but if it were me, I'd start out by running a little hotter if you can, or possibly trying a faster-burning powder. I'm betting you're not getting full obturation.
 

bilbo

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The data from Hodgdon says 3.9-4.4gr is the range for W231 and 125gr TC bullet. I’m going to try out 4.2gr and see what it does.
 

bilbo

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I tried 4.2gr charge and it was noticeably more snappy, but still the same leading issue. I'm stubborn and not ready to give up yet, so ordered a sample pack of .357 bullets to try. If they work fine, it must just be the size combined with hardness or something. I still haven't tried different powders but may give that a shot later. I have some Titegroup; I believe that's a pretty fast powder.
 


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