Leading with Hi-Tek Coated Boolit

[Xae289]

Hi there! I've been lurking for a long time and gathering up info from the experienced cast bullets shooters here. I had an experience I thought I'd share in case someone can educate me as to what's happening and maybe it helps someone else.

So I've been using Missouri Bullet Co Hitek coated cast bullets (boolits?) as long as I've been reloading, which is several years now. I've used them in .45 Colt, .38 Special, and .44 Mag with no more than mild leading and only in the .44 Mag so far. I just found out the Hitek coating isn't foolproof and it's possible for them to lead badly. No knock on the company because all the other bullets I bought from them have worked with no noticeable leading in my other guns.

The revolver is a S&W 629 Classic 5" barrel. I've slugged it a few times and there's definitely some amount of constriction where the barrel screws into the frame. To measure the bore's relative size, I took each slug, oiled it, and the slugs all pushed through each cylinder throat with light finger pressure. I bought pin gauges and the largest that fit all the cylinders is a 0.4295"(-) gauge (I didn't buy a + gauge in that size). The 0.4300"(-) gauge doesn't fit any cylinder.

I recently loaded some 240 grain SWCs from Missouri Bullet Co in some hot .44 Specials (~1050 fps) using Longshot powder. After 50 rounds, my accuracy went from great to poor. I thought maybe it was just unusually early shooter's fatigue, but when I got home, I found some of the worst barrel leading I'd ever seen. I've gotten some mild leading in that revolver using MBC's 300 grain WFN "Hammer" bullets, but never anything like that. I was able to use a pick to lift a ribbon of the stuff out of one groove. It started just after the frame and left long streaks out to the muzzle. It took a couple of hours of scraping out lead with a Choreboy wrapped brush and then some JB Bore Paste to get the bore smooth and shiny again. I loaded up some of those boolits and pulled them to make sure I'm belling the case enough not to scrape off any coating while seating them.

In any case, I bought a 500 bullet box, so I wanted to see if they were salvageable. I wasn't going to use them if they left such heavy leading. I'm not sure what caused the leading, but on a hunch after a lot of reading, I made lube out of ~60/40 beeswax and petroleum jelly, and pan lubed (very messily) a batch of 50 of the Hitek coated bullets. I couldn't find any source saying you even could lube any Hitek coated bullets, but it worked and the lube stuck. I repeated the same load, got no noticeable leading at all, and the cleaning was quick and easy.

My guess is that the bullets were oversize for my cylinders' throats by about 0.002" ( boolits measured 0.0015" with a caliper zeroed on the 0.4300 pin gauge). I know my barrel has a constriction. So my guess is that I lose some of the coating at the throat. Then they're shrunk even smaller at the constriction and can't spring back fast enough to seal the bore after it, leaving the bad lead deposits from the frame all the way to the muzzle. My guess is that the lube fixed it because it's viscous and flows under pressure to seal the bore after constriction in a way the Hitek coating can't.

Does my guess make sense based on the info I laid out, or might there be something else going on?

[Stephen Cohen]

Have you tried the smash test which is hammering a projectile with a hammer on an anvil, the idea being to see if coating flakes off in which case it is a faulty batch of cast. I only ever managed to lead a barrel on my 375 rifle by shooting undersized cast. I no longer load for pistol myself although I do supply coated cast to friends who do and they have never had the issue you describe, I load for rifles in 357 mag 357 maximum and drive 158 g Lee r/f with no check at 2,300fps and have no issues and great accuracy, I have even driven 125 gr Lee plain base at 2,700 fps to test the coating and got no leading and no accuracy at all. I load for 458wm and all is good and my brother shoots his SW460 Revolver at near 2,000 fps with outstanding accuracy and no leading at all. I would think that the problem is with the constriction you speak of, or a bad batch of bullets. We do have that problem here at times with commercially available Hi-Tek coated cast. I would do the smash test just to prove that the cast is or is not at fault. Regards Stephen

[Xae289]

Thanks, Stephen, I'll go ahead and do a smash test when I have a chance to see if it's an issue with the bullet.