Is my alloy telling me something?

[RedHawk357Mag]

So I built a new lead catch trap and I captured all fifty of the bullets. Test was ten rounds of five different powders with the Noe 360176 SWC. Alloy is hand sorted COWW or same with additional tin up to around 2 percent per Bumpos alloy calc. Target is pizza box cardboard, moderately thin resilient plastic sheet and rubber mulch. I normally don't get to see fired bullets in such good condition as my previous bullet trap is logs shot into the end grain. My bullets are normally heavily abraided when I eventually get around to recovering. What happened to the lube grooves? Appreciate it. Have a great day.

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[bazzer485]

Dunno about the grooves but clearly your pc isn’t stayin on as it should. Have you tried the smash test on the coated bullets? What the velocity your shooting?

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[RedHawk357Mag]

That's the good side lol. With same bullet lubed with Blue Carnauba velocity is 1100 and under. Haven't chronographed the same PC loads. I did smash and rub test with Xylene and both performed as expected. I had some fouling with this fifty but it didn't take anything more than six patches with two separate brass brushing to remove. Typically takes two patches with other gun and PC bullets. But this gun and bullets definitely had more fouling. I posed a question on PC sub about PC fouling.

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[Rcmaveric]

The obturation is to be expected. As long as it is accurate and doesn't lead I wouldn't worry about it too much.

Your alloy is telling you it's obturating and make a good bore seal.

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[bazzer485]

I don’t have any to hand, but on my 10mm at similar velocities, or maybe higher, smokes powder or the Hi Tek I am now using stay near 100% intact, the coating that is. I wonder if your coating is coming off in the bore or when the bullet hits the target. Maybe try shooting into water.


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[Bookworm]

Your lube grooves are getting smushed forward by the pressure of the burning powder behind the boolit. As the lead cylinder obdurates (expands under pressure) to fill the available space (the barrel) the lead has to go somewhere.

You have to remember - at some point in the firing sequence, the rear of the boolit is moving, but the front of the boolit isn't moving yet. Just the opposite of the boolit mushrooming when it hits the target.

[Cosmic_Charlie]

The obturation is to be expected. As long as it is accurate and doesn't lead I wouldn't worry about it too much.

Your alloy is telling you it's obturating and make a good bore seal.

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^ What he said.

[Cosmic_Charlie]

I was thinking of batching some 95/2.5/2.5 to try in my 357s for medium loads, but just with BLL.
Nice looking PC btw.

[Misery-Whip]

I also fire into rubber mulch. I get similar looking boolits with smeared lube grooves. The rubber is dense so not only is the bullet being defomed on firing but again when it stops in the mulch.

If the load is accurate, i dont worry about it.

[RedHawk357Mag]

Appreciate all the responses. I was just surprised that nearly all all lube grooves were collapsed, except one load apparently. As for the PC, that side is the pretty side the other side is coyote ugly. The top three bullets were the only ones that maintained PC somewhat completely. I either damaged the PC on bullet seating or the bore damaged the coating or combination of the two.

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[bazzer485]

Nothing wrong either bullets getting squashed like that and the grooves being deformed. But I say again your coating should not look like that at all. It should be nearly 100% intact, it’s coming off somewhere and if it’s in the barrel I’d check for leading.


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[Silvercreek Farmer]

Accuracy is all that matters. If you need accuracy for 1,3,5,50,100,500, or 1000 rds, then so be it. Don't go looking for a problem.

I pulled some PCed boolits a while back and was shocked to see a damaged coating (insufficient neck expansion?). But they shot fine, so no worries.

Just like lube, I think the first few rounds of PC lays down a layer that conditions the bore. Once conditioned the bore will tolerate less than perfectly coated boolits.

[44magLeo]

Could be the bore I that gun is a bit rough and shredding the PC. With a smooth bore it shouldn't take more than a tight p[atch to get most of the crud out. A second gets the rest.
At least I my guns with conventional lube. I don't PC. Yet.
Leo

[RedHawk357Mag]

Did some further testing yesterday and it's looking as it's my seating of the bullets causing the issues. Fired the same lot of bullets in three different loads in a different gun with much better results with some loss of PC. I knew I had nicked a couple while loading. The resulting fouling was as expected and easy to remove from both guns. Ran 25 rounds of a different loaded bullet, same PC process, again with some bullets catching a nick in coating during loading. The PC on a couple bullets was worn in spots. Fouling wasn't difficult to remove. I think the reason the fouling isn't difficult to remove is because it's cured properly and it doesn't adhere to the barrel like the under cured PC I have read about here and there.
I believe that I was expanding just a bit too much and during the bullet seating the occasional less than straight seating of a bullet was just catching on edge of the brass as the brass was going into die and the brass was being closed a small amount as it was moving through the taper of the die. I could just feel the minor difference of the smoothness when a bullet caught on the brass. It would also cause a thin piece of PC coating a little thicker than a hair to be deposited into the crimp groove. Reducing the amount of expanding and giving the seating die an additional turn of clearance should clear the scraping up.

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[RedHawk357Mag]

The first thirty same bullets, different gun, loaded with additional emphasis on straight alignment in the case. The unfired bullet is a pulled bullet from a split case I found when loading the cylinder. The 50 are 358 150 SWC KTs fired from both guns 25 apiece. The unfired are original examples of the bullet.

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[kevin c]

That's a really impressive demonstration of bullet upset!

I'm fairly new to this. Could some of that be terminal upset, even using a forgiving target medium? I can see that the marks from the rifling in the lube groove, which I think shows initial upset in the leade and bore, but could the changes in the crimp groove and ogive be from hitting the target?

[RedHawk357Mag]

On the 358 150 SWC KTs picture the bottom row of black PC bullets 1 and 8 from the right I believe hit my front plate retention block. It's 1x2 pine. That's actually the very first time shooting the KTs. They are the same COWW as the 176s. I believe the KTs were shot at a lower speed than the 176. KTs were 6.8 of Ramshot Zip. The 176 were 7.0 of Unique, 4756, and Herco. Bottom left of the picture you can see the two strikes. The KTs strike considerably lower than 180s and 200s. That's 130 strikes on my front plate, still 100 percent retention of the mulch.

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[Forrest r]

The lube grooves are supposed to compress (collapsed). When they don't that's telling you that your alloy is too hard for the pressure of your load.

Extreme compression:
A 8/9bhn hp hb swc in a 44spl case with a 18,000+psi load.
[IMG][/IMG]

A side view of the compressed hb body