My CED M2 chrono hates Tool Blue PC

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Skyhawk

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I was out yesterday again trying to solve my tumbling 9mm bullet problem. Nice sunny mid-afternoon, sky screens were on the chrono. Not a single PC'd bullet registered properly on the M2. Either they wouldn't register at all, or would give a crazy high reading like 6500 fps! LOL

The same bullet in bare lubed-lead registered every single time. And I shot a dozens upon dozens of each over that chrono, even alternating between bullet types. And trying distances ranging from 7 feet to 17 feet. So today I'm taking a black sharpie to my Tool Blue bullets in the hope I can chrono them and get to the bottom of my tumbling issue. I've tried upping the powder charge, pulling bullets to ensure the crimp die wasn't swagging, trying different seating depths, and sizing to .358 (after PC). Still 1 in 10 keyholes no matter what I do. Not one of these bullets in plain lubed form have ever tumbled, also sized to .358.

I did manage to recover a couple bullets from the berm yesterday and they look fine to me. I just wish they behaved!
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that's a new one for me, prob. hundreds of reports over on CastB of folks chrono'ing rounds with PC coating and I have never read anyone having the problem you are having...that would be a "puzzler" for sure.

The two slugs you have in the photo, were they shot into the same backstop medium, there is considerable difference in deformation...are all the bullets you have used in your testing being cast from the same melt/alloy/temp. The photo suggests that maybe one slug was considerably softer than the other which may be causing your "wobblers".
 
fingers284 said:
The photo suggests that maybe one slug was considerably softer than the other which may be causing your "wobblers".
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The backstop medium is a mixture of sand and rocky mud. I was lucky to find that intact one that somehow missed the rocks and debris. The lead is just clip-on WW alloy that I melted in bulk, made into muffin tins, then randomly add to my pot whenever I need topping up. There is a chance one muffin ingot alloy might differ from another because my stash represents many years of collecting. But I doubt it would make too much of a difference when firing subsonic rounds (aiming for 830ish fps) from a handgun.

The only other time I had occasional keyholes was with tumble lubed bullets from the TL356-124-2R. It also leaded my CZ barrels. It's why I got rid of it and jumped on the Lyman #356637 which dropped bullets .002 larger (.358) with my alloy. Now it's been years and years since I've seen a keyhole in a target, until now. At least the leading isn't back!

One factor is that I'm sizing AFTER PC using a Lee .358 push through sizer. It seems to size down to .3575, half a thousandth's smaller than my Lyman lube sizer. But I'm not sure that would make that much of a difference. I'd like to try them unsized, but with the PC coat the bullets measure .360 or a bit over and they fail the chamber fitting test using what I'd still consider a safe seating depth. I find it interesting that the recovered bullets do seem to be engaging well with the barrel rifling with no visible signs of gas cutting.

I'm very stubborn (just ask my wife!), so I'm not ready to give up yet.
 
hometownhero said:
I have shot a lot of coated cast over the screens and always got a reading. Tool blue is no exception. I am not sure why the are not registering for you
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Maybe the conditions were that the bare lead just worked while the tool blue didn't. I have a bunch loaded now that I coloured black with a marker that I'll be trying out tomorrow. I think conditions tomorrow will be mostly overcast but bright. We'll see how it works.
 
I sometimes get no readings from my chrony with plain cast bullets. When that happens I remove the sky screens and then the chrony reads normally. It has something to do with the makeup of the bullet's shadow passing over the sensors. Try your blue bullets without the sky screens.
 
I think I found the problem. I was able to successfully test a a a few strings of 20 without a single error or failure to register. When I did this the first time, there was still snow on much of the ground around the tripod, and puddles of water underneath... very sunny day too. The difference with my PC bullets is that they're very shiny (high gloss) compared to the dull oxidized lead bullets. My theory is that light was reflecting off the snow and puddles back up to the underside of the bullets which confused the chrono as it passed over the one or both of the sensors. Winter is over (I hope) so problem solved for now.

I managed to also get all the bullets to hit the target nose first, and work up my load to consistently go just over power factor with a SD of around 16 for each 20 shot string. So much improvement, considering mixed head stamp reloads with home cast PC'd bullets. Turned out the PC bullets did need a bit more charge ... even at 3.1 grains of N320 perhaps one out of 10 shots didn't quite meet power factor. 3.2gr was the sweet spot. Bullets were all sized to .358" AFTER PCing, and I backed off the crimp die to basically not do anything. I shot over 500 rounds today without a FTF so my CZ's don't mind the swollen bullets.

What was really nice is coming home after 500 rounds to clean my guns with a half sheet of paper towel, and a single patch dampened with CLP for the barrel.
 
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