Awesome Case of Keyholing

[Reed]

This was the first use of my new Lee TL356-124-TC 6 cavity mould. As you can see, there are very few round holes on this target--mostly keyholes. After seeing the results from the first magazine, I went ahead and shot everything I loaded, not wanting to pull the remaining 42 rounds apart. There was no leading after 50 rounds. I certainly expected some.

Bullets dropped somewhat oval, the narrow side .356, and the wide side .358 ∓ .001. But then, most of my low-cost aluminum moulds seem to drop out-of-round by 2 or 3 thousandths, so I'm not sure how pertinent that detail is to this keyholing situation. I sized them using a .357 die. The bore slugs .356. There is no throat to measure. The barrel just begins after the head space shoulder. The alloy was 50/50 WW/PL air cooled for only one day. This is the first time I've used this alloy without heat treating it in my 9mm. Probably a very naughty thing. Muzzle velocity @ 3 yds was 921 fps using 4.6 gr Ramshot Silhouette. Just looking at Western Powder's low and high load data, I'm thinking pressure was somewhere around 29,000 psi.

I've shot this alloy air cooled in 38 Special loads at similar velocities. However, they did sit about a month before I loaded them, so I'd say they were somewhat harder by then. The 38 Sp is also a lower pressure situation.

I've used this same bullet design from a Lee 2-cavity mould for a few years with good results although in my 9mm this alloy has always been heat treated or I've used straight wheel weights. Past powder charges have usually been this same 4.6 grains, or sometimes even a bit more. My thoughts: alloy too soft for the pressure? Shouldn't have been in such a hurry to go shoot these bullets? Not sure why I didn't find lead in the barrel, though. I thought for sure with bullets flying willy nilly like this that the bore would be ugly.

Somewhere in my travels, I read a post by Ed Harris that 50/50 WW/PL with a pinch of tin should be BHN 8-10 air cooled. For a pinch of tin, I usually throw in about 18 inches of unidentified solder. These bullets filled out nicely with that.

Anyone have an idea roughly how long it might take this alloy to reach BHN 8-10? I was also contemplating what the hardness might have been after one day. Any thoughts/suggestions that might help me clarify my thinking? My thinking is I need a little harder bullet. Waiting only one day without heat treating won't cut it. Next step: wash off the tumble lube, heat treat this same batch, and try again.
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[quicksylver]

Need bigger bullets maybe .359

 

[Reed]

Need bigger bullets maybe .359

I wouldn't mind, but even .358 often doesn't always go into battery. .357 is about as big as I can go and reliably chamber rounds. I know the small side of these bullets is just at bore size at .356. With this mould maybe I can't get away with this alloy. My 2-cavity drops them around .357. I was thinking that at bore size, they might obturate and seal up OK. There is that school of thought that as close to bore size as possible is good. The other school of thought of course being that slightly bigger is better. I've never decided where I fall in. Still wondering about the softness. Will try heat treating before I abandon this alloy with this mould.

 

[quicksylver]

I have shot bullets cast t he same dsy with no problems what so ever...to me they do seem a little on the soft side ...coww+ 2% tin is always good..general consensus around here is THROAT size ....bore has little to do with choosing dia...except for nose size..

Might want to try a slower powder with those bullets...

I can duplicate that results in my 1917 Eddy stone with very hard bullets that are undersized....so can anyone else for that matter....

No leading interesting

Could try drooping the charge .2 grs

 

[RBHarter]

I get by with 50/50 in my 9s WC but I basically load until the group closes after function . That usually isn't far above start loads . I use 1-20 from tamper seals for the lead 50% and that may be coppered also in the cleaning melt process as they mostly have copper wire stems .

The 40 I loaded for had to have WCWW or it keyholed , period .

 

[9.3X62AL]

No leading could mean that the pressure stays sealed behind the bullets, but the bullet may still not be taking the rifling well. Most 9mm barrels run 1-10" or 4 turns/meter twist, which is insanely fast for the short squatty bullets we use in 9MM. Hard alloy/soft lubes have paid off for me with the 9mm, 40 S&W, and 10mm. I am NOT a fan of tumble-lubing, so no experience with that variable.

 

[fiver]

the BHN will take about 7-10 days to settle down and become fairly consistent across the batch.
you'd most likely hit about a 9 in that time.
on day one a 6 would be more like it.

key holing is a stability issue.
you either are not spinning them fast enough, or your not spinning them fast enough.
I'd go with your not spinning them fast enough.

if you could go pick one of the boolits up I bet you'll see a wide trough where the rifling cut an impression in the boolit about twice as wide as the actual rifling is.

 

[Ian]

Either water-quench them or find a way to cut the pressure in half. They're turning to putty and the bases are likely so out of square that the muzzle exit yaw would require a 1 in 2" twist to stabilize them. Or, they may be flat out stripping the land engraves by the end of the barrel and not even spinning. That would normally lead the bore, but with such a fast pressure drop and short barrel it can happen and you'll never know it by bore condition because the bullet sealed in the beginning when the pressure was high and linear velocity low.

 

[9.3X62AL]

Lamar and Ian gave much better explanations of the concept I was trying to relate. Thank you, gents.

I treat the 9mm/40/10 like a rifle, owing to the pressures involved and usual twist rates. My metal for these calibers is 92/6/2, which runs about 14-15 BHn. These loads are almost exclusively used for self-defense practice sequences and recreational plinking, so lack of expansion isn't an issue. 10mm could conceivably get some hunting usage, and if so I'll put up some Bruce B Softpoints for that purpose.

 

[Reed]

What an amazing amount of knowledge this group possesses. Everyone's comments were really helpful. Seems like a big vote for harder bullets, although the barely-at-bore size from this mould was was nagging at me. Thank you, everyone who's offered advice.

...to me they do seem a little on the soft side ... general consensus around here is THROAT size ....bore has little to do with choosing dia...except for nose size.. Might want to try a slower powder with those bullets...

Quicksylver, Your slower powder suggestion (from another thread you replied to) worked out really well in a PB 30-30 load I was having trouble with. I'd love to load for throat size--if this gun only had a throat.

I get by with 50/50 in my 9s WC but I basically load until the group closes after function . That usually isn't far above start loads . The 40 I loaded for had to have WCWW or it keyholed , period .

That's reassuring. Make 'em harder. I'm trying to conserve my WW by stretching it out with the considerable supply of PL I've ended up with. Note to self: Plan better. Quench, if range time is iminent.

No leading could mean that the pressure stays sealed behind the bullets, but the bullet may still not be taking the rifling well. Most 9mm barrels run 1-10" or 4 turns/meter twist, which is insanely fast for the short squatty bullets we use in 9MM.

9.3X62AL, you paint a good picture of what might be going on here. I wish I could have recovered one that day.

the BHN will take about 7-10 days to settle down and become fairly consistent across the batch.
you'd most likely hit about a 9 in that time. on day one a 6 would be more like it. key holing is a stability issue. you either are not spinning them fast enough, or your not spinning them fast enough. I'd go with your not spinning them fast enough. if you could go pick one of the boolits up I bet you'll see a wide trough where the rifling cut an impression in the boolit about twice as wide as the actual rifling is.

Fiver, thanks for answering my question about the BHN. Another vote for not taking the rifling well. Appreciate the humor about insufficient velocity. Note: make harder so I can spin them faster.

Either water-quench them or find a way to cut the pressure in half. They're turning to putty and the bases are likely so out of square that the muzzle exit yaw would require a 1 in 2" twist to stabilize them. Or, they may be flat out stripping the land engraves by the end of the barrel and not even spinning. That would normally lead the bore, but with such a fast pressure drop and short barrel it can happen and you'll never know it by bore condition because the bullet sealed in the beginning when the pressure was high and linear velocity low.

Ian, another great mental picture of what's happening to the bullet. Putty. Not spinning is a worthy notion. You should have seen the target backer. Many more holes some of them a foot from the paper.

Lamar and Ian gave much better explanations of the concept I was trying to relate. Thank you, gents.
I treat the 9mm/40/10 like a rifle, owing to the pressures involved and usual twist rates. ... Bruce B Softpoints ....

9.3X61AL, no, your explanation was good. I like your rule-of-thumb about treating 9mm like a rifle. That made me think about the twist in 38 Special: 1:18.75! No wonder softer bullets run better in it than in the 9mm. A little easier to follow the rifling down the barrel. You mention Bruce B. I've read some of his old posts. Wish I could have met him. I lived in NV when he was hosting his get togethers, but I wasn't into cast yet.

Again, thank you all. This is an awesome group.

 

[Ian]

It will take right at two weeks minimum to see 90% final hardness if you water-quench your current mix. The more tin you add, the longer it will take for them to harden, I would add zero, though they will cast small. Final hardness if you drop them instantly from a hot mould into cold water will have a compressive strength somewhere around 18-21 bhn, but will have the same deformation characteristics as it would in it's natural, air-quenched state. 50/50 lino/WW will have about the same BHN, but will behave MUCH differently in the way it deflects under pressure.

A good throating job by DougGuy might be in order, too.

 

[Winelover]

IIRC, my first attempt at using cast, in 9mm, was with the RCBS 125 RN GC in my HP. Was using Bluedot with Speer 125 RN J-words. So, naturally, I tried that first. Severe key-holing, at close range. Switched to Unique and it went away. Stayed with Unique, ever since. Alloy was air cooled. To this day I still use air-cooled in my 9's. The only other bullet, I cast for, in 9mm is the the Lyman 120 TC PB. Use either Unique or Bulleye. No leading or key-holing and alloy is air cooled WW approximation. Hardness is roughly 8-9 BHN.

 

[popper]

Might try ACWW only to get slightly larger boolits. Or try beaglng the mould. I got a few keyholes in 9mm with a hard alloy - never did find out why. Proper size, coated, etc. 1 in 10 printed a nice sideways print. Sure they didn't get swaged down in size when loading?

 

[KHornet]

I shoot that bullet with range scrap and a little tin, air cooled, running about 12BH.
never had any problem.

Paul

 

[fiver]

Brad has a thread here somewhere dealing with his 9mm.
he and I shoot the same guns, using the same mold, and the same powder.
we also use basically the same reloading press, and range brass.
our alloy is fairly similar but I add a little lino-type and air drop and he tried matching my alloy.
I know we even used the same basic lube a time or two.

but he had leading and I didn't have any.
when he looked at his throat it was obvious what the difference was.

 

[Reed]

More good info to think about. I feel like it's my birthday! Thanks some more, you guys. Good info for my notes on alloys and BHN. Probably won't get any throat work done, though. Fixed retirement, blah blah blah ... Popper, I haven't pulled a bullet to measure, but I don't think these bullets are getting swaged. There's no visible bulge when seating the bullet. I'll pull one and measure it, though.
Winelover, I like Bullseye and Unique, too. Here's a group using 4.6 grains Unique with ACWW, 25 yd. Bullets are flying pretty straight, although I do see that one side of the holes has a darker, thicker smudge line. That might indicate a little wobble, aye? Max spread is 3.7". Three inch barrel.
And one w/ 4.8 grains Silhouette with ACWW at 25 yd., also flying fairly straight. I'll admit the other 3 holes were off the paper. Of those 5, the max spread is about 3.5". I didn't scale these pictures very well, but the distances to the targets were the same. The little gun shoots good enough with WW and most powders, including Bullseye, Red Dot, and 700X. I just had a really good buy on Silhouette a few years ago and try to use it when I can. That stuff meters really well. Other goal is to try and use up some of my PL. Might have to get some black powder firearms to help with that!

 

[freebullet]

I've shot nearly pure in 9mm without issue.

You can beagle the mold to get it casting round bullets.

Try 3.8 grains of titegroup or red dot.

Looks like you have a possible lube purge issue.

 

[freebullet]

I have a 35 cal pistol throating reamer. If you want it done & are willing to cover shipping to & from I'd throat your pistol barrel at no cost.

 

[Reed]

I have a 35 cal pistol throating reamer. If you want it done & are willing to cover shipping to & from I'd throat your pistol barrel at no cost.

That is a truly generous offer. It's my carry gun. If I can arrange for a substitute, I'll PM you and talk about some details. Thank you, freebullet!
Re the possible purge issue: Are you thinking the circles around the bullet holes are from lube, and not from the lead?

 

[Winelover]

Looks just like all my bullet holes from non-SWC'ers. Rifle bullets holes, look the same on my cardboard backed targets.....at times I have Carnuba Red splattered on even the 100 yard targets.