9mm bullet tumbling at the target. Some suggestions?

[Proudprado]

Please help if you can:

I'm casting and powder coating for 9mm Luger. I'm using the 6 cavity Lee mold, .356 125 2r. I size the PC coated bullets on a .356 Lee sizing die. At the start of this process, the bullets were performing very well. I was using range scrap for raw material and I loaded the completed bullet to get around 1040 fps, easily making IDPA factor.

After shooting around 5000 bullets, I bought lead from a new source ... already mixed with tin and antimony. I think everything went OK with the first ones, but suddenly, at a recent tier 2 match, my bullets started tumbling. About two to five in every 100 shots. It seems more obvious at shorter ranges, which has me stumped.

After reading the posts I could find here on tumbling bullets, I stopped sizing and simply loaded the PC bullet. While the completed round now stand slightly proud of my case gauge, it does chamber. Yesterday I fired 25 shots of the larger diameter bullet. 1080 fps and almost all of them tumbled. Even at 25 yards.

The only difference I see in the bullet is a slight mark on the base. The first batch of lead seemed smoother.

It does have an effect on accuracy (rounds go low) and I'm not sure how to proceed. I'm shooting a big match on Saturday and, for the moment, I'm going back to sizing the bullet to .356.

I'm shooting a Glock 17 Gen 4. I clean the barrel after every session (around 125 to 150 shots). There is no leading that I can see.

[Willbird]

I'm at the same place with that bullet. I'd suggest seating and pulling one, and measuring before and after to see if the bullet is getting sized when it is being seated.

I worked on my expander plug size to end up with a case .002 smaller than the bullet, that stopped the swaging while seating issue, when I started I had a case mouth that was .351 inside and a bullet that measured .358 before seating and the base was .353 after seating.

My Lee .356 sizer sizes a bullet to .3555".

Once they start tumbling accuracy leaves the room for sure IMHO .

I am working with the 120 TC bullet now....still seeing leading but seeing decent accuracy at 26 yards after 64 rounds fired. My gun is a 3" XD9 double stack.

Bill

[ioon44]

"when I started I had a case mouth that was .351 inside and a bullet that measured .358 before seating and the base was .353 after seating."

I had this same problem when I started loading 9 mm, I had to change to different dies and larger expander with harder bullets.

[asmith80]

If you're using a lee powder through expander you can swap out the expander with one for a 38 S&W. That fixed my swaging problem.

[marek313]

Couple things to consider here.
I had to open up multiple Lee sizing dies before I got size I wanted and your die probably sizes to .355 which is really small for cast lead. I size my 9s to .3575 and many go even larger but that would depend on your gun.
Use larger expanders to make sure you dont swage your bullets while seating.
Your new batch of lead might be softer then your previous one which would swage those even more when seating. Try water quenching to gain few BHN. I also wait at least a week after casting before I load my bullets to make sure they gain full BHN before I use them.

[Dragonheart]

I would suspect you have a bullet problem, but there could be other things in play. I don't know where not sizing PC bullets came from, but that is the first place I would start. When a cast bullet comes out of a mold it is not round and PC does not correct this. I size 9mm to .356" and use a taper crimp.

In my Ransom Rest testing I have found no accuracy advantage to oversized PC bullets and certainly not to non-sized bullets. Cramming a lopsided oversize bullet into a chamber is not going to do anything to enhance accuracy. Your crimp will be different of every round, this alone can cause a bullet to tumble.

Are you PC bullets cured to conform to the powder manufacture's specifications or are you using one of the YouTube methods?

To begin with getting an accurate load for a Glock is no short order, especially meeting the power requirement. I used to shoot in the IDPA and mainly shot a G-34. I spent many days testing loads to finally settle on one. There is a balance between bullet weight, spin rate, and speed so was the accuracy and stability of your load confirmed to begin with?

Is you barrel really clean? When you run a white patch does it come out just like it went in. The worst leaded barrels I ever encountered were out of Glock's; however properly coated and cured bullets should leave a clean barrel. I would not think the alloy would be the problem with a proper PC.

[Willbird]

Couple things to consider here.
I had to open up multiple Lee sizing dies before I got size I wanted and your die probably sizes to .355 which is really small for cast lead. I size my 9s to .3575 and many go even larger but that would depend on your gun.
Use larger expanders to make sure you dont swage your bullets while seating.
Your new batch of lead might be softer then your previous one which would swage those even more when seating. Try water quenching to gain few BHN. I also wait at least a week after casting before I load my bullets to make sure they gain full BHN before I use them.

Another thing worthy of mention is proper fluxing. I must admit that I have been guilty of getting on the lazy side with fluxing. Reading an article about heat treating bullets (I will try to link it) the author mentioned improper fluxing lowering the antimony content of his mix. In the last I have laid a small amount of beeswax into the top of the pot and stirred, I ended up with a bunch of "stuff" on top that I skimmed off and tossed in a coffee can.

last pot load I did I put about 4 times more beaswax in there, and stirred and stirred, and almost all of that "stuff" went into solution in the alloy. The only dross I had was some black charcoal looking stuff, about 10% of what I would usually skim off 20 lbs.

The author also mentioned that lowered Antimony content causing the final hardness to come a few days later.

http://lasc.us/HeatTreat.htm

Conventional wisdom has it that the industry has been reducing the antimony content of wheel weights and my own experiments in heat treating seem to confirm this. The result hasn't "yet" been softer heat treated bullets but rather bullets that took considerably longer to age harden after heat treating. The article by "Key To Metals" confirms this by stating "The alloy containing 2% Sb clearly does not respond sufficiently" in referring to age strengthening/time curve after heat treating and quenching. Recent batches of heat treated bullets took from 7 to 14 days to reach 18 BHN which is up from 2-3 days of previous batches. According to the manufacturer Lawrence, magnum shot is supposed to contain 4% antimony and 11/4% - 11/2% arsenic.

*Addendum to the percentage of antimony in wheel weight alloy: I emptied the Magma 40 pound pot and re-filled it with 35 pounds of ingots from the same batch of wheel weight alloy, cast 500 bullets and re-did the heat treating at 420o. The hardening/time curve returned to the predictable 17 BHN in 48 hours. It seems that rather than a major change in wheel weight alloy I deleted some of the antimony with improper fluxing but the results were the same regardless of why the antimony percentage was low, greatly increased time for hardening to occur. I couldn't have planned a better test, the reduced antimony was an error on my part but helped to prove the hardening/time curve of reduced antimony. Yes, that lumpy stuff floating on top of the melt when you first heat up the pot is antimony, do not remove it, flux it back in.

[hunter74]

I shoot 358 in my Glock with no leading with naked or Hi-Tek boolits. With boolits tumbling, I'm almost certain of too small dia.

Sent fra min SM-G930F via Tapatalk

[Kenstone]

If you're using a lee powder through expander you can swap out the expander with one for a 38 S&W. That fixed my swaging problem.

What he/she said:
https://leeprecision.com/pm-expan-plg-38-s-w.html

[Proudprado]

Thank you, Dragonheart, much to do.

[Proudprado]

I have ordered the expander die.

[fredj338]

The only three things that cause a bullet to tumble in my exp is a bullet too small, bullet base damaged or muzzle crown damaged. So check the bbl muzzle for any nick or burr. Then maybe a bit more flare on the case mouth or a 'M' style expander. I size all my 9mm to 0.357" for all my 9mm including stock Glock.

[Willbird]

The only three things that cause a bullet to tumble in my exp is a bullet too small, bullet base damaged or muzzle crown damaged. So check the bbl muzzle for any nick or burr. Then maybe a bit more flare on the case mouth or a 'M' style expander. I size all my 9mm to 0.357" for all my 9mm including stock Glock.

In more than 1 caliber both rifle and pistol bore leading led to tumbling bullets for me.

Bill

[popper]

tumble in my exp is a bullet too small Which means it doesn't take to the rifling correctly. Most 9mm brass is hard and has a tapered wall so base may get sized down and front band is normal. Expander plug must expand the case at the boolit base, not just the neck. Some aren't long enough for heavy boolits.

[Willbird]

There are quite a few folks seeing keyholing with 147 grain plated bullets too. Case taper sizing down the bullets could be involved there. Many 9x19 are 1:10 twist while 38 and 357 have traditionally been much slower and work well with much longer bullets

[fredj338]

In more than 1 caliber both rifle and pistol bore leading led to tumbling bullets for me.

Bill

Ok 4 things. I have never had bore leading like that. Which is not unlike bullets too small, they do not take rifling well if the bore is full of lead.

[fredj338]

There are quite a few folks seeing keyholing with 147 grain plated bullets too. Case taper sizing down the bullets could be involved there. Many 9x19 are 1:10 twist while 38 and 357 have traditionally been much slower and work well with much longer bullets

I think when that happens you'll find guys loading plated @ 0.355" dia, failure for most. Plated are lead bullets with thin copper, they want to be sized like lead bullets for best accuracy.

[Proudprado]

So I took some of your suggestions and started by cleaning the barrel properly. That had an immediate positive effect, with no tumbling to about 28 or 30 yards.

Then I sorted the brass and picked one (Sellier and Bellot) for competition. I only chose that one because that's the one I have most of, but the results are dramatic. Variance in fps dropped to less than 20 feet and I was the third-most accurate shooter at this weekend's Tier 2 IDPA match in Johannesburg. This out of almost 100 shooters. I was only beaten by the carry-optics guys; the top shooter overall is also shooting PC.

Things are looking up.

[Willbird]

So I took some of your suggestions and started by cleaning the barrel properly. That had an immediate positive effect, with no tumbling to about 28 or 30 yards.

Then I sorted the brass and picked one (Sellier and Bellot) for competition. I only chose that one because that's the one I have most of, but the results are dramatic. Variance in fps dropped to less than 20 feet and I was the third-most accurate shooter at this weekend's Tier 2 IDPA match in Johannesburg. This out of almost 100 shooters. I was only beaten by the carry-optics guys; the top shooter overall is also shooting PC.

Things are looking up.

How many rounds do you fire in a match ??

Bill

[Proudprado]

This one was 170.