Tumbling Bullets

[henryinpanama]

I'm loading 9mm with 5.0 grains of CFE Pistol and a Lee TL356-2R. Velocity is right at 1000 fps. I've never had a misfire or FTF with this load, but the bullets are tumbling. I've noticed that my Taurus G3C has very shallow rifling. I suspect that the lead bullets are traveling too fast to get a grip on the shallow rifling. Appreciate any input.

[JonB_in_Glencoe]

Calculate chamber pressure, then confirm your alloy is hard enough.

[FLINTNFIRE]

I had tumblers with that same bullet even powder coated , I prefer MP or NOE hollow point molds as they do not tumble . I put it down to undersize and it was not every one that tumbled just a few , undersize cavity or what I was not sure and with other molds to use , I made life simple .

[fredj338]

Not likely to fast. A tumbling bullet is almost always too small. So try a larger bullet. Pull a loaded round & measure the post crimped bullet. Many times too mcuh crimp is applied or the expander is too small & you get bullets sized in the case.

[wv109323]

The actual bore size of 9mm barrels are all over the map, from .354 to .359. Also there are multiple twist rates for the 9mm, from 1:10 to 1:32. Plus as the previous post you may be sizing down the boolits when you are seating.
Most manufacturers of reloading dies, manufacture the size of the neck stem with jacketed boolits in mind. The neck sizer portion of the belling die may be as small as .352. Plus the deeper you seat the bullet into the case the more likely that you will be downsizing the boolit, as the 9mm is a tapered case.
Plus your lead alloy plays a part in gripping the rifling.
I can not diagnose your problem from afar. I would load some rounds at around 750 FPS and see if they tumble. Next I would seat a few bullets as you are now doing. I would pull them to see if they are being downsized during seating or crimping. Also you need to know your actual bore size and you can do this by slugging the bore.
The 9mm in my opinion is one of the most difficult rounds to load cast boolits and get excellent results. I know I am trying to get a CZ pistol to shoot accurately myself.

[popper]

Depending on seating depth, it's a moderate to near max load, 1100 fps min. I suspect both, too small/soft. I had the same problem in 40sw with a near pure alloy, ~950 fps. Accuracy was fine but some hit sideways. Long loose strips of alloy in the grooves, presumably removed by the next shot. Soft is automatically smaller as there is no spring back of the alloy from sizing. The 9mm case is tough and WILL size bullets down. Get a proper expander.

[henryinpanama]

Thanks, guys. I appreciate the help.

[gwpercle]

Thanks, guys. I appreciate the help.

It might be the Tumble Lube design itself ... all the tiny TL grooves not giving the rifling enough to get a good grip . I'm beginning to think a couple decent sized driving bands make for a better boolit . I have both the conventional lube groove designs 356-125-2R and 356-120-TC , when sized to .357" neither one has shown any tumbling in 4 different 9mm pistols .
Can you try a non tumble lube grooved boolit and size it to .357" ... you can still tumble lubricate a conventional design ... that might solve your problem .
I and my test 9mm's have shown a preference for standard lube groove design , 120 to 124 grain weight and truncated cone nose shape .
Gary

[henryinpanama]

Yesterday I loaded a dozen rounds with 4.1 gr CFE and the 124 gr lead bullet. I first belled the case mouths a bit more, adjusted the seating depth a bit shallower, and lightened up on the crimp. I went to the range this AM and all rounds functioned properly and no bullets tumbled. Thanks to everyone for the help.