Tumbling bullets

[MR.G]

Why would some bullets tumble when fired from a gun. The gun is a .357 with a 2-1/2" barrel. Some brands of .38 special tumble and keyhole in a paper target, even at twenty feet or less.

 

[Blast]

I'm just making an educated guess, but possibly the bore twist might be different because the .357 is far more powerful than .38 special requiring less twist per inch. After all, the .357 pistol is designed for the .357 cartridge.

 

[Blue Duck357]

Pretty much with Blast on this.

Often the faster you drive a bullet the less quick a twist you need to stabilize it. Another problem can be too soft of a lead bullet not being properly gripped by the rifling. Can't know for sure but I'd almost bet your looking at both problems, too of soft lead being driven too slow for your gun.

 

[7th Fleet]

Two things to check to stop the keyholing. Make sure that your revolver barrel's grooves aren't plugged up with lead. Also try a different weight and construction of bullet and see if this helps.

7th

 

[C.R.Sam]

As above....and.
Check the exit end of your chambers. If they are smaller than the bore they can induce erratic bullet performance. Quick and dirty check is to open cylinder and see if a jacketed .357 bullet will go in from the front all the way to the case mouth.

I don't buy the twist difference as likely. For years have done some quality match work with soft loads in .38special cases out of .357mag guns.

Sam

 

[Al Thompson]

That's a pretty strange problem. What sort of revolver is it and what are the .38 loads that your having problems with?

I've seen handguns that tumbled bullets, but it was an all or nothing sort of thing.

 

[jar]

The first question I have is which tumble and which don't?

Can you give us a listing of the brands and loadings?

Are these factory or reloads?

Is this consistent or just Some of them?

Mark the cylinders and see if it's one or more cylinders consistently?

 

[MR.G]

Gun is a S&W 686. Ammo was S&B 158GR. jacketed round nose

 

[Al Thompson]

Thought about this a bit. If it's tumbling with one sort of ammo but not other brands/weights, it an ammo problem.

I'll bet that those S&Bs are undersized.

Change loads and see what happens.

 

[braindead0]

I agree with Gizmo99, change loads. I routinely fire 158gr LRN/LSWC at 700-850fps from my 2" .357 with no problem.

 

[alp-257]

MR. G:

I had the same problem with three boxes of S&B ammo (.38 Spl - 158 grains - RN) in my S&W 66 2,5 inches.

The ammo was old and really "soft"!. After +/- 30 shots the revolver barrel's grooves were plugged up with lead !.

Best Regards - ALP

 

[mec]

Havn't seen this with 158 grain bullets but 200 grain lead going 600 fps or so is marginally stable in the 2" .38 special barrels. It usually gets to the target point on-and then turns sideways. Same thing with some of the heavy,slow moving .455 loads.