.38Spl Jacket-Core separation !?!?


September 30, 2010, 08:54 AM
One of my shooting buddies asked my opinion about "something weird" happening to his new batch of .38 Spl reloads.

He recently bought a supply of 158 Gr JSP.357 bullets & loaded them according to his own favorite tried & proven load recipes. One of those (and one i successfully tried as well, I might add) is 3.5 Gr of HP-38.
As these were a new brand of bullet , he loaded some "test loads", ranging from 3.3 , over 3.5, 3.7 & 3.9 gr. of HP-38.

Now, I know this guy : he's been shooting & loading for almost 30 years now, and has had armorer's training in the armed service. He knows his stuff, & is certainly no reckless fool when it comes to guns & ammo.

What happens (& I witnessed this several times yesterday at the range) is that when he fires those loads form his 6" barreled S&W 686 at the bullseye target at 25 meters, you can actually SEE the bullet hitting the FLOOR of the range ONE FULL SECOND AFTER the shot has been fired.

Not only that, but (OMG !) this is only the lead bullet core kicking up dust out there, as THE JACKETS STAY STUCK IN THE BARREL !

Now I seem to remember that -way back when- (yes, I'm that old) the SPEER reloading manual warned against light loads with one particular bullet design : a 140 or 145 Gr semi-jacketed .357 bullet, as these could show just this kind of core separation (those bullets are no longer made, I think) .

What's really weird IMO, though, is that those same bullets, loaded in front of 4.7 to 5.0 gr of HP -38 in .357 Mag cases, work perfectly !
Can pressure generated by this load (5.0 gr in .357Mag case) be that much more than that from 3.5 Gr in .38 Spl cases, ?

Anyone have any experience with this phenomenon (as to possible cause &/or cure) ?

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September 30, 2010, 09:08 AM
More like a low pressure problem. That load is at or below the minimum, and the pressure is at the threshold of pushing the entire bullet out of that longish barrel. So the jacket sticks and the momentum of the core takes that core out .

September 30, 2010, 09:39 AM
This phenomenon is covered in the Speer #13 and #14 (and 11 IIRC) . Speer stopping showing many of the reduced loads in .38 Spl because of it. They show a max with no minimum. It is rare, but it happens.

Jim Watson
September 30, 2010, 10:26 AM
A coworker did not want to lead his bore with nasty old wadcutters and so made up some light loads with JSP bullets. He stuck a jacket and did not notice it because the core actually hit the 7 yard target. The next shot bulged the barrel.

The starting load in the book is not always a minumum load, but sometimes it is.

September 30, 2010, 10:47 AM
Because you asked:

Yes, and probably the same bullet you are using now.
The difference being a full house hunting load, on a bitter cold day.

What saved ME was the half jacket was stuck in the forcing cone and squeeked when I cocked the hammer for the next shot!
I let the hammer down and swung out the cylinder to see what was up:what:.
I have never shot another half-jacket bullet since and used those 1000 bullets for weight ballists in the bottom of my safe.

I spent zero time trying to annalize or "improve" that load and don't care to know the why, just consider myself lucky to still have 2 hands.

Now, a question for you, chriske;
Why did you (he) keep shooting after the 1st shot that went bad?

September 30, 2010, 12:09 PM
Speer for one no longer even lists 158 grain jacketed bullets for use in .38 Spl or .38 Spl +P.

Hodgdon does list it, but the minimum starting load with HP-38 is 3.8 grains - 4.3 MAX.

If your friend wants to load mouse-fart loads in .38 Spl, he better do it with cast lead bullets.

They have way less bore friction due to lead being "slicker" and also bullet lube to grease the way, and won't stick in the barrel.


September 30, 2010, 12:44 PM
As noted, it's a simple case of using the wrong bullet for the job. In this case, the job was producing a light load for the .38 Special, and the wrong bullet was a jacketed one.

I load approximately 10,000+ light .38 loads per year for our SASS shooting, and wouldn't even consider using a jacketed bullet, even if they were allowed. Use the proper tool for the job and all will be well.

Hope this helps.


October 5, 2010, 05:52 AM
Indeed, when I wrote I successfully used 3.5 Gr of HP-38 I did fail to mention it was behind 158 Gr RN cast lead bullets.

Tilos : there were loads of 3.3, 3.5, 3.7 and 3.9 gr of HP-38 to be tried, so we fired a couple of each single-shot-wise :
Load one cartridge in cylinder, fire, swing open, check barrel, push out stuck jacket with cleaning rod, load again...

Thanks for the replies !

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