What are JSP rounds used for?

"...without that hollow cavity shape, they don't deform..." That's 100% not true. JSP's expand when an HP does not due to a lack of velocity. HP's require velocity to reliably expand. A JSP will expand even if the velocity is lower.
"...wouldn't over expansion ruin a lot of good meat?..." Nope. The soft point rifle bullet is essentially the 'standard' hunting bullet. All the manufacturers make at least one. PSP, Power Point and Soft Point, for example, are all the same thing by Winchester and Remington. However, it's not a good idea to compare rifle and pistol bullet performance. Different things.
"...useless because FMJ 40 does anything an FMJ 10mm..." Irrelevant since any FMJ will make a hole of its own diameter and not much else. There's no comparing any FMJ to any JSP either.
 
I load 240 gr. Hornady XTP for my pistol in .44 mag. In the box with the bullets is a note stating that the bullets expand reliably within a specific velocity range. They worked great on deer.

When shooting at 1 gal. jugs filled with water using those same bullets in the .444 Marlin at a velocity well above the specified range the expansion was, well, explosive... I'd say not the right bullet for deer in the .444.
 
As far as use in flesh type medium, JSP are typically thought of as an intermediary between JSP and HP. Though the comment above about certain HP bullets needing sufficient velocity to expand reliably probably has a lot of truth to it. We load both JSP and HP in our .38 Special. Both are sub-MOA capable (in a rifle) and great for competition.
 
Don't think the subject has been broached here, but in some areas/states, full metal jacketed (FMJ) bullets aren't legal for hunting, or may be restricted in their use to varmints and/or fur bearing critters.

Bob Wright
 
Well...is it primarily a hunting round or...
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Because of advances in JHP design, enhancing their reliability, the use of the JSP for self defense has faded significantly, outside of areas that prohibit hollow points.

There are a lot of designs, and the devil is in the details. Some JSP designs with expand better than some JHP designs, and vice versa.

For the bulk of the 20th century, US made pistol ammo came in two flavors, lead bullets in revolver rounds, FMJ bullets in auto pistol rounds. The only different options were handloads.

That began changing in the late 60s and Super Vel showed the way. HOWEVER, many older stock semi auto designs didn't feel JHP well, but often would feed JSP rounds, and so JSPs were pretty popular for defense, until newer pistol designs (built to feed hollowpoints) and getting the "bugs" out of JHP design took over.

Today, the JSP is more often used in hunting, where its (usually) greater penetration and slightly less expansion over a JHP can be a benefit.
 
All the theories persist but if I enter the woods where bear are roaming, I guarantee you my gun will be loaded with Buffalo Bore or Underwood Extreme Penetrators. There is far too much evidence to suggest that is not a prudent decision.
 
wild cat mccane said:

Though lead is soft, without that hollow cavity shape, they don't deform. Even at 357 revolver levels.
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I would differ with you there. I've recovered factory 250 gr. .45 Colt bullets that mushroomed very well. Not the tremendous expansion of JHP bullets, but mushroomed very well.

Bob Wright
 
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