What are JSP rounds used for?

[Sturmpanzer]

Well...is it primarily a hunting round or does it have any advantages over a top end JHP in the CCW world...

[44 AMP]

Well...is it primarily a hunting round or...

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.

[gnystrom]

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.

[Bob Wright]

wild cat mccane said:

Though lead is soft, without that hollow cavity shape, they don't deform. Even at 357 revolver levels.

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

[Super Sneaky Steve]

If anyone thinks a JSP doesn't expand take another look at my pictures.

Expansion of cast bullets depends on the alloy, speed and meplat.