I think it's supposed to improve it brybenn, but as soon as I got mine..I ran samples of every ammo type I had through it (which is allot), then tested modified..and unmodified ammo. Even if what I had was a hollow point to start with (ie, Winchester white box garbage) I STILL ran it through. This was a few years back, but if memory serves...it either didn't change accuracy at all, or improved it slightly. Only dramatic change was the terminal results.
I subsequently did a quick test on the gophers themselves when I got out west with these Blazers. The solids hit with a "thup" sound, passed through..and resulted in crawlers. (body shots) The Waltzed ones hit with a louder "THAPP" sound, inside parts exited at the very least...sometimes flew away...and immediate demise 9/10 times. The 1/10 didn't get more than a foot away from where they were hit. Nobody needs to believe me...but I shot over 4,000 rounds of this stuff on a week long trip..and have lots of gooey photos to back this up. If you lived close, I'd be happy to run some ammo through it for you to test.