I've had several of the tools over the years, from the early model to the current model and have been quite impressed with the performance changes.
Acu-rzr tool. review.
By 'bumping' the bullet diameter up, you generally increase the accuracy in a given load or at least stabilize the accuracy. Many .22 brands and makes have slightly varying diameters and reducing the variation helps accuracy immensely.
Some barrels show little improvement, these are generally either already the same size as the bullets in use or are somewhat larger than the tool can bump up to without increasing the diameter of the tool interior.
The difference can be quite dramatic depending on the intended target.
On sodpoodles (prairie dogs), they can be quite phenomenal, the difference in impact is readily apparent as they are almost slammed backwards when hit.
Granted manually operated weapons are the most reliable, depending on how much you modify the bullet nose.
Nothing I've hit with the nasti-nose has needed a second shot, including a couple of 'yote's shot while out and about.
The Hanned line make a tool some years back called the SGB tool, it made a neat little flatpoint on the nose of standard roundnose ammo increasing effectiveness again quite astoundingly. The meplat increases impact energy by imparting the energy over a wider area.
I was so impressed with this little tool and how well it works that I went and made my own version, unlike Hanned's single 'shot' unit, my brick will do a 50 round box at once.
The CCI SGB (small game bullet) is the same thing and has been very effective in the field and this had been written about before in the gun rags.
Sadly the Hanned company has changed hands and no longer makes the SGB tools.
However Paco has come out with his
own version and it's actually better and easier to use than the earlier model.
Not inexpensive but for a hunter it's well worth the time and effort for the rounds used in the field.
As for the time needed to modify them, what's time to a hog?
For general blasting you're not going to use this stuff.
How many rounds do you use while out squirrel/rabbit shooting?
For my use a 50 rounds box lasts quite a while with careful shooting.
I've gone so far as to use the SGB'd and Nastinose .22 bullets when disposing of injured animals in town, the reduced penetration is very helpful to reduce the possibility of over-penetration and the increase in effectiveness is helpful as the animal suffers less.