Paco Kelly’s Improved ACU-RZR and NASTINOSE Rimfire Bullet Tool


by Jeff Quinn

photography by Jeff Quinn

June 17th, 2008

UPDATED August 28th, 2008




UPDATE August 30, 2011

Please Note that Paco has a new web site for his tools:


June 17th, 2008

Paco Kelly has now introduced two new versions of his ACU-RZR tool at the request of shooters who want faster production. He now has models which will reshape and resize the bullets in either three or four cartridges at a time, depending upon the model chosen. This makes for much faster production. With either tool, you still get two different sizing options, depending upon which end of the tool is used. The chambers can be sized to the customer’s specifications, but must be the same on each end. The Maxi-3 does three at a time, and the Maxi-4 does four at a time. At the time of this writing, the Maxi-3 is $102 US shipped, and the Maxi-4 is $128 US shipped. These prices include shipping to anywhere in the US only. The older Phase 1 and Phase 2 tools are no longer built, but the Phase 3 and Phase 4 are still in production at $71 US and $78, respectively, including shipping to anywhere in the United States. These new Maxi 3 and 4 tools are a good idea, and greatly speed production. Simply seat the cartridges into the tool, select the proper rod which suits your application, and form the bullets with a few light taps of a hammer, just like with the older style tools, but doing more than one cartridge at a time. As always, these tools are built with precision craftsmanship, and made in the USA.

Paco's latest tools: the Maxi-4 (left) and Maxi-3 (right).









With Paco's new Maxi-3 and Maxi-4 tools, you can re-form and accurize up to four cartridges at a time.

It has been over two years since I reviewed the dandy little ACU-RZR and NASTINOSE bullet reforming tools as produced by Paco Kelly. Those who read regularly are already familiar with Paco Kelly’s writings, as he has written articles for Gunblast as well as for his own website,, and has authored a couple of very good books.

Paco is also a Shootist, gunsmith, inventor, and tinkerer. One of his most useful devices is the tool which he invented several years ago to resize and reshape the bullets of .22 rimfire ammunition to make it both more effective on game and vermin, and also more accurate. Rimfire ammo is made to fit every .22 rifle and pistol that has been made since the cartridge’s inception well over one hundred and fifty years ago. With the dozens of gun makers over those many decades making chambers of varying tolerances, ammo makers have to make their .22 rimfire ammo so that it will fit into each and every one of those guns. The result is a .22 caliber bullet that is a pretty loose fit in most of those chambers. ", as it has come to be known, bumps up the .22 caliber bullet to better fit the rifle or pistol’s chamber. The latest variation of the Paco Tool has four different sized chambers, allowing the shooter to precisely fit the ammo to his firearm. The Paco Tool allows the shooter to bump up the bullet size to increasingly larger dimensions, to get a snug fit into his weapon. Paco offers the tool with either chambers varying from .001 to .004 inch over, or from .002 to .005 inch over standard .22 rimfire ammo sizes. Bumping up the size of the bullet makes for a tighter chamber fit, which makes for better accuracy. The shooter inserts a .22 cartridge into one of the four chambers, inserts the shaping rod into the other end, and lightly taps on the rod, bumping up the size of the soft lead bullet. It is simple to do, and it works.

Now comes the good part. Getting match-grade accuracy from cheap bulk ammo is a great thing, but even better is that the Paco Tool also reshapes the nose profile of the ammo into a more effective shape, greatly increasing the killing power of the little cartridge. The tool comes with three different rods. One reshapes a roundnose or hollowpoint bullet into a more effective, blunt, cup point, with or without a hollow point. Another rod makes any standard roundnose ammo into a hollowpoint, and third rod makes what Paco calls his SCORP‘N, which is a blunt, wide hollowpoint, with a post in the middle. This is similar in shape to the Hydra-Shock ammo that is sold for centerfire handguns. Any and all of these nose shapes are much more effective than standard roundnose or hollowpoint ammunition, and the shooter can choose whichever best suits the game and the particular rifle or handgun chosen.

The newest tools work just like the originals, but by having four chambers instead of two, are much more versatile to the shooter who owns more than one .22 caliber rimfire weapon. I tried the newest version of the Paco Tool while testing a Beretta Neos for accuracy. The Paco Tool was lying there on the bench, so I decided to give it a try. The tool greatly improved the accuracy of an already-accurate pistol, and bumping the bullet up .002 inch has no effect on the reliability of the auto pistol.

For a comparison of shooting standard ammo with ammo which had been “Pacoed”, I fastened a Ruger Single Six into my Ransom Master Rest to compare the accuracy, while eliminating all human error. My old Single Six has pretty tight chambers already, and is plenty accurate, so I wanted to see if the accuracy would be improved by using the Paco Tool. It was. With some loads, the change was subtle, but with others, dramatic. The Paco Tool allows a shooter to use cheap bulk ammo instead of buying the more expensive stuff, and getting match grade accuracy at a low price. With all of the cheap ammo tested, the Paco Tool improved the accuracy. With match grade ammo, accuracy was improved a little, but not as dramatically as with the bulk Federal hollowpoint and Winchester Dynapoint ammo. Also, Winchester bulk Xpert ammo showed a drastic improvement in accuracy, and all of the ammo received a more effective bullet profile in the process.

Jeff Quinn


Also available is a very handy two-chamber pocket version.



The Paco Tool gives average ammo match-grade accuracy!

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Click pictures for a larger version.


The "Paco Tool".



The Paco Tool is hand-machined from quality brass stock, and has four differently-sized chambers.



It is a quick and simple process to re-form cheap bulk .22 ammo into more effective, and more accurate, ammunition. Top to bottom: cup-point "ACU-RZR" (shown with unaltered ammo at right); hollow-point "NASTINOSE"; and "SCORP'N" (shown with unaltered ammo at right).



The Paco Tool comes with three forming points for forming the ACU-RZR,  NASTINOSE, or SCORP'N.



The tool can also be used to re-form factory hollow point ammo (right) into a more effective shape.



The Paco Tool even works with Aguila's 60-grain Super Subsonic ammo.