Frequently Asked Questions
What new guns are available for the Garin SureStrike System?
Cooper Firearms of Montana offers the full line of SureStrike cartridges in their smallest centerfire action called the Model 38. This action can be specified in a number of their excellent, elegant rifles. Currently the model 38 action is available in the following models: Classic, Custom Classic, Western Classic, Varminter, Varmint Extreme, Montana Varminter, Varminter Laminate, and Phoenix.
Bullberry Barrel Works, Ltd. of Hurricane, UT is a producer of custom barrels for Thompson/Center rifles and pistols. They can supply SureStrike barrels in many lengths and styles in both alloy and stainless steel.
A number gunsmiths will build fully custom rifles to your specific needs. Notable among these is Dan Coffin of Coffin Gunsmithing in Victor, MT.
Has a switch-barrel rifle been built for the Garin SureStrike System?
Yes, Dan Coffin in Victor, MT has produced a great looking rifle called the Garin SureSwitch Rifle, based on the CZ 527 receiver. To produce this rifle, the action is first placed in a special fixture. The face of the action is then milled normal (perpendicular) to the centerline of the bore. The barrel now seats against the face of the action rather than internally. In the case of converting existing barrels, (.22 Hornet for example), the chamber end of the barrel is machined off to compensate for the metal removed during this truing. Also, in the case of .22 Garin vs. the .22 Hornet, the chamber must be further shortened because the Hornet is a slightly longer case and simply rechambering would produce an abnormally long freebore/throat. This process produces a chamber that still fully supports the cartridge base. If a .22 Hornet bolt is used, it should not need modification. The barrel is now screwed in firmly hand tight (I always use some anti-seize compound, particularly on stainless steel barrels). A small alignment mark is now made on the receiver and barrel to show when they are properly aligned. A small hole is drilled and tapped through the wall of the action, and a small, shallow hole into the barrel threads. A thumb type set screw (a grub screw for any Brits or Aussies in the crowd) keeps the barrel from loosening or over-tightening when fired. Of course, if the rifle is produced from a new action and barrel, some of this machine work is eliminated.
Can I re-chamber an existing gun?
Yes, we have had a number of guns modified to our cartridges - CZ, Ruger, Savage, Stolle Panda, Thompson/Center, Young Railgun, etc. All have worked quite successfully.
If you presently own a rifle in .22 Hornet or one of its variants, re-chambering to .22 Garin is normally a straight-forward proposition. Weapons produced for the .22 Hornet do not normally require any modification to the bolt face. The rim of the M1 Carbine case is .010” larger in diameter than the Hornet. Therefore, some extractors may be slightly long and may require minor modification with a stone. Magazines may need modification, or in some cases, be exchanged. In the case of the CZ 527, for example, the Hornet magazine can be modified, but their .221 Fireball magazine only needs the feed lips tightened slightly and otherwise will work as is. Another option is to use one of Jim Calhoon’s single shot adapters in place of the magazine. If you want to re-chamber an existing Hornet barrel, it must be set back a couple of threads. If you don't do this, you will end up with an abnormally long throat causing a long bullet jump - not the greatest thing for accuracy. This is a pretty common procedure, and should not cost much.
The Cooper Model 38 in .22 Hornet is a most excellent choice for conversion to a .22 Garin. The reamer will clean up the chamber quite nicely. You should, however, have the barrel set back a few threads because the Hornet case is a bit longer than the carbine case.
Savage, Ruger models #1 and #3, and Browning single shots are also fine choices for conversion.
Can I reuse my Calhoon 19 Badger brass? — some brass forming theory
Yes, your Calhoon brass can be reworked to .17 or .20 Garin. But before looking at the details, let’s define some basic principles. When the diameter of the neck of a brass case is reduced, the excess brass from the process must go somewhere. The typical result is a thickening of the neck. There are two ways to accommodate this extra thickness. You can simply accept it and design the weapon’s chamber to a diameter large enough to chamber the modified round. To determine the nominal diameter of the neck of a rifle’s chamber, we must add up the diameter of the bullet, plus twice the thickness of the neck brass (the brass runs all around the bullet), and twice the clearance we want between the outside of cartridge’s neck and the chamber’s neck wall. This is where a bit of design philosophy enters the picture.
Factory brass, even the best, isn’t perfectly symmetrical. Therefore, the thickness of the neck is not completely uniform. Non-uniformity creates two problems. First, if the neck thickness varies, the inside and outside of the neck cannot be concentric, so the bullet held by the neck will not be concentric with the centerline of the chamber or bore of the barrel. Secondly, if the thickness of the neck is not uniform, it will expand at an uneven rate as the powder burns and the pressure rises. This means that the neck tension (the grip of the neck on the bullet) will not be released uniformly. Both of these conditions are aggravated by the sizing operation. Although these effects are relatively small, they are significant in longer range, high accuracy shooting. The preferred method of dealing with these neck thickness and concentricity issues is to turn the necks to a uniform dimension. To achieve the best results, the outside surface should be turned. This process shaves the brass off the outside of the neck while the case is rotated on a mandrel. It is harder to describe this operation than to perform it.
Calhoon brass is produced by simply sizing .30 carbine brass to .19 caliber. This process thickens the neck considerably - up from approximately .012” - .014" to .017” thick. This in itself is acceptable since the chamber’s neck is sized appropriately. All the Garin cartridges, .17 thru .25 caliber, are designed around a .010" thick neck which does require neck turning. A .19 caliber Calhoon cartridge opened up to .20 Garin without reducing the neck thickness would most likely not chamber, or if it did, might produce abnormally high pressures due to high neck tension. In other words the diameter of the bullet plus 2x the thickness of the neck brass is greater than the diameter of the chamber neck. But don’t despair, neck turning is pretty straight forward, gives you much better control of neck tension, and we can provide all necessary tooling.
The chart below shows the calculations used for the above conclusions.