Great Gun Derringer (en)

(po slovensky)

The Great Gun Derringer represents the best option for a defensive weapon in Slovakia and Czechia which can be purchased and carried by those 18 and older without any weapons permit.  There are now 3 calibers offerred in various sizes and weights down to 350 grams.  All are double barrelled, single-action where the barrel to be fired is selected by a switch on the hammer.  In .45 caliber (pictured below) the projectile has as much energy as the 9mm Makarov pistol used by most of the Slovak military and police.

The Gun

This page will describe loading procedures for the .45 caliber (11.4mm) version with 4.5" (120mm) barrels.  The gun, when fully loaded, weighs 650 grams.  Everything here is applicable to the other models offerred except for the amount of gun powder.  Check the user manual that comes with your gun for the correct amount of gun powder to use.  Using too much can damage the gun and cause injury to the shooter and/or bystanders.  Any statistics on velocity, bullet energy, etc. given here are dependent on the barrel length, caliber, bullet weight and powder charge.  A derringer with shorter barrels will have slightly lower energy and velocity in the same caliber, however, the shorter barrels give an advantage in concealibility.  The 4.5" barrels are already too long for many types of concealment, though it works well with a Concealment holster.  Various finishes are available to the metal, this gun has a matte nickel finish which is one of the more durable options.  Prices for these guns are around 300€ new.

Under current Czech and Slovak law this gun is Category D, requiring no weapons permit to own or carry concealed.


The derringer is a black powder, muzzle loading gun with ignition via percussion caps.  The percussion caps and black powder are readily available at most gun stores in Slovakia with an approximate cost of 6€ for 100 percussion caps and 20€ for 1 kg of black powder.  At the recommended load of 1.2 grams (18 grains) of black powder, this kilogram will last for more than 800 shots.  Bullets are sold by Great Gun for €0,07/each.  Therefore, the cost of shooting is about €0,17 per shot.



Black gun powder is the first propellant powder used in guns.  Saltpeter (potassium nitrate), charcoal and sulfur in a ratio of 15:3:2 is finely ground together and pressed into grains to produce black powder.  When confined, it burns rapidly producing a large volume of gas which propels the bullet down the barrel.  When fired, a corrosive residue is left in the barrel neccesitating immediate cleaning after use.  For most modern guns it has been superceeded by various smokeless gunpowders, however it is still sees use in mining, pyrotechnics and military applications, as well as guns such as this and historical replicas.  Only blackpowder can be used in the derringer.  Smokeless powders have different characteristics of burning and pressure which makes them extremely dangerous if put into a percussion gun.  Blackpowder can be purchased without any special license.  The Czech Vesuvit LC is widely available here and does not present an option of grain size.  Most other black powders come in several different uniform grain sizes which affect the burn rate.  Nonetheless, Vesuvit LC pushes the bullet out the barrel well enough.

Percussion Caps

4,0mm percussion caps work with the nipples on the derringer.  Sellier & Bellot caps work perfectly fine.  The percussion cap is a copper cup with a small amount of explosive covered with paper on the inside.  When the hammer strikes the cap against the nipple the explosion sends a flame through a small channel to the barrel igniting the black powder.



Bullets should be of a diameter nominally 0,453" (11.5mm).  The bullet should be made of pure, soft lead and should be lubricated.  The traditional lubricant for black powder guns is a mixture of lard and beeswax, 50% by weight of each.  The proportions can be adjusted to arrive at a lubricant that is soft at the prevailing temperature.  Softness is increased by increasing the amount of lard and decreasing by increasing the amount of beeswax.  The lard should be without salt.  The lard and beeswax are gently heated until both are mixed and stirred together thouroghly. This lubricant should completely fill the grooves of the bullet.  The photo shows a 200 grain (13 gram) Lee R.E.A.L. bullet cast with a measured diameter of 11,6mm.  The rightmost bullet has been lubricated.  If you are having trouble finding suitable bullets, please use the contact form and we can help you out.  The lubricant is essential to preventing lead from building up inside the barrel and keeping the fouling from the burning powder soft and easy to clean.  Unfortunately, if you buy bullets, you will still have to lubricate them because they are not sold with lubricant.

Tools and Accessories

Powder Flask

A powder flask holds the black powder and contains a built in spout allowing for the proper amount to be dispensed.  The one Great Gun sells is pretty, but expensive-- at least twice as much as what other mass-made flasks cost in online stores in Czechia and Slovakia.  A powder flask or precise measuring spoon greatly speeds up loading the gun, otherwise it will be neccesary to carefully measure on a scale each for each shot.  The powder flask should be checked to see what weight of powder the spout is holding.  If too much, carefully cut down the end of the spout until it holds the right amount.


This is used to drive the bullet down the barrel.  The one Great Gun sells is reasonably priced.  Otherwise you can make your own with 10mm brass or aluminum rod and a suitable handle.  A plastic or wooden mallet to hit against the ramrod can also be helpful.

Nipple Wrench

This should be ordered from Great Gun.  It is neccesary to remove the nipples to clean the gun well.  Spare nipples are cheap and a couple should be ordered at the same time.

Cleaning Kit

A kit of brushes, cloth patch holder, etc. should be obtained from a gunstore for cleaning.  The use of original Ballistol gun oil (in white can with green and red lettering) helps to break down the black powder residue.  Robla powder solvent is not really needed if the gun is cleaned immediately after use.  Other than Ballistol, black powder guns are cleaned with regular soapy water from dishsoap.

Percusion Cap Holder

Not strictly neccesary, but helpful when at the shooting range.  It holds ten caps and dispenses them one at a time onto the nipples, simplifying reloading.

Nail Lacquer

Essential when loading the gun for self-defense.  It both holds the percussion cap securely on the nipple and seals out water vapor.  I use clear Sally Hanson polish taken from my wife.


Following is the step-by-step procedure for loading the gun.  Nail lacquer is essential if you will not be shooting the gun right away.  Blackpowder left exposed to air will slowly absorb water vapor and become difficult to ignite.  The nail lacquer all around the edge of the percussion cap and the lubricant around the bullet seal the blackpowder from water vapor.  Sealed in this way, my gun has fired after being loaded for two months and would probably have been fine for an even longer period.  The nail lacquer also keep the percussion cap from coming loose and falling off.  The nail lacquer may be left off when practicing at the shooting range.

Fill with blackpowder

Placing one finger over the end of the spout, turn over the flask and press down the button.  This fills the spout with blackpowder.  Release the button, the turn the spout back up.  Now the spout contains one measured charge of powder.  Pour it down the barrel.  Repeat for the other barrel.  Take care not to accidentally fill one barrel twice.

Load bullets

Take a lubricated bullet and set it onto the mouth of the barrel.  Start the bullet into the barrel, either using the depression in the handle of the ramrod or gentle hammering.  Once started in the barrel, push with the ramrod all the way down.  While shooting, as fouling will build up, it may be neccesary to use the hammer to force the bullet down.  Ensure the bullet pushed all the way in.  Repeat for the other barrel.  Suitable marks can me made on the ramrod, as shown, to indicate when the carrel is empty and when the bullet is pressed all the way down.


With the hammer at "half-cock", that is pulled back until the first click so it is a few mm away from the nipples, move the switch away from the nipply you will prime.  Place a percussion cap firmly on that nipple and (if you are not shooting immediately) coat the sides all around the cap with nail polish to seal it.  Move the switch and prime the other side.

Shooting and Cleaning

The gun is fired by pulling the hammer all the way back and pulling the trigger.  Pressing the switch to the left fires the top barrel, to the right the bottom barrel.  After shooting, either immediately clean with hot, soapy water or else spray the inside of the barrels with Ballistol and rub with a soft brush to spread it around then clean later that same day.  Leaving the barrel uncleaned will lead to corrosion.