The Making of the Centaure Thuer Conversion

# Quest for a Modern Thuer Conversion

# The making of the Centaure Thuer

# Loading Thuer Cases

# Shooting the Centaure Thuer

# Learning by Doing

# Conclusions


Quest for a Modern Thuer Conversion

Why would one want to have a perfectly functional Centaure “1960 NEW MODEL ARMY” converted to shoot cartridges? What does such a conversion have that a quality Single Action Army or conversion clone of the replica industry does not offer at a quarter to a third of the price out of the box?

But do we conversion-aficionados want to start another argument about history, passion and desire?

You probably heard about this vicious bug Bacillus Conversicus (BC). Many good pards & pardettes got bitten. Once you have contracted BC you can count on regular acute attacks. I got infected early 2002 when I acquired my first Uberti Colt Richards-Mason Army conversion in .44 Colt and I have not recovered since. Actually I like these attacks. The only therapy with a clinically proven effect today is targeting, tracking down and liberating another conversion pistol. The intermittent application of drop-in cylinders, with & without loading gates has been tried by a number of cowboys and cowgirls with temporary success, too. However, no permanent cure is known!

Original Colt 1860 Army Thuer conversion

For a couple of years I have been drooling over these Thuers. I wanted a quality repro of a Colt Army Thuer conversion just because and then some:

# this innovative approach on the drawing board from the late 1860s to get rid of surplus stocks of Colt C&B pistol parts from the Civil War and to avoid paying licensing fees to Smith & Wesson and Rollin White is just plain stupid elegant.

# I wanted a modern made and “new” looking pistol that I can shoot without guilt-feelings. This ruled out the real thing.

# Despite her reputation of functional flaws on the range I enjoy the quality craftsmanship of this never popular pistol.

# When Uberti sold a few prototype Thuer Armies and Thuer conversion kits a couple of years back I made up my mind too late and missed the opportunity.

# Another chance to own a Thuer replica seemed to unfold during Fall 2007 when my friends from HEGE in Messkirch/Germany presented a series of pictures of their prototype of a Thuer Army made from Uberti parts ( by a German gunsmith. It appears this project has been stalled or is many moons away from commercialization.

HEGE Colt 1860 Thuer Army made of Uberti parts, with accessories & loading tool, courtesy HEGE, Messkirch


The Making of the Centaure Thuer

During my search for a conversion artist to make my Centaure Richards I became aware that Nedbal had been making Thuer Armies from old Ubertis since 1997. Actually he is doing them quite regularly on special order - including loading tool and all.

Nedbal Uberti Colt 1860 Thuer: C&B cylinder installed, loading tool, conversion cylinder & ring and 2 Thuer cartridges

Here is more good news regarding newly made Thuers: While one Internationally respected & experienced Italian replica factory took a decision against tooling for a full scale Thuer conversion production a couple of years ago there are now a few gifted conversion gunsmiths out there on both sides of the Atlantic that are happy to make our dream come true of a period correct & shootable Thuer custom conversion.

Therefore, when this pre-owned Centaure Regular New Model Army (RNMA) #7266 from late 1967/early 1968 came my way from a pard in the next village who had used her during the past 40 years (!) in bulls eye competition I grabbed and liberated her as the base gun for this Centaure Thuer conversion.

RNMA #7266 1st variation 3rd sub-variation after purchase – base gun for the Centaure Thuer conversion

In March 2008 I asked Nedbal if he would do a Centaure Thuer for me using this pistol and he agreed. So when I collected the Centaure Richards I left him this baby for the Thuer project. Incidentally, Nedbal happened to have one of his Uberti Thuers in the shop ready for final fitting and assembly. But the specs of her conversion ring were a mite off and did not work with my pistol.

Centaure Thuer Conversion

Project Outline

Base pistols

RNMA 1st variation, 3rd sub-variation #7266

Barrel marking



.44 Thuer/.44 C&B

Rifling groove diameter




Conversion ring

spring loaded type

Conversion cylinder

modified extra C&B cylinder #969 with Centaure proprietary naval scene

C&B cylinder

Centaure custom engraved with proprietary naval scene


modified C&B hammer from Centaure


Centaure (steel, not cut for stock)


Centaure (brass)


blued and case colors


loading tool, Thuer cases made from .44 Magnum brass

As with the Richards project Karl Nedbal picture-documented the progress of the project. Here we go:

#1 Milling of the Thuer Conversion Ring

Rough contour (left), more precision milling needed (center); almost completed (right)

#2 Conversion Cylinder

Rear section with nipples of Centaure percussion cylinder removed to meet Thuer specs (left), Thuer conversion ring and cylinder installed right)

#3 Loading Tools

Newly made loading tool disassembled for the Centaure Thuer Conversion (left), that’s all you need to load your Thuer cartridges (right)

This Thuer conversion project developed its own dynamics: exactly 3 months after I collected the Centaure Richards Karl Nedbal presented the Thuer to me. August 22, 2008 was the day of truth when I took possession of my new toy.

Master Nedbal and 3 Thuer Army conversions (left), which one is the Centaure, the Uberti or the original Colt (right)?

Although Centaure #7266 saw many years of black powder shooting I asked Nedbal not to do a full restoration of the pistol, particularly not to “push” the worn wedge. But I could not stop him to nicely doming and fire-bluing all screws like you would expect on a NIB original Colt Army Thuer conversion that just left the Hartford factory during the late 1860s. See for yourself.

Nedbal’s Centaure Thuer Conversion #7266 cased with Dixon flask, FAUL nipple wrench, reloading combination tool & extra percussion cylinder

Nedbal’s Centaure Thuer Conversion #7266: loading slot of barrel opened up for easy front stuffing of the Thuer cartridges

Nedbal Centaure Thuer #7266: close-ups of the conversion cylinder installed, with loading tool and empty cases

For easy loading and ejection of the empties the master re-contoured both sides of the barrel and opened the loading slot like on an original. He also drilled and threaded the percussion rammer-plunger to receive the Thuer priming punch.

Breech side view of Centaure barrels: percussion left and Thuer right, note re-contoured loading area (left), Thuer ring installed (right)

Centaure cylinders: percussion left and Thuer right – breech view (left), front view, note bored-through chambers of conversion cylinder (right)

Centaure Thuer conversion ring and cylinder separated (left), breech view of conversion ring (right)

Three big questions need to be answered: will the reloading combination tool work for me as Karl Nedbal demonstrated in his shop? Will I hit what I am aiming at with my Thuer reloads? And finally will the ejection mode of the conversion ring do its job?


Loading Thuer Cases

The pictures below were taken during my first reloading session with the Thuer cartridge loading fixtures as the loading tool was called back then. I use large pistol primers for the cases Nedbal machined from .44 magnum cases. The bullets are soft lead & lubed hollow base conicals of 280 gr.

Priming the Thuer case (left), primed case sitting on loading tool (center), seating the bullet 1 (right)

Nedbal gave me a handful of these 280 grainers together with the loading tool. The cases were filled “to the rim” with the holy black (Czech Jagdschwarzpulver V, similar to FFg), although the Vienna Proof house approved the Centaure Thuer for smokeless!

Seating the bullet 2 (left); my first Thuer cartridge loaded with the 280 grain conical (right)

Once I found my routine of turning the tool forward and backward around the arbor of the Centaure loading these cartridges is a simple, straight forward operation. I have an idea now how the oldtimers felt sitting on the porch of the bunk house reloading Thuer empties yesteryear.


Shooting the Centaure Thuer

First time out on the indoor range in Hofheim with the Centaure Thuer, August 27, 2008. Loading the 6 cartridges is easy. Only very little force is needed to push them into the front of the chambers. The first round fired downrange from 25 meters provides a good first impression. Nice boom, pretty thick smoke, easy manageable recoil of the 280 grainers.

Loading the Thuer cartridges from the front using the loading lever (left), historical moment first Thuer round fired in Hofheim … ever (right)?

Next 5 rounds fired in quick succession, quick recovery from recoil. Hits produced satisfactory POA/POI at 8 meters and positive ejection of the empties with the conversion ring in ejection mode.

Recoil is easily managed (left), positive ejection of the empties during this string (right)

It is a joy to shoot this Nedbal Centaure Thuer. She functions reliable most of the time if I do my part.

It is recommended that you pay attention to the details and don’t get over-excited, however, like counting your empties is advisable if you do not wish to end up with a “Thuer Magnum” like I did.

This Centaure Thuer has her personality. This is not what I would call a “forgiving” pistol. I am very happy to have her and look forward to putting her through the paces of more serious target shooting.

“Thuer Magnum”: fresh round loaded on top of an empty (left), at 15 meters she is printing a bit high and to the left, calls for lighter bullets (right)

Gave her another work-out November 26, 2008. Same charge of a full case of black powder but this time I loaded soft lead flat base conicals of 200 gr. and .450 diameter. Since the bullets did not come lubricated I used some hand creme with high water content as lube and to keep the front of the cylinder and the barrel clean. The Centaure Thuer liked these 200 grainers much better than the heavy 280 grainers of the previous shooting session. Impact was right on target, just 2” to the left of POA and that’s OK by me. There were no issues with cylinder locking up from black powder crud or cartridges or empties moving forward during recoil.

Pair of Nedbal Centaure conversions: Thuer #7266 (top) Richards #4079 (bottom)


Learning by Doing

One issue related to the reloading process remained unsolved with these lighter bullets. Seating them straight on the powder is almost impossible with the Thuer loading tool. Therefore, for the next shooting sessions hollow based and bevel based 200 grainers of .450 diameter were loaded. By now my loading chores were shared by FROCS # 7 Bumble Bee. A few weeks back Bumble Bee decided that he just could not pass on Nedbal’s Uberti Thuer in the shop, and liberated her for his cowboy armament. With these 2 types of bullets we could improve on our loading procedures, turned out properly seated bullets > 9 (HBs) or > 8 times out of 10 (BBs).

Some observations ought to be mentioned here:

# chamber & case dimensions of these two Nedbal Thuers are the same because the master duplicated the measurements of his original Thuer Army,

# although the rifling diameter of the Bumble Bee’s Uberti Thuer is .452, i. e. bigger than my Centaure’s .447 we used the same .450 diameter hollow base and bevel base bullets in both conversions. Accuracy in terms of bullets’ spread on the target of these 2 Thuers is comparable but different POIs were noted.

# Some unpredictable forward movement of empty cases or cartridges from recoil was noted in both Thuers. This affected cocking and/or firing of the pistols. In a few instances disassembly of the pistols was necessary to correct the situation.

# A meager velocity (V2) averaging only 140 m/sec (460 fps) was chronographed with both types of these 200 grainers.

FROCS #7 Bumble Bee shooting the Centaure Thuer: nice smoke and lots of sparks with CZ Jagdschwarzpulver V but little recoil

The analysis of the velocity data led to the development of still another load with hot Swiss CH1 under soft lead 195 grainers/.450 dia of heel type design with flat base. As a control group the same BP/bullet combination was loaded in the extra percussion cylinders of the two Nedbal Centaure and Uberti Thuers, respectively. Here is what we learnt:

# No matter if the Thuer or the C&B cylinder was installed these loads made the pistols kick like a mule. In the Centaure they felt like an unpleasant .357 Magnum. Felt recoil was a little less with the Uberti.

# Little smoke, no sparks worth mentioning.

# Centaure average velocity (V2): Thuer 310 m/sec (1017 fps), C&B 297 m/sec (975 fps)

# Uberti average velocity (V2): Thuer 260 m/sec (853 fps), C&B 249 m/sec (817 fps)

Four comments: everything else being equal the

1. slightly lower velocities recorded with bullets fired from the C&B cylinders can be explained by the different type of ignition used, i. e a “closed cartridge system” in the Thuers but gas back-firing through the nipples when the C&B cylinder was installed,

2. whereas the comparatively lower velocities and less kick (!) of the Uberti are due to her larger bore diameter.

3. Although a crimp is not possible with Thuer cases heel type bullets with flat base can be seated firmer and straight into the cases compared to HB or BB type bullets.

4. In combination with the hotter CH1 this is accountable for the much higher overall velocity compared to the earlier experiments.



Having studied original and modern made Thuers some these loading and shooting sessions taught me a lot about the Thuer conversion system. They provided some insight why the military or real cowboys preferred their battle proven C&B Armies and Navies, or the more advanced contemporary Remington cartridge conversions or S&W Americans over Colt pistols of Thuer design. I feel this is an important consideration that adds to the shooting fun but also brings the real life value of these different ignition systems into historical perspective.

# Thuers have potential for reasonable accuracy but they share one inherent flaw, originals and today made ones alike. Provided the latter are turned out period correct after an original conversion cylinder. Like the originals from the 1860s the chambers of the Nedbal Centaure conversion cylinder and Nedbal Uberti Thuer conversions for that matter have their tapered profile all the way down from the mouth to the breech end!

# During firing the conical bullets have no bearing surface in the cylinder, are not guided by the chamber walls, until they hit – somewhat upset - the forcing cone and the rifling of the barrel. Because the front diameter of the chambers is greater than the rifling groove diameter of the barrel. Oversized bullets represent no solution here. In Bumble Bee’s and my experience soft lead 195 or 200 grainers, the diameter adjusted to the rifling groove diameter of heel type design are the optimum followed by hollow based ones as a second choice. Bevel based bullets can be considered but flat based ones without heel cannot be recommended.

# These tapered cartridges are loaded from the front into the Thuer cylinders. They are kept in their chambers by friction only, as are the empties after firing. They might and do move forward from recoil or even when the pistol is carried on a person walking or riding on horseback for a longer period of time. This forward movement can prevent ignition of the cartridge, it might also make re-cocking and firing a Thuer difficult to impossible when the going gets tough. This aspect could explain why big bore Thuer revolvers never caught-up to become the preferred fighting weapons of the Americans back during the days.


WDN/June 20, 2013

© 2007 Wolf D. Niederastroth