The Making of the Centaure 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 clone 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?

Original cased Colt 1860 Army Thuer conversion with spare C&B cylinder

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 RM Army conversion in .44 Colt and 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!

For a couple of years I have been drooling over these Thuers and wanted a quality repro of a Colt Army Thuer conversion…just because plus…

# this innovative approach on the drawing board from the late 1860s to get rid of surplus stocks of Colt C&B

One of the few known Uberti 1860 Thuer Armies, courtesy Cimarron, Fredericksburg

pistol parts from the Civil War AND to avoid paying licensing fees to Smith & Wesson and Rollin White is just plain stupid elegant

# I want a modern made and “new” looking pistol that I can shoot. This rules out the real thing which I cannot afford, anyhow.

# 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 (left picture).

# 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. But it appears that this project has been stalled or is many moons away from commercialization.

Nedbal Uberti 1860 Thuer, conversion cylinder installed

Nedbal Uberti Thuer: conversion cylinder (top), C&B cylinder installed (bottom) & accessories

During my search for a gunsmith for the Centaure Richards I became aware that Nedbal had made Thuer Armies from old Ubertis since 1997. Actually he is doing them quite regularly on special order - including loading tool and all (above pictures).

While one Internationally respected & experienced Italian conversion replica factory took a decision against tooling for a full scale Thuer 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 both period correct & shootable Thuer custom conversion.

Therefore, when this pre-owned RNMA #7266 came my way from a pard in the next village who had used her for 40 years (!) in bulls eye competition I jumped on the

#7266 after purchase – base gun for the Thuer conversion

Opportunity, grabbed and liberated her as the base gun for this 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

Richards I left him this baby for this 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 just a mite off to work with my Centaure.

It will be a couple of months before she is completed. As with the Richards project Karl Nedbal promised to picture-document the progress of the project. Here we go:

#1 Milling of the Thuer conversion ring

Rough contour

More precision milling needed

…and almost completed

#2 Conversion cylinder

Thuer cylinder lathed to fit

Thuer ring and cylinder installed

#3 Loading tools

Accessories for the Centaure Thuer Conversion

That’s all you need to load Thuer cartridges…

This Thuer conversion project developed its own appreciably positive 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 Thuers

...which one is the Centaure or the Uberti or the original Colt?

Although #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 1st generation Colt. See for yourself.

Left side


Right side: loading area of the barrel lug has been re-contoured for easy loading of the cartridges


Closer views of Centaure Thuer #7266…

…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.

Barrels: Centaure C&B (left) and Thuer (right)

Thuer ring fixed, resting on cylinder

Cylinders breech view C&B (left) and Thuer (right)

Cylinders front view C&B (left) and Thuer (right)

Thuer ring and cylinder separated

Breech view of conversion ring

Three big questions remain: will the reloading combination tool work for me as Karl Nedbal demonstrated it 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: Here are a couple of pictures of my first experience loading Thuer shells using the cartridge loading fixtures as the loading tool was called back then. I use large pistol primers for the cases machined by Nedbal. The bullets are soft lead & lubed hollow base conicals of 280 gr. Nedbal gave me a

Priming the Thuer case

…and primed

Seating the bullet (1)

handful 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 her for smokeless! Once I found my routine of turning the tool forward and backward around the arbor loading these cartridges is a

Seating the bullet (2)

and here is my first Thuer cartridge using the 280 grainer conical

simple, straight forward operation. I have an idea now how the oldtimers felt sitting in the bunk house reloading Thuer empties yesteryear…


Shooting the Centaure Thuer –Range Reports

On the indoor range in Hofheim with the Centaure Thuer, August 27, 2008. Loading the 6 cartridges is easy (below left). Only very little force is needed to push them into the front of the chambers…1st round fired downrange from 25 meters…provides a solid first impression: nice boom, pretty thick smoke, significant but easy manageable recoil of the 280 grainers… (below right)

Loading the Thuer cartridges from the front using the loading lever

Historical moment: 1st Thuer round fired in Hofheim…ever?

Next 5 rounds fired in quick succession, quick recovery from recoil. Hits produced satisfactory POA/POI at 8 meters… (below left) and positive ejection of the shells after all chambers were emptied below right).

Recoil is easy managed

Positive ejection of the empties

It is a joy to shoot this Nedbal Centaure Thuer. She functions reliable most of the time if I do my part…but you have to pay attention to the details and don’t get over-excited… like counting your empties if you do not wish to end up with a “Thuer Magnum” like I did (picture below left). She 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

At 15 meters she is printing a bit high and to the left

Gave her another work-out November 26, 2008. Same charge of a full case of BP 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 280 grainers because 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 BP crud or cartridges or empties moving forward during recoil.

Pair of Centaure conversions: Thuer (top) Richards (bottom)

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. Because Bumble Bee could not pass on Nedbal’s Uberti Thuer and just had to liberate her for his cowboy armament. With these 2 types of bullets we could improve on our loading procedures, turned out properly seated bullets > 9 times out of 10 (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 is duplicating originals,

# 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 disassemble of the pistol 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.

Bumble Bee produces nice smoke and lots of sparks with CZ Jagdschwarzpulver V but little recoil only

The analysis of the velocity findings led to the development of a new 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 C&B cylinders of the pistols. 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 from 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)

Three comments: everything else being equal the slightly lower velocities recorded with bullets fired from the C&B cylinder can be explained by the different type of ignition used, whereas the comparatively lower velocities (and less kick!) from the Uberti are due to her bigger bore diameter. Although a crimp is not possible with Thuer cases heel type bullets with flat base can be seated much firmer into the case than HB or BB type bullets. In combination with the hotter CH1 this is accountable for the overall much higher 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 ideas why real cowboys preferred their contemporary Remington cartridge conversions or S&W Americans over Colt pistols of Thuer design. Or why they kept their battle proven C&B Armies and Navies. I feel these aspects are important because they add to the shooting fun but also bring the real life value of these different ignition systems into historical perspective.

# Thuers have potential for reasonable accuracy but ... there is 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 Centaure conversion cylinder (and Nedbal Uberti Thuer conversions for that matter) have their tapered profile all the way down from the front end of the cylinder to the breech end!

# During firing the conicals have no bearing surface, are not guided by the chamber walls, until they hit the rifling of the barrel because the front diameter of the chambers is greater than the rifling groove diameter of the barrel. Oversized bullets are no solution here. In my experience soft lead 195 or 200 grainers of heel type are the optimum followed by hollow based ones. Flat base bullets without heel cannot be recommended.

# The tapered cartridges are loaded from the front and kept in their chambers by friction only, like the empties. They might move forward during the action … from recoil … or when the pistol is carried on a person walking or riding … which can make cocking and firing difficult to impossible when the going gets tough.


WDN/February 11, 2009

© 2007 Wolf D. Niederastroth