Weatherby Japanese Semi-Auto Shotguns

Weatherby Centurion, Centurion II, model 82, Semi auto Japanese shotguns, Nikko, KTG

Weatherby Japanese Semi-Auto Shotguns

This will cover the Centurion, Centurion II, & 82 semi-autos
made from 1972 thru 1989

There are many photos in this article so load time may take a while if you are on dial-up

These semi-auto shotguns are discontinued & have been for years, with most parts being obsolete. We will deal primarily with the semi-autos here, however the pumps may be mentioned, as they a are a parallel gun to the semi-autos as they utilized many of the same parts. All these guns have the model designation engraved on the LH side of the receiver.

You may want to take a look at the exploded views page CLICK HERE as much of the nomenclature used by Weatherby on these guns do not match what we normal associate with US made forearms. They call the recoil spring links, carrier extensions, & the breech bolt carrier, simply a carrier.

The one part that seems to give the most trouble, is the slide assembly on the semi-autos, this will break, and welding usually is not successful. The main reason I believe, is that there was no provision for a recoil buffer in this firearm. Also we have found that possibly on a batch of slide arms that the factory may have manufactured them by cutting the material cross grain instead of with the grain of steel, resulting in a weaker part.

These firearms were made by 2 different manufacturers, with even a phase-in / phase-out overlap. We have not been able to find any differences in parts between the 2, as the firearms appear identical except the serial number prefix.

CENTURION - These guns used a aluminum receiver, ventilated rib barrel, & had a nicely finished checkered walnut stock that had a white line spacer between the rosewood grip cap. They used a non compensating gas system & used only the recoil spring in the buttstock to absorb recoil without a stop buffer in the rear receiver. The locking system & operating handle was quite similar to the Remington 1100. Fixed chokes in the barrels. The early versions used a single cast carrier extension that was slotted down the center allowing the hammer to extend up thru the extension when firing.

The wood forearm front was counter-bored to accept the magazine cap so the cap was not protruding from the wood. The magazine cap had detent notches on the rear side that a spring loaded detent in the forearm counter-bore interacted with to keep it from backing off.

Intermediate Centurions, as with s/n A04905, used the newer carrier machined for the (2) stamped extensions with a carrier extension that used two of the later single type ones. But they had a rivet at the rear holding the two extensions together. This configuration appears to be an intermediate version between the old one piece cast extension but fitted to the new carrier that had a machined spacer section to separate the extensions. However the way the riveted extensions are made, they could have been an early retrofit for the cast extensions IF a spacer was also used at the front.

The later carrier extensions were simply a stamped out sheet steel, formed as to made a RH & LH extension, with spacer (mentioned above) between then at the pivot point where they are attached to the carrier. This spacer separates these extensions so the hammer can move between them. These slide arms have only (1) set of alignments pin, while others have (2) at the silver solder joint to the dog-bone. Then later they eliminated the rivet, simply allowing the front of be pinned in place & the rear to nestle in the recoil plunger.

In the picture below, the bottom illustration shows a broken EARLY one piece cast Centurion carrier extension. The middle one is for a Centurion or Centurion II. The top one is for a model 82 as evidenced by the cut out in the LH end. This will be explained in the 82 section. You will note that these lower 2 have bevels on both edges. These extensions are shaped & beveled so they will slide inside the spring tube housing.

Wisner’s Inc. 306-748-4590, is making replacement Centurion slide assemblies. The Centurion II & 82 have a completely different slide assembly. Wisner’s makes a carrier that when used in conjunction with the Centurion slide assembly, will allow this Centurion slide assembly to fit and function in the Centurion II and the Model 82. They also make locking blocks, extractors, firing pins, operating handles etc. for these firearms, and some other discontinued Weatherby models.

The slide tubes for the Centurion have an overall length of just the tubing of 5.14". Some slide tubes have (3) equally spaced holes of .203 dia., back .600 center line from the front of the tube. The initial thought here was that it may act as an initial gas bleed off, but since the gas is trapped in the piston, this would not be the reason, so?

The gas piston has no writing on it so can be installed upside down, however the forearm can not be totally assembled if in this manner. The gas tube has a .065 dia. x .750 long retainer pin 1.535" in front of the tube's base that screws into the magazine tube. This pin keeps the gas piston from falling off during disassembly. The hole for this pin is in line with the (2) gas port holes.

The barrel for the 2 3/4" ammo has two (2) #37 gas holes. The magazine cap uses a bleed of representing a cross with the arms .095" wide & .330 overall length.

CENTURION ACTION SLIDE BARS - It has been noticed that the notches cut out on the bars (normally .500) on a few guns is a longer dimension .555+-. Known guns with the longer notches are s/n NA0094X, and another s/n NA0268X. One customer who has one of these low numbered guns & it is still unfired in the box, says it does not have a model on the end of the box, just “automatic”. These s/n would have put them as transition Centurions make by Nikko, while they were also being made by KTG, during 1973. It is not known exactly when the change may have been made to the later more common .500 dimensions.

Also on these early guns the slide bars were radiused on the rear. The Patrician used a LH slide bar that was angled off on the rear to act as a slide stop. This necessitated the need for 2 different bars in production. Later they simply used the Patrician bars on both the guns. However we have found that the first Centurions with the wider notch apparently needed the shorter radiused LH bar end.

In the photos above on the LH bottom is a Centurion slide assembly with a original carrier in position. Above it in the center is a model 82 & on top is a Centurion II slide assembly. Center photo shows the Centurion on the bottom & the newer type Centurion II & model 82 on top. On the RH photo you can see a good Centurion slide assembly on top & two broken ones below. The bottom one is actually off a model 92 as evidenced by the flat angled rear & the notch on the bottom on the RH bar. Most of the Centurion breakages are one or both slide bars will break off at the rear notches as shown above.

In the above Bottom Views photo, the top LH part is Wisner's conversion carrier which in addition to a Centurion slide assembly, converts to the Centurion II & model 82. Again in LH photo, left middle is a original carrier for the Centurion II & the model 82. Bottom of same column is an original Centurion carrier. Note the shallow groove lengthwise of it. This is the pad that cocks the hammer when the action cycles rearward.

On the RH side of the same photo are a broken model 92 on top with a original Patrician on the bottom. The part that is broken on the 92 is the thin web that is missing on the upper RH part of it.

In the above center views photo, the same parts are shown in same sequence as on the LH photo are shown, except flopped 180 degrees showing the top side view.

The RH photo shows the gas system of a Centurion II, with the forearm removed.

CENTURION II - The Centurion IIs have the same receiver configuration as the regular Centurions & will have that model engraved on the LH side of the receiver. Internally they are basically the same as the regular Centurions, with the exception of an "improved" slide assembly.

This improvement is not really improved except it was easier for them to make out of stamped parts. The tube was lengthened from to 6.14" & was silver soldered to the slide arm stamping. The normal breakage here is that the the stamped metal slide bars will break at or near the rear bend where they form a bridge & are connected to the carrier.

This gun also used a spacer of .233 front to back thickness & 1.157 dia. on the magazine tube, against the receiver's front. It appears this spacer acted as a dual stop, abutting against the rear of the slide assembly tube & the front of the receiver. This was timed so that the action bars are stopped at the same time the rear of the carrier hits the inside rear of the receiver. The forearm had a thin dual thickness C shaped metal liner of .500" glued into the rear of the wood. The dual thickness involved the thinner part to blend in with the forearm's inner hole & the rear thickness had a close fit over the above mentioned spacer. The above appears to be an effort to add a buffer system without a total re-design.

The carrier was changed to match this new stamped out slide assembly. The hammer was also changed to match the combo of the slide assembly & carrier. The hammer was made lower from the cocked notch to the cocking pad that the carrier rides over during the cycling action. A Centurion hammer (being taller) installed into a Centurion II trigger group will not allow the slide unit to move to the rear far as it can not go deep enough in the II housing & will bind things to a stop.

The Centurion II was made in either 2 3/4" or 3" barrels. The 2 3/4" barrels are the same as the corresponding Centurion barrels. We can not find any difference in the gas system between the 2 chamberings other than possibly the size & number of gas holes in the barrel for the 3".

The ejector is slightly different than the regular Centurions in that it's tail was shorter by .200 & it does not have longitudinal grooves of the #3205. The reason for the shorter ejector tail was apparently because these guns could have been had in 3" & this one part could function for either depending on the barrel it was fitted with.

MODEL 82 - These guns were introduced in 1982, so possibly the reason for this model designation??? These were made in either 2 3/4" only or 2 3/4" & 3" chamberings, with screw in chokes while still using the ventilated rib barrels. The 2 3/4" barrels use two (2) gas holes of #45 size while the 3" barrels use one (1) size #45 hole. Both use the same magazine cap which has a .250" dia. gas bleed off hole in the center. Barrels appear to be available from 26" to 30".

The screw in chokes were installed into a swaged up bore to accept the threading for these chokes. These barrels are swaged up from about .830 (depending on the length) to .905" at the muzzle to accommodate the internal threading for the screw in chokes.

The 82 receiver was again made of aluminum & was slightly modified to a semi hump-backed rear. Stocks were pretty much the same configuration & design as the Centurion series however they appear not quite as bulky. The forearm was shortened allowing the magazine nut to protrude forward, which made it easier to take down as compared to the Centurions.

The slide assembly was again "improved" but again using the stamped, bent sheet steel of the Centurion II but utilized a floating tube held in place by a wedge. The tube was shortened to 2.50" long. It is common for these slide assemblies to break at the pivoted wedge. Here the best repair is to silver solder the tube to the bar unit.

Extractors were the same as the Centurion series, however the plungers & springs were made smaller. Firing pins & springs were also changed.

Year	Mfg Weatherby model Serial Number range Gauge
1972 - 1974	KTG Centurion Auto AO00001 - A07405 12ga 2¾”
1973 - 1975	Nikko Centurion “ NA00400 - NA10091 “ “
1976 - 1979	Nikko Centurion II “ NA10884 - NA17754 12ga 2 ¾”
1976 - 1979	Nikko Centurion II “ NA10884 - NA17754 12ga 3”
1979 - 1981	KTG Centurion II “ A17755 - A18878 “ “
1982 - 1989	KTG 82 Auto 82-00001 - 82-11527 12ga 2 ¾”/3”
1972 - 1976	KTG Patrician Pump SO00001 - S05089 12ga 2 ¾”
1973 - 1975	Nikko Patrician “ N00001 - N00011 “ “
1973 - 1975	Nikko Patrician “ NS00500 - NS12863 “ “
1976 - 1981	Nikko Patrician II “ NSI2922 - NSI8148 12ga 2 ¾”/3”
1982 - 1989	KTG 92 Pump 92-00001 - 92-11990 “ “ “

We have recently seen pictures of a Nikko Super Express 7100 12ga in serial number range of J0039X that appears to be an almost exact copy of the Weatherby Centurion.

Different carrier extensions	Shown on top is Wisner's conversion unit for the Centurion & model 82

	Shown immediately above is a broken slide assembly off a model 82

Slide assemblies for 82, Centurion II, & Centurion	Differences between model 82 on top & Centurion , Centurion II slide bars	Good Centurion on top, center & bottom are damaged units

Bottom view of carriers, both semi-autos & pumps	Top view of carriers, both semi-autos & pumps	Centurion II gas system with forearm removed

Model designation on receiver of Centurion II	Top illustration is a model 82, with the bottom being from a Centurion & Centurion II