| In the year 2000 Beretta introduced the 12-gauge Optima barrel design into some of their competition shotguns. This new barrel utilized a larger internal bore dimension known to some as "back-boring" and required a new choke tube design to give the proper constrictions. The Optima barrels can be identified by locating the letters "OB" stamped next to the barrel gauge stamp. The Optima-Choke design also featured a longer internal taper, just ahead of the choke constriction, making the overall length of this tube longer than the original Mobilchoke tube. A key fact is that Optima-Choke tubes will only be found on 12 gauge competition Optima shotguns. Optima-Choke Plus
With the introduction of the model 391 Xtrema shotguns in 2003 the Optima barrel configuration was added into the 391 12-gauge line of field shotguns. In order to handle a higher volume of steel shot shells used in field hunting, the Optima-Choke tube was revised and manufactured with a thicker wall size. This revised choke tube was named the Optima-Choke Plus and featured the same Optima-Choke internal dimensions and performance but has a larger outside diameter and revised thread location. A key fact is that Optima-Choke Plus tubes will only be found on 12 gauge field Optima shotguns (*except 471 Silver Hawk).
Other Specifics
Each of the above choke tube types is designed for use with a specific type barrel and as such features different thread locations and external measurements, none can be interchanged with the other Beretta choke types. Every Beretta choke tube has information engraved on the tube to identifying the manufacturer (PB), the constriction (F, IM, M, IC, CYL), the approval for steel shot use (SP) and the choke type (Optima-Choke, Optima-Choke Plus)
Within each of the three choke types, different variations of length and finish are offered. The length variations available for each type is flush fit or extended choke tubes. Most field shotguns are equipped with flush chokes. Sporting and skeet shotguns will be equipped with extended tubes. The Beretta factory may supply trap guns with either choke variation as determined. Within the extended choke variations Beretta offers two finishes. Since the extended chokes are exposed past the shotgun muzzle they offer choke tubes with a black non-reflective finish for hunters. A bright finish tube with colored bands is offered for competitive shooters, this band allows easy identification of the tube constriction.
It should be mentioned that two other choke types saw a limited use. Supplied with some 302 and 303 models shotguns was an early version of the Mobilchoke where the tube body was not threaded but smooth. This type tube was dropped into the muzzle end of the barrel and secured by collar threaded onto the barrel muzzle. This tube type is no longer available from Beretta. The second type was offered on an early version of the DT-10 shotgun made specifically for trap, this shotgun was known as the Vandalia model. These tubes are similar in size to the Optima choke flush tube but are not interchangeable with them.
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