Thought I'd put these dates here also,,,,,
Mossberg 500/835 acton slide tube changes
Action Slide Tube Assemblies Lengths: There are two different action slide tubes (forend tube) used on the 500 (all gauges) and 835 pump action shotguns. It is imperative to know the length of the original when replacing the action slide tube or the forearm as individual components.
Prior to 1973 all action slide tube assemblies utilized tubes with a length of 7-¾". In 1993, running production changes commenced to change over to a tube with a length of 6-¾" in all gauges. The change will typically found in the Model 500's with serial number prefix K3 and Model 835's with serial number prefix UM or higher (K4, K5; UN, UO). There is an exception: All Special Purpose, Persuader and Cruiser produced to date still use the 7-¾" action slide tube assembly.
The current production 6-¾" action slide tube assembly, with appropriate forearm, may be used on models previously using the 7-¾" action slide tube. In some instances modifications will be required as noted below.
Single Arm Action Slide Tube Assemblies: Early production Model 500 shotguns utilize an action slide tube assy. (forend tube assembly.) with a tube length of 7-¾" and a single action arm. This tube assembly is obsolete. A twin bar action slide assembly with a tube of the appropriate length may be used as a replacement for the obsolete single arm action slide assembly. If both the action slide tube assembly and the forearm are being replaced, they may be replaced with either 7-¾" or 6-¾" action tube assemblies and matching forearms as available.
G Serial Number Prefix: All Model 500 shotguns with a G serial number prefix utilize a specific magazine tube with a ring system around the external diameter of the magazine tube. This utilizes a specific action slide tube assembly. Both the magazine tube and action slide tube assembly for this variation are obsolete. If replacement is required both the magazine tube and action slide tube assembly will require replacement. The 7-¾" or the 6-¾" assemblies and magazines tubes, current at the date of this publication may be used as replacements. Insure that the length of the tube matches the original forearm or replace the tube and forearm with matching units.
Mossberg 500/835 acton slide tube changes
Action Slide Tube Assemblies Lengths: There are two different action slide tubes (forend tube) used on the 500 (all gauges) and 835 pump action shotguns. It is imperative to know the length of the original when replacing the action slide tube or the forearm as individual components.
Prior to 1973 all action slide tube assemblies utilized tubes with a length of 7-¾". In 1993, running production changes commenced to change over to a tube with a length of 6-¾" in all gauges. The change will typically found in the Model 500's with serial number prefix K3 and Model 835's with serial number prefix UM or higher (K4, K5; UN, UO). There is an exception: All Special Purpose, Persuader and Cruiser produced to date still use the 7-¾" action slide tube assembly.
The current production 6-¾" action slide tube assembly, with appropriate forearm, may be used on models previously using the 7-¾" action slide tube. In some instances modifications will be required as noted below.
Single Arm Action Slide Tube Assemblies: Early production Model 500 shotguns utilize an action slide tube assy. (forend tube assembly.) with a tube length of 7-¾" and a single action arm. This tube assembly is obsolete. A twin bar action slide assembly with a tube of the appropriate length may be used as a replacement for the obsolete single arm action slide assembly. If both the action slide tube assembly and the forearm are being replaced, they may be replaced with either 7-¾" or 6-¾" action tube assemblies and matching forearms as available.
G Serial Number Prefix: All Model 500 shotguns with a G serial number prefix utilize a specific magazine tube with a ring system around the external diameter of the magazine tube. This utilizes a specific action slide tube assembly. Both the magazine tube and action slide tube assembly for this variation are obsolete. If replacement is required both the magazine tube and action slide tube assembly will require replacement. The 7-¾" or the 6-¾" assemblies and magazines tubes, current at the date of this publication may be used as replacements. Insure that the length of the tube matches the original forearm or replace the tube and forearm with matching units.