If you want to convert your Mossberg 500A (12 gauge) to a 14” barrel—legally, of course—you will need to order a total of eight front-end parts from Mossberg. Give Mossberg Customer Support a call at 1-800-363-3555 and order one each of the following:
|13488||Tube Nut 500A/835||$8.53|
|11239P||M590/835 Mag Cap Parkerized||$14.00|
|12410P||Magtube M514 Parkerized||$14.00|
|12392P||Magazine Spring Retainer 590/835 Parkerized||$3.50|
|12194||Spring, Magazine 835||$3.50|
|16033P||Bbl Asm 514Bead Hvy/w Parkerized||$100.00|
|12362P||Action Slide Asm 500/514 Parkerized||$22.00|
Prices listed above were current as of March 1, 2015. With shipping, the total was $196.56.
Recently, I heard that Mossberg now has a part number for the whole front end assembly: 92514. You can now call up and just give them that number, and it will get you one of everything on the list above.
You can then probably sell your original front end online for anywhere from $75 to $200—and recoup a significant part of your costs of upgrading to the uber-cool 14” front end. All NFA rules apply, of course.