Item #12946, 18.5" cylinder bore w/bead sight, blue finish [$100.00 as of Jun 2013]. The #12946 is a true cylinder bore, smoothbore barrel, NOT AN OVERBORED BARREL, and both slugs and shotshells (2.75", 3", and 3.5") can be fired through it.
The #12946 can [no longer be] ordered parkerized for $20 extra. Barrel #12946 is the same as #90823, which is the part number of this barrel when it is sold to stores in clamshell packaging. Contact the Maverick Arms Product Service Representative directly at 1-800-363-3555, ext 541.
The 835 security barrels in stock are all blued. They used to accept an order to make one one from scratch and parkerized it. I quote my Maverick Arms Inc. invoice, "Sales Order 6034602, dated 25 Jun 2010, order date 22 Jun 2010. SKU# 12946. Item Description: BBL ASM 18CBBS BLUE. Unit Price: $120.00. Total S/H charge: $8.95. Total Invoice Amount: $128.95." Now regardless of the word "BLUE", the price was $120.00, whereas the price of the blued barrel was $100. The $20 difference was for parkerizing.
Customer Service since 2013 has incorrectly claimed that parkerized 835 security barrels were never available.
No one should ever load or fire a 3.5" shell in a 500A barrel, or they and the barrel may blow up. A crimped 3.5" shell will fully chamber in a 500A gun with a 500A barrel (with the safety on!), when loaded at an angle through the shorter ejection port, as well as in an 835 gun with a 500A barrel. It is conceivable that someone in the future could try to shoot a 3.5" shell without reading the 500A barrel warning, trusting that the gun is an 835. I am opposed to 835/500A/590/590A1 barrel swapping, and so is Mossberg.
Mossberg Owners Manual for 500®, 505™, 535™, 590®, and 835® Shotguns wrote:
Barrels are not interchangeable between model numbers, gauge or capacity. 500®, 505™, 535™, 590® and 835® barrels are interchangeable only with barrels of the same model, gauge and capacity.
I felt stupid for trying that experiment when it seemed that the live 3.5" shell could not eject because some shell still remained in the 500A chamber, but fortunately it did eject without setting off the primer. The crimped 3.5" shell is 2-7/8". I was trying to save myself the trouble of attaching a 500A barrel to an 835 to see if a 3.5" shell will fully chamber.