870 barrel replacement

[#1buck]

I have a clarification question. Recently I was looking a for a hunting barrel for my 870 tactical 20577. While checking out barrel options I found it mentioned that certain years of the model 20577 would not accept field barrels. From what I understand the model shown in image (A) below with a two piece mag tube (4" with a screw on 2'") will accept most barrels. Where as the model in image (B) with a one piece mag tube is limited to a specific barrel type. Do I have this correct? The 870 Model 20577 I own is like the one in image (A) with a two piece mag tube. I purchased it in 2011. I need to clarify this before I purchase a barrel. I would appreciate some input. TIA

[efriedrich]

You are correct, image A will except other barrels by virtue of the location of the barrel ring being at the end of the four round magazine tube. If you notice the barrel ring in image B, it extends past the barrel nut in image A making it unable to be interchanged with most other barrels. The object that is circled in image A is a removable barrel clamp used to support the extended magazine and doesn't have anything to do with barrel compatibility.

[#1buck]

Thank you kindly for your response.