Another 870 question

[AC's & 45's]

Hope this doesn't come across as stupid. No stupid questions, Right?
If I buy a new 870 Express the receiver is marked 2 3/4 and 3". Does this mean I can use either in this barrel. Or, does this marking only refer to the receiver and I will need separate barrels. If the chamber is cut for 3" will extended use of 2 3/4" harm it?

I never had this come before up since I have only used an old Wingmaster in 2 3/4 till now.

Also, should both 2 3/4 and 3" feed and chamber with equally reliability?

 

[btm]

If you are buying new you shouldn't have a problem with 2 3/4" or 3", yes both will load and function fine.

Used gun that is receiver marked magnum 3" make sure that the barrel is also 3" mag. barrel. Actually an old
2 3/4" and a newer 3" mag. receiver are the same strength, the only difference is the placement of the ejector. An old receiver can be converted to a 3" but is not cost effective. Cheaper to buy a nwer style 870.

BTM

 

[Dave McC]

No stupid questions.

Any shell can be safely fired in a chamber of a length longer than the nominal shell length. I say nominal because a 2 3/4" shell is that long only after firing, not before.

This means that in a 3" chamber, you can shoot 3", 2 3/4", 2 1/2", even those itty bitty 2" Brits loads safely. And, they will pattern effectively. THE REVERSE IS NOT TRUE!!
3" shells that are fired in a 2 3/4" chamber are not good for you or the shotgun. An 870 will handle it,probably, but I cringe at the thought.

2 3/4" loads in a 3 inch chamber will shoot fine.