Just got a +4 extension for my 11-87 20 gauge. Installed it and found that I can only load 2-3 shells. The spring from Choate seems way long. Any help about this...how long should it be? Assuming this is the problem.....

Did you replace your shell follower with the Choate hi-visibility follower?  If so, try this right quick-switch back to your original follower and keep the choate spring and extension on the gun.  On my 870, the Choate follower would sometimes bind up and prevent me from loading to capacity.  I had to make it a little smaller in circumference to funtion correctly.  Hope this helps-ARKAR.

Remember also, magazine extensions are usually sold by the number of TOTAL shells they add, INCLUDING one in the chamber.

So if you have a +4 extension, it usually means the tube holds 3 with the 4th in the chamber, so the gun should hold 7 rounds in the tube itself.

The Choate magazine springs are ALWAYS the correct length, so DON'T cut it off or the gun will malfunction.

Also, make sure you remove the factory installed magazine plug.  This is the green plastic rod that's usually in the magazine and is put there to meet Federal regs for Migratory Bird hunting.