Quoted:
Hey folks, I have a 1300 that was my grandfathers. Problem is none, and I mean NONE of the factory chokes make this gun kill like I think it should. I shot 9 times to get 6 squirrels and I had to do the "run & stomp dance" with over half of em. My father on the other hand using an old model 12 with same ammo, same squirrels, same basic ranges and the rats drop like bricks. I dont like injuring game and I dont like dispatching said game with my good boots. The only difference I can think of is the chokes. The 1300 has changeble chokes while the 12 dosnt. Any of you fine upstanding citizens found a choke that works really well in your 1300?
There is your problem, assuming you have a tight choke like at least a Modified in the gun and you don't suck with the gun. OEM tubes can be off by as much as one full choke size. So even if it says Modified, in your gun it may truly be IC. Go to a club or a smith who has the tool needed to measure both the barrel bore and choke diameters. Then you will know what to buy in terms of the proper choke tube to get the desired choke.
Like said above, you should also pattern it.