Alternative Blunderbuss Rules

After a couple of games using stand in models a while ago it became obvious that the Blunderbuss rules were unweildy and generally not good.  I have read a couple of alternative rules in fan-made army books but they don't seem to keep the chracter of the weapon.  I can understand wanting to increase ranges or other things, but the whole idea behind the blunderbuss is that it is a devesating but short-ranged weapon; a range increase has to effect the impact the shots have.  I liked the "cloud of shrapnel" effect for the Ravening Hordes rules, but the number of hits inflicted wasn't affected by the number of troops firing and that seemed very odd to me (surely more people fireing doesn't make the shots stronger/go faster).  I've done a bit of testing with the rules below and they seem to work well.  Units are very effective at close range against massed troops but very ineffective at longer range or against tougher targets - which is how I think a blunderbuss should be.  The rules I am now using are:

*edited on advice from Sparrow*
May move and fire.
Strength 3.
Each successful roll to hit causes 2 strength 3 hits.
Armour Piercing