I have been checking into this, ALOT. EAA no longer sells the mag extension. There is a company in New Zealand (www.guncity.co.nz
) that sells them for about $85 shipped to the US. It is a 3 round extension. I am in the process of making a few of them though. I am getting the steel end caps from EAA and welding a +4 size piece of steel pipe. With the spring and barrel clamp, I might start to sell them for $45-$50 if there is enough interest (assuming the buyer waives all liability, etc...) I will have the first ones done this weekend and will post pictures early next week. EAA sells the sttel end caps for $14 + $7.50 for shipping. Tehy can send me up to 10 for the same shipping price. I will let you all know more after the weekend. I look to get $20 + parts and shipping. Let me know if you are interested..