Turkey broadhead recommendation for a crossbow?

Haven't posted on the forum for a while, but something has come up where I really need help. Do any of you have a recommendation for a turkey broadhead (guillotine style) on a Mathews MXB crossbow? Here's the reason I'm asking:
I used to use Montecs for both deer and turkey, and was pretty successful with both. Last summer, I bought my new Mathews crossbow, and this past deer season I switched over to Spitfire mechanical broadheads, since that's really the only type of broadhead that works in my crossbow (because the Mathews crossbows have such a narrow rail on them). The Spitfires worked great on deer and hogs. Anyway, yesterday I finally snuck off to the woods to go turkey hunting for the first time this season. Called in a big jake, and I plowed him with my crossbow bolt at 13 yards. I knocked him flat on his back! Problem is, two seconds later he immediately jumped up and started walking away like nothing had happened. I couldn't believe it! He finally ran off, and didn't have a problem with getting around either. I sat there in total disbelief, wondering what happened. The only thing I could guess is that the broadhead never expanded when it hit the turkey, and obviously wherever I hit on him was not in a vital organ area.
So, this has gotten me to thinking...either use a guillotine style turkey broadhead that will lop his head off if one gets that close again, or use another turkey-specific broadhead of some sort. I know Spitfire does make a "turkey broadhead" that looks just like the ones for deer, but I have no idea what the difference is between the two. Anyone got any ideas? I was totally bummed out losing that turkey yesterday, and I surely don't want to do that again when I go out hunting again this weekend.

Use the largest surface area tip you can find.. We're did you hit him? I'd aim for back 1/3 of the body right were the leg would meet it.. That's were your vitals are

He was facing directly towards me, and wouldn't give me a broadside shot, so I aimed for his beard, which is where I was always told you aim with a bow when a turkey is facing you. I'm thinking he may have gone to turn to his right when I shot him, and if that's the case, then chances are good I probably hit him in the breast, which is not a killing shot. I normally like to shoot them when they are broadside, but I didn't have the option.