JBensyl,
I have my form 1 approved and in hand. I'm now awaiting delivery on my C parts kit. I put an overall length at 28". I think it's just over that, but as long as you write in a length shorter than actual it's ok. You might want to check with others if you are supposed to give the length with the stock folded, though. I didn't, since I am not allowed to have a folding stock here in CT. so I have my stock permanently locked. I'll take another measurement tonight, but if all you need is the dimensions when locked, I think your ok with putting 28"
Scottoe