I've waited until the conclusion of this incident to post here, and it came today.
On New Year's Eve, I was pulled over in Cooper Landing for "no trailer lights". They were working, but that is neither here nor there.
The Trooper was polite and courteous, and explained that this stop was due to increased enforcement and visibility during the holiday. I informed the Trooper that I had firearms (within reach of me), and he secured them for the duration of the stop. One of the firearms, an AR style pistol, was fitted with a Sig Saur forearm brace. Those of you who are interested in such things know that it is a firearm brace, which to some, look like a butt stock. However, it has been approved by the ATF as long as it is used as designed, and not shouldered. The Trooper let me go during the traffic stop with only verbal warnings, and was again, very courteous and professional.
The Trooper took a picture of it, and showed it to an AST firearms instructor. 2 days later, he called me back, and sternly informed me that the brace installed was illegal, and I needed to remove it or face seizure and possible arrest. He said "I don't care what letters you have from the ATF, it's illegal" (paraphrased by me).
Feeling myself on solid legal ground, I wrote a letter to the SOA AG, and the DPS commissioner explaining my case, and asking (politely) what the opinion of the SOA was.
To their credit, a LT in the AST (FWP) called me and assured me he would look into it... Today said Lieutenant called to inform me that I was right, and education of the troopers would be forthcoming.
I would advise anyone with said Sig Brace to carry a copy of the ATF letter with them to alleviate any future questions.
Although I have to admit I was very frustrated with the troopers at first, I applaud their leaderships' willingness to follow through and get to the right answer.