I say the prosecutors should show some compassion and only ask for a moderate penalty in this case:
In a nationally televised interview examining the place of gun control, NBC’s David Gregory may have violated the District’s gun laws.

The law (DC ST § 7-2506.01) says:
b) No person in the District shall possess, sell, or transfer any large capacity ammunition feeding device regardless of whether the device is attached to a firearm. For the purposes of this subsection, the term “large capacity ammunition feeding device” means a magazine, belt, drum, feed strip, or similar device that has a capacity of, or that can be readily restored or converted to accept, more than 10 rounds of ammunition. The term “large capacity ammunition feeding device” shall not include an attached tubular device designed to accept, and capable of operating only with, .22 caliber rimfire ammunition.
I had difficulty tracking down the punishment but it appears this could be the potential outcome (DC ST § 22-4515):
Any violation of any provision of this chapter for which no penalty is specifically provided shall be punished by a fine of not more than $1,000 or imprisonment for not more than 1 year, or both.
It appears (I am not a lawyer!) this might also apply (DC ST § 22-1805a):
(a)(1) If 2 or more persons conspire either to commit a criminal offense or to defraud the District of Columbia or any court or agency thereof in any manner or for any purpose, each shall be fined not more than $10,000 or imprisoned not more than 5 years, or both, except that if the object of the conspiracy is a criminal offense punishable by less than 5 years, the maximum penalty for the conspiracy shall not exceed the maximum penalty provided for that offense.
(2) If 2 or more persons conspire to commit a crime of violence as defined in § 23-1331(4), each shall be fined not more than $3000 nor the maximum fine prescribed for the offense, the commission of which was the object of the conspiracy, whichever is less, or imprisoned not more than 15 years nor the maximum imprisonment prescribed for the offense, the commission of which was the object of the conspiracy, whichever is less, or both.
Since it is a victimless crime I say prosecutors should fine everyone involved $500 and six months for the possession and $500 and six months for the conspiracy. I’m opposed to victimless crimes in their entirety but one of the ways to get rid of such laws is to prosecute them vigorously. Half the maximum penalty sounds about right to me.
Say Uncle (with more links here and here) and Sebastian also have some thoughts on the topic.