What exactly does the DNR mean by " No long barrel modifications"? I have been considering a T/C Contender (G2) or Encore pistol registered frame and at least one barrel (14"or 15" most likely) in an allowed caliber.
i talked to the "law enforcement" area of the Iowa DNR and it was explained to me that the "no long barrel modification" is meant simply to detour anyone from buying a long barrel, for example 24" and cutting it themselves back to say 16" or 18".
today, the state of iowa doesn't have a maximum barrel length clause. if you head out to the tree stand with a T/C pistol armed with a 26" barreled 50 Beowulf, you are legal.
in a nutshell, if you buy it and have a receipt for it, you are legal. if the DNR can verify your source as a business you are legal. they don't want weekend warrior gunsmiths hacking things up for people to use during the hunting season.
if this is a problem for you i'd suggest a custom barrel from e. arthur brown co - minnesota. he can make one in about any caliber and any length. i have heard quite a few people remark at their satisfaction with him and his products.
hope this helps. if not, read my signature disclaimer...