User blog comment:Argorrath/Treyarch confirms that there will be no more gun DLC/@comment-68.113.195.134-20130413182148/@comment-25496444-20130415225456

4. Engine can't handle

A friend of mine actually told me that a developer at Treyarch once said that one of the reasons that CoD doesn't offer DLC weapons is that the engine has a hard time loading it all. Can't say for certain, but this could also be a pretty important reason.