Thats unfortunate to hear. I would have guessed by the way they never show close ups of their guns. Im sure in real life it might not look that bad at 100 feet or more either. But once you get close up it should be obvious that somethings wrong.
You could try putting a mechbox in the MG42 ruger 10/22 kit. I was thinking about going down this road myself. But I gave up on the idea once I found out that the kit is 2/3 scale. Or would be the same length as a M4. Wouldnt look right holding a miniature MG42.
The kit is listed here. Scroll down.
http://www.deltaforce.com/catalog/1022.html