I think a repeating breach on the AR2078 would be sweet. I have found 2 similar ones in the UK.
GMAC
http://www.gmaccustomparts.com/epage...cts/QB-RIM1-22
and Rowan
http://rowanengineering.com/products3.htm

Are either or both of these any good? pros and cons?
I believe JRA used to make a decent repeating breach, but no longer produced.
Thanks for any info.

Here are some groups shot with my 2078 Fitco scope 12x @ 10m - JSB Exact Jumbo RS - 5 shots on each target (12mm black circle). First two top left before fine tuning scope - scope adjusted on the third from left top. I got just shy of 60 good shots on bulk fill you can see the last 3 shots on the last target falling low. Looks like gas efficiency improved by the polishing/reseal job! And look... no flyers.
AR2078 10m scoped.jpg