Firstly, why would you want to reg a MPR FT?. I owned one and it was the most consistent rifle I have ever had at only 3fps spread, against 9fps from my EV2 MK4 and 12fps from my new Steyr 110.
I did have a few mods on mine, FAC length cylinder, UK Neil muzzle flip and a custom stock.
My advice would be (if you bought an MPR) to test it over the chrono before even thinking about getting it regged, if its consistent then leave it, by fitting a reg does not guarantee consistency, and is something else to go wrong.
I fitted the long cylinder on mine in the hope of getting it regged, but it was so accurate and consistent that I didn't bother.
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