http://i43.photobucket.com/albums/e4...ps3e884e5c.jpg

416D AOR waiting clearcoat

What is the optimal barrel length where there is no more performance gain?

Depends on alot of factors.

M4 is the maximum length (373 mm) in a Systema. Assuming the barrel ID is consistant, and that the hopup is the best performer available, and the cylinder is well maintained and consistant.

I have very good success with the CQBR, that is all I use.

Most feedback from PTW users say they get better results with a 7.5" barrel than a 14.5" barrel.

I can confirm this as false, with testing of various barrel lengths with the same hopup type. The 7.5" was consistantly the worst performer, with range at 225 feet vs 250 feet with 10.5", and velocity consistantly 30fps less with the 7.5", regardless of the cylinderin velcoties from 330-530 fps.

The consistantly best performer is Jonas's 14.5" PDI barrel with modified hopup. It is a tackdriver and he can hit out to 300 feet reliably.

7.5" are mostly used for CQB engagements, for outdoors stick to 10'5 or 14" anything more than that is a waste