I am the one Rustam is referring to. I noticed when using the AA plenum insert silencer, my groups were significantly bigger than without a silencer or with the Parker Hale silencer.

I started cutting pieces of the plenum silencer and with each piece I cut away, the grouping became a little bit smaller <!--graemlin:-->. At the end, I only had the threaded part of the silencer left <!--graemlin:--> and the grouping were OK again, but the silencing part was not that good anymore <!--graemlin:-->.

I ordered another AA silencer to see whether it was the silencer which was faulty, but got bad groupings as well with the new AA silencer.

I yet have to try in on a friend's gun to see whether it's caused by my gun. Anyone had similar experiences ?

Below are some grouping shot at 25 m (27.5 yards), the outer circle is 1". As you can see, with the PH or the modified AA silencer, groupings are easily below 1/2", but with the "normal" AA silencer, groupings are much wider.