Thread: 300 Blackout Suppressor - fixed the bastard...

The inaccuracy of my Blackout with Sub-sonics has been the subject of much head scratching. I built up a load that cycled well and was pushing 240 SMK's at 1020 fps. My suppressor is an over-barrel one built by Goodwin Prototyping and it looked nice enough, and was quiet, but every time I spun it on, and tried it, the POI was low and left, 7:30 on the clock. I initially sent it back to them as I suspected I was getting internal strikes, and to have the rear bushing redone. They sent it back with a note to say there was no evidence of strikes, and a new busing was fitted.

Today I finally got around to debugging it myself, as it was still giving me a very low left POI. I should point out that without it, I coud zero with subs or supers and the groups varied only in elevation, no windage factor.

I fired a group and got a string of hits from the POA on down to the left. I the unscrewed the suppressor half a turn and got two hits high and right... Here's the target. Ignore the .22 stuff.


This pretty much convinced me I was getting internal baffle strikes so I decided to pull the suppressor apart. Some heat on either end with the blowtorch took care of the loctite they'd used and I was able to pull and inspect the baffle assembly. Here's what I saw...


Quite obvious copper smears in there...

It looked like the bore through the baffles was slightly over 8mm. I ran a 8.5mm drill through from both ends, cleared out the swarf, reassembled and shot and a reasonable group but it was still low and left. At least the group size was encouraging but still being interfered with by the suppressor. I then opened it up with a 9mm and test fired. With no scope adjustments, the POI was immediately back to near centre. A few clicks brought the group up to the aiming point.
Here's the target, the 5 shots about 8" away at 7:30 are after the first rebore. The ones about 1" away at 5:00 are after the 9mm rebore and with no scope adjustment between those groups.



Damned thing has been bugging me for ages but I'm happy I've got it sorted now.