Shot my 42 Izzy sporter that you've all seen pictures of on here yesterday to verify my drop after installing the muzzle brake a while back. It really didn't seem to changet the drop of the bullet any. The location I shot at yesterday only allowed me to shoot at 472 yards. After running all the numbers through my ballistics program I seemed to have maybe lost around 25 fps. Not exactly disturbing but a difference. More shooting will tell. I only shot maybe 15 times. I didn't even count. The gun seemed to group pretty well cold but then opened up with each shot. I did not allow any cool time between shots. I shot 3 times, then allowed some cool time then 3 more and so on. I also shot some Hornaday HPBT .312" 174 grain and saw very little difference in point of impact or grouping. The Hornaday had a slightly lower impact of maybe 4" but still moved up and slightly to the right with each shot as did the SMK.
Target and shots:
Target is a 12"x12" steel plate at 472 yards
You can see a 5 shot group that is really tight near the center, then 2 shots close to each other about an inch or so higher and to the right. then a couple shots right at the top of the plate.
The 5 shots are cold bore. then the 2 higher are 2nd shots, and the ones at the top of the plate are 3rd shots. I'm pretty sure that is correct but not totally since I was spotting for myself. I made this gun for a sub 500 yard deer gun so I'm happy with it so far for that. It is a blast to shoot further though when I have time. I plan to do a comparison test later with the brake on and off to see if there is a definate group difference or not.
Here's the target