First let me say that I am very happy with my MGSL and dealing with Mr. Graham. Fast shipping and no worries.
I shot for groups of 5 shots before I installed the item and recorded the results. I installed it and then I shot for groups again. Since then I've shot it practicing and doing a steel shoot and put about 600 rounds down range. At around 250 I recorded some groups and here again at 600. Now, let me preface this by saying that I'm not a good shot. I'm using a red dot because of my aging eyes. I shot all the groups recorded off sandbags to take out as much operatior error as possible. I'm shooting at 15 yards using WWB from Walmart for all results.
The initial groups with it installed were not that different from the groups without it installed. Pretty much what I was told to expect. The groups were about 2.6" average from 6 groups. The 5 groups at 250 rounds averaged out at 2.3". On the 25th of March (600 rounds through the gun with new MGSL) the 8 groups of 5 shots ranged from a low of 1.125" to a high of 2.625" for an average of 1.86". If I throw out the low and the high group it averages to 1.854.
Now, I have no idea if my shooting skills are good or bad. Perhaps a good shooter will do a lot better. I also don't know if I just improved shooting groups. Guys at the range will say "Hey, that's great." I can't figure out if they are being polite, great shooters or if they can't shoot very well.
I do know this: My Ruger 22/45 Target will shoot under an inch all day long with the same circumstances. I know that won't happen with my 34.
All in all, I have to say that the MGSL from Mr. Graham has been a welcome improvement. Well worth the cost.
Now the big question. Is 1.854" at 15 yards good for a Glock 34? Is it good for a 9mm? Is it good for a anyone?