Yes, in my personal experience and in all but one case I have read/heard about, people are saying the block reduces accuracy. I read of one second hand account where someone said his buddy kept his on becuase he found it more accurate with it on, but being second hand, I'm not really inclined to believe it....
The problem is really the way the handguard is mounted. It is attached to the reciver below the barrel, and the block is below the barrel, so the barrel support block cannot possibly put as much upward pressure as is needed for the block to be effective, in essence, they have taken a setup the REQUIRES a rigid connection between point A (the reciver) and point B (the support block) and made if flexible. What happens is as the handguard screws are tightened, the barrel support block pushes against the barrel, but the barrel is more rigid than the handguard, so it flexes slightly (the handguard mount) and then when you rest the handguard on your hand (or anything else) it adds a little more upward pressure, moving the barrel slightly... Its all but imperceivable to your eyes, but can throw you off several inches at 100 yards....
I took my block out after my second time shooting my SR-22 after noticing that I could move the barrel by pressing on the handguard, and accuracy was improved a LOT....
If you want a stud mounted bi-pod, simply sand down the barrel support block so it doesn't touch the barrel.
