I had responded to Roy off line via e-mail and basically told him the same thing you are saying. I didnít post it because I felt it would turn into an argument instead of a discussion because most people have never heard of this.
I have heard this for many, many years and have read many articles about it, and all said the same thing. Scopes can be damaged by a muzzle brake
equipped rifle for the reasons you state. I wish now I had kept the info but I didnít.
Most people would also say youíre crazy if you tell them an air rifle will damage a scope but it is a very serious problem. Maybe they need Nightforce scopes on their air rifles.
I have seen 2 scopes that were damaged because of this. Let me say that both were what I would call inferior scopes. Both scopes had been used on the guns prior to having the brakes installed with no problems. Both guns were in the 300 mag to 338 mag class. I have never known a high end, quality scope to be damaged and therein may be the problem. Most people that frequent this and other similar boards tend to gravitate towards the upper end equipment so would probably never have a similar problem. I suppose it could happen to a top end scope but not as likely.
I donít think Royís scope is damaged, but it slipped. It hadnít slipped prior to the brake being installed so I would feel that the additional, increased forces created by the brake caused the ring to scope contact to go away and allow the scope to slip. I agree about trying different rings etc. I doubt he would want to try it, but he could remove the brake, make sure everything is tight and try it. Then re-install the brake and see if it happens again. Just my $ .02 worth.