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.
I would concur with Kirby. The opposing shear forces produced by a brake are huge. Scope manufacturers ( I know a couple ) claim that a good brake on a large high preasure magnum rifle produces shear forces of double, or better, than the same rifle without a break. The rifle starts a recoil pulse the moment the ignition occurs. The rifle starts to move rearward only to be counter acted by gas preasures pushing forward in the break, This creats the same difference as a car running into a wall, or another car head on at near the same speed, the difference is huge. This is also the same reason that the recoil spring rates for a 38 super 1911 pistol with a break are half of one without a break. The bottom line is as Kirby has recommended, a stronger mounting platform is needed.
Hey guys, sorry to hijack but I am about to put a leupold long range target on a braked 300 RUM that kirby is finishing for me. What base and rings would you suggest that would be substantial enough for this beast?
my understanding of why a heavier bullet kicks more is because of more primary recoil, that being more energy to get it up to speed. and second,the chamber pressure is higher when the bullet exits due to more barrel time and generally speaking,slower burning powders.i knew there was a forward push on a gun using a baffle style brake,but i will admit i didn't realize it was enough to actually move the gun forward.i understand now what you mean by more stress put on the scope because of getting smacked in both directions.as far as the rearward movement of the scope,it comes back with less force using a brake.
I will be range testing your rifle with a Burris one piece standard base with a set of Burris Signature rings and a Weaver Tactical 4.5-14 scope.
The reason the windage adjustible base with standard screws often fails under heavy recoil or with a muzzle brake equip rifle is very simple.
When you have a mounting system like this you basically have the front ring doing the work and the rear ring being the pilot.
By that I mean that the front dovetail ring has about 80% of the work involved in keeping the scope sitting still under the strains of recoil. The rear ring which is clamped between the windage adjustment screws does very little as far as keeping the scope from slipping and the grip of the windage screws is totally inadiquate for this purpose.
They are there to offer you windage adjustment and thats about it.
When the front ring looses its grip, the rear ring will do very little to keep the scope from slipping. Often the rear ring does not loose grip on the scope body but instead it slips out from between the windage base screws.
The same system using the Burris signature rings is no differnet in that the front ring does 80% of the holding work keeping the scope from slipping. The only difference is that when fitted correctly, the Burris Signature rings are said to have 200% more gripping strength then a standard ring. As such that front rings just simply grips the hell out of the scope body and does not let go!!
At least not nearly as easily as a conventional ring.
If you want even more stability, go with a double dovetail base with a set of signature ring or a weaver style base with a set of Z-rings.
These systems are what I recommend as minimum for the type of rifle you will be using. I have yet to see a properly fitted set of Burris signature rings fail to hold a scope securely. Only one I did see fail was on a rifle where the left windage screw literally broke in half from being over tightened.
The key here is degreasing everything on the base and ring system except the dovetail contact surfaces where a quality moly grease should be used.
Everything else should be oil free and dry.
Above this you can get into the tactical style rings and bases and they certainly have the gripping strength to easily cover your needs.
Remember Alot of the stress on the scope is a result of the weight of the scope itself and the height above the axis of the bore at which it is mounted. The heavier the scope, the more serious a base and ring you need to keep it still. Also, the higher it is mounted, the more stress the scope endures under recoil and the effects of the brake under recoil.
Allen Precision Shooting
Home of the Allen Magnum, Allen Xpress and Allen Tactical Wildcats and the Painkiller Muzzle brakes.
I'm certainly getting an education with this one. Good posts fellas. [img]/ubbthreads/images/graemlins/grin.gif[/img]
ss7MM, Thanks for the post. Points are spot on and well taken. No the scope isn't ruined but I sure can't say "only slight" ring marks any longer on that one. [img]/ubbthreads/images/graemlins/blush.gif[/img]
The front schooched ahead nicely. The rear ring gouged a bit on the bottom. [img]/ubbthreads/images/graemlins/frown.gif[/img] But I doubt I'll ever get rid of it anyway. Who would want a used cabela's scope anyway.
Also Kirby seems to be spot on regarding the rear ring and windage screws. I was real careful to get them centered on both sides. That didn't last long. [img]/ubbthreads/images/graemlins/grin.gif[/img]
Kirby, I like the twin dove tail idea. Remember us talking building something that max weight is less than 16#. That's still on my burner, which is y I'm messing with the 250 gr bullets and muzzle brake. Besides being fun I'm getting the feel for the larger caliburs.
The 338 Win now sports a set of Burris Sigs. So far 9 full power shots and things look good.
Thanks again guys
I may be the slowest guy on the mountain . . . . but . . . . I'm on the mountain!