Sunday, at the range where I am a part time range officer, I was helping a new shooter with his "sniper rifle" It was a Remmy 700 chambered in 300 Win Mag. medium heavy barrel in an expensive aluminum frame / stock with a suppressor.
Using a bipod, he was getting erratic groups of about 4" at 100 yds.
A fellow range officer, an experienced F class competitor fired the rifle with similar results, very poor grouping. His ammo was of good quality, not match grade but good hunting grade, probably good for 1" at least @100 yds.
I was watching him and his rifle very carefully to learn what the problem was when I noticed that the barrel / suppressor was violently vibrating up & down about an inch & a half with each shot, diminishing quickly in perhaps 1/4 second. YES, clearly visibly shaking up & down with each shot. Action screws were tight, barrel was free floated. We removed the can & then he proceeded to put three rounds through the same hole @ 100 yds with no visible vibration.
It appears that the weight of the can (about 2 1/2 lbs, it was a steel can) gave the barrel the wrong weight & resulted in the harmonic shaking we observed. The can was attached to the barrel with a quick release screw on type mount & felt to be tight.
Learn something new every day, and this was really something new. I have seen high speed photography of rifle barrels vibrating, but never anything close to this.
Using a bipod, he was getting erratic groups of about 4" at 100 yds.
A fellow range officer, an experienced F class competitor fired the rifle with similar results, very poor grouping. His ammo was of good quality, not match grade but good hunting grade, probably good for 1" at least @100 yds.
I was watching him and his rifle very carefully to learn what the problem was when I noticed that the barrel / suppressor was violently vibrating up & down about an inch & a half with each shot, diminishing quickly in perhaps 1/4 second. YES, clearly visibly shaking up & down with each shot. Action screws were tight, barrel was free floated. We removed the can & then he proceeded to put three rounds through the same hole @ 100 yds with no visible vibration.
It appears that the weight of the can (about 2 1/2 lbs, it was a steel can) gave the barrel the wrong weight & resulted in the harmonic shaking we observed. The can was attached to the barrel with a quick release screw on type mount & felt to be tight.
Learn something new every day, and this was really something new. I have seen high speed photography of rifle barrels vibrating, but never anything close to this.