Rifle Barrel Harmonics Mitigation


Jan 16, 2010
Hi All,
I have searched the forums and thought it was on this site that I saw a rubber device that slips over the barrel of a rifle and by sliding the device on the barrel, one can mitigate barrel harmonics to get a better shot group for most "store ammunition.

Does anyone know what that device is called?

Wow incredible fast response!!

That is it and thank you very much. I am going to do some research on it and if it is worthy of a purchase, I will report back on this thread, the performance on a 338 Win Mag with Factory ammo.

I've seen them in person, but never actually seen one used or heard of anyone using one. I'd be interested in any feedback that anyone has - just because I'm curious.
I tested one on my 300 wm. I came to the conclusion that on reloaded 180gr and up did not make any differ. On the other hand i found that shooting the real light bullets 150gr it did tighten up the groups quite a bit with factory ammo. I did not try factory heavy ammo so it may well work with them too. If you are going to reload i would not recommend it, just tune your load.
I use the SIMMS on all my rifles, and have found that they help bring that last "little bit" of accuracy. I agree that tuning the load to the rifle helps also, but the de resonator does the rest. Takes a little experimenting to find the sweet spot, on .300RUM the ring likes to be up close to the stock, the Hvy bbl .223 and 22-250 like it about an inch further out, and .243 ai wants it about 3" frome fore end. None of my rifles like the "donut" out by the muzzle.
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