I recently got a QSM for .223 Bushmaster. I do not have another suppressor to compare it to, nor have I seen/heard any suppressors owned by others. So my info is just before and after with this one can. The results: I can hardly tell any noise reduction at all, even with Extreme Shock subsonic ammo. The suppressor does increase backpressure in the rifle; my first few rounds I had smoke coming out of every hole in the receiver and the top 2 or 3 rounds in the magazine were powder coated in crud. I figure this is the fast track to fouling the works.
At any rate, for $1100 including transfer stamp, I sure expected way fewer decibels. Save your money or try a different brand. Also, the QSM can design appears to be just 3 baffles (4 chambers) with no steel wool or other media to dampen the noise; maybe look for one with more chambers and/or with other noise reduction features.
Hope this helps.
Yes, I am a vendor for QSM and own 2 of them myself. These are my favorite .22 cal suppressors I own. Small and light weight, Ti construction, I can use the same can on .22LR, 5.7mm FN, .223, .220 Ruger, 22-250, and full auto rated for M16. These are the most versatile cans I own.
The US Army testing of 5,56mm cans showed the QSM and the best performing for size and weight.
Read the QSM website.