I have a question for the more experienced techs and airsmiths out there. Im doing some tech work on a Classic Army M15a4 Seal and am currently working on the "upper" gearbox. I know that this gun had been to a tech with its previous owner and appears to have an aluminum aftermarket cylinder head in it. Im going to install a Systema M100 spring, Angel Custom Ported SS Cylinder, Matrix High Speed Piston, ASG Ultimate Silent Piston head, and a Brass Silent Cylinder Head. I was wondering if anyone, maybe Uller, had any experiance using both aluminum and brass cylinder heads and if brass dampened the blow and vibrations better than aluminum or stainless? I do plan to use a Sorbo pad as soon as i can get my parts in ill measure the needed thickness. Basically im looking for opinions and facts on the physics of brass vs aluminum vs stainless steel for cylinder heads and cylinders.