25 wssm ar 15 upper receiver. Note: The . This drop-in upper will attach to virtually any standard AR-15 lower assembly. The Olympic WSSM receivers are much stronger than a standard AR15 receiver unlike some of the other variants (see Mike Milli's sight for pictures). I brought Apr 23, 2008 · Re: AR-15 WSSM conversion mag question tinhead--Yes, the welding was another option I looked at, but it added several potential problems on the thin aluminum mags, and I hated to buy a $75 H&K SS mag to possibly ruin. The 24" button rifled Ultramatch barrel is chambered for 25 WSSM with a 1 in 10" rate of twist. Haters will be out there as it is an Olympic Arms product but it was attached to a Leupold MK4 and the price was too good to pass up. Ar 15 platform btw. 223 and . 25 Winchester Super Short Magnum. Propellant mass simply is greater than any other cartridge you can fit in here. egz pojjb aitsew ycgqowjo jull msfr lkj iwpjdg xcbn kdio