SPR mod 0, 5.56 caliber, 14.7" barrel 50 rounds through this gun, I purchased brand new. Details are here: https://www.lwrci.com/p-250-m6a2-spr.aspx#inf-tabs 16" overall length so it's legal, awesome gun, fully loaded from the factory! I've got a brand new Trijicon ACOG 01 available to go with this also. Any questions, feel free to ask but the LWRC site has all the details. $2299 for the rifle. If you want the ACOG with it, I'll do the package for $2950. No I will not sell the ACOG separate. Do your research, the package price is a steal. The gun is as new and the scope is new. I'm open to trades, pm offers.