Check the listing for details. Ruger Mark IV (4) 22/45 Bolt Truing Headspace Target Shooting Gunsmithing. Condition: New. Listed at 39.00 USD. This listing is for me Truing and adjusting your bolt on your Ruger Mark I, II, III, IV and 22/45 Models. I adjust the head space on the bolt to Sammi Minimum this keeps your groups tighter and trues the bolt so it sits flush against the breech side of your barrel. I have been Gunsmithing for the past 30+ years and I am a Tool and Die Maker by trade. Turn around time is 3-5 Days upon receipt if needing multiplies done no problem I will combine shipping, I also offer this service on 10/22 bolts LR and Magnum or any clones of them. Turn around time is same for 10/22 as well. I offer Shotgun machining on here as well take a fixed choke barrel and machine for screw in choke system to make your shotgun more versatile. Thanks for looking Happy Safe Shooting and May God Bless!!!!