Put together a 6mm Dasher on a LRVP 12 .Test fired 2 empty cases with primers, worked ok. Took it out to break in barrel, and could not get shells to fire,(handloads, 32gr Varget, 108gr Sierra MK at lands). Did get 2 to go off by recocking bolt, but some would not fire at all. Original gun was 204, changed out bolt head to .473 for 6br case size. Primers are .003 deep. Firing pin protrusion is .050. Installed a PTG bolt lift kit per instructions, went good. Now, I did headspace by using a new unfired case, and for no go used 2 layers scotch tape which gives .003-.004 and bolt wouldn't start to close. Have done 3-4 others that way, and had no problems at all. Used a Hornady bullet comparator (30 caliber) to check case stretch, and noticed case grew .005 on the shoulder. These are new cases, New bbl so don't know if this is "normal" or excessive. Any suggestions or advice is appreciated...Thanks, rsbhunter