WVRJ
I love my Rem.700 , mine is a 308. Started out as the 700 LTR , after firing 4000+ through the barrel , turned it into a benchrest only , changed the stock , trigger , barrel and completely blueprinted. I tried the speed lock firing pin and spring , didn't care for it m. Use the nstandard spring and the standard weight spring. If I could constantly shoot that one hole 5 shot group the lock time may make a difference , I can shoot .5 groups at 200 yards but that's about the best this 74 year old can expect. .
The brass piece in the bolt body is a mystery, I also use a single stage , load 30 308 at a time , hand gun 50 at a time , never loaded volume. This empty case that caused my problem was all on me . My system on reloading is safe , l made a mistake in placing the case in the shell holder , without charging , I was distracted for a few seconds , placed the bullet on the case and seated . The scale let me know I was one round off . Instead of pulling all the loaded cases , maybe 30 , I weighed all and pulled the lightest charge , when that case was charged I thought is could have been because I zeroed the scale in the middle of my loading session and screwed up the count by one . Luckily it reared its head on the 5th shot , after clearing all other rounds fired fine . Will not happen again I can assure you. Good luck with your 700 , it's my one and only benchrest rifle , love the rifle , not even thinking of another. Changed the trigger to a Jewell made the biggest difference in my groups.
Chris
PS : the last 50 cases that were primed over 5 years ago , all fired well , or should I say exited the barrel , T G.