Update...Small pressure sign, ok to keep loading????

[jpope02]

Could be a dirty or rough chamber or a head space problem or gunge build up on ejector or too hot a primer. Try to FL size brass with die set to just bump shoulder back after you inspect and clean chamber

 

[jpope02]

Could be a dirty or rough chamber or a head space problem or gunge build up on ejector or too hot a primer. Try to FL size brass with die set to just bump shoulder back .001" after you inspect and clean chamber. Go luck!

 

[jpope02]

Could be a dirty or rough chamber or a head space problem or gunge build up on ejector or too hot a primer. Try to FL size brass with die set to just bump shoulder back .001" after you inspect and clean chamber. Go luck!

 

[JimmyCP]

I have been shooting a new build for a few months (6.5-284 Defiance action with proof barrel) and have really struggled to find a load with low ES. After several attempts I ran a ladder that showed 53.4 to 53.6 of H4831SC was single digits for ES and shoots 1/2 MOA out to 500 yards. Problem is that with fire formed brass I get a hard bolt lift (last 10 degrees), not real hard but there is some pressure there. I know if I drop to 53.2 it will go away but the ES goes to 20 plus. Deer season is just around the corner and I would like to stick with this load (53.4) and maybe try something different in the off season. So the questions is, is this a horrible idea? Will it damage my Defiance action? Any thoughts from you more experienced gentlemen would be appreciated!!!

9/11 After some thought I realized that the hard bolt issue at 2950 fps seemed new. I have loaded several hundred rounds (ladder testing and fire forming brass) with some loads running over 3000 fps and never had a heavy bolt issue (did have some primers start to crater). I then realized I had changed my brass prep a few weeks ago and started wiping each case below the shoulder with Lyman case lube prior to full length sizing. I would wipe the brass off with a paper towel after sizing but never really cleaned the case. Today as a test I cleaned the rifle chamber and several rounds with de-greaser and went to the range. No heavy bolt lift!!!! So crazy how the small things can cause problems

Thanks for all the thoughtful ideas and info, I will do some more shooting this weekend and give updates if something changes.

Thanks Jeff

I had the same issue with 4831sc. One issue was the hornady brass. After I went to better brass I could barely hit 2900 and flat primers and hard bolt lifts.
One 6.5 x284 140grn likes retumbo 57.5 grn, wrlm primer, .002 neck tension. 10 shots 8fps dev. And .25 moa on average.

But since you've shot this round and its new issue could be a number of things.
If your original brass was trimmed shorter you could have some carbon build up in the throat of your chamber. Other issue could be carbon or copper build up just off the lands. Other issue is crap built up in your lugs.

That's what I have experienced on others guns that have been brought to me to figure out. Just cleaned one for four hours after he just spent 2 hours cleaning it. He never heard of copper solvent.
I polished the bore and barrel after I got all the crap out, then the chamber and cleaned the lug pockets. No more issues.
I clean mine before every hunt, foul it with 20 shots and shoot through the chrono make sure everything is right.

I would make sure the guns clean before you mess wth a load you know works.

 

[JimmyCP]

That's what I got out after he claimed he cleaned it for 2 hours