headspace-is this possible?

[Axis II]

I took several members advice about using a bushing to measure headspace. I would measure a fired case and then zero the calipers using the bushing and case and set the die up for .2-.3 of a shoulder bump and it seemed to be working well.

Now...I Loaded up 20rds of my best load and headed to the range. First 5 were horrible but I haven't shot a rifle since October 2016. My next 5 shot very well and the next 10 opened up a lot. These loads used to be 5 shots all touching almost same hole as the first shot. Tonight they would be about 1-2inch groups.

Is it possible that messing with my dies from sizing to where the fired case would chamber to actually measuring to the datum is giving me my funky groups or could it be I'm a little rusty? out of 20rrds 5 were very impressive, 5 very good and 10 horrible.

 

[Snyper]

set the die up for .2-.3 of a shoulder bump

That should be a "bump" of .002-.003 and not 0.2 to 0.3

Go back to what was working for you before you tried to fix what wasn't broken.

 

[zb338]

If I were you, I would neck size some of the cases and shoot that way. Make sure the cases have been fired
in your rifle first. If you neck size only you SHOULD get good accuracy. Just remember though, nothing is
written in stone.

Zeke

 

[Axis II]

That should be a "bump" of .002-.003 and not 0.2 to 0.3

Go back to what was working for you before you tried to fix what wasn't broken.

yeah you are right its been a long day I forgot a zero. I was just trying not to overwork my brass as much and try and get some better accuracy. I'm telling you this ragged hole shooting is addicting and makes a man do stupid things like mess with dies that were already fine.

 

[Laphroaig]

Better is the enemy of good.

 

[JimKirk]

If you are using a bolt action rifle ... Simply size the bras until the bolt closes with a very light drag as it is closing ..... That way the case "fits" the chamber correctly.....

 

[2bfree]

If you are using the same load, the weather is the same, same rifle, and you are not going through withdrawal, It can only be an act of God.