Shoulder bumping question

[DaveTooley]

I would generally agree, except the case is pushed on the base with the cone in the center of the shoulder centering on the cone of the chamber….so, yea, looser will cause the round to sit lower in the chamber, won’t it. Causing the bullet to be off center?

Tell me how much lower it can be when the neck is not completely sized down to the shoulder. Freebore diameters are measured in tenth thousandths of an inch for most common cartridges.
A solution in search of a problem.

At the Shamrock last weekend I was shooting in the .3's @200 yds. That's really good for me since I don't shoot much these days. I haven't cleaned primer pockets in decades, never measure shoulder bump, and never clean the inside of the case neck. Oh and never anneal.

 

[grantre72]

I personally have no first hand experience to verify/present, but a friend with 9 Benchrest Hall-of-Fame points to his credit told me to shoot for .0005 bump, .001 bump. He also seats +.012 into the lands.

 

[6MMsteve]

I use One Shot so I do actually lube the shoulders but it's thin, if using any lube it's going to push lube up to shoulder area some in time, black goo on body shoulder intersect, seen this before I started cleaning my dies, which was all learned from this site the little things...keep those dies clean

 

[DShortt]

All I know is you guys are causing me to want to find a place that I can practice at 600 yards so I can put up or shut up.

Apparently that's the standard now days.

Excepting the bench rest shooters of course.

 

[Dave Way]

.0005” is probably impossible to truly accurately measure depending on the tool you’re using. I doubt that it would show even at 1,000 yards assuming top notch equipment.

Remove the firing pin assembly and ejector if present. If you feel pressure when closing the bolt on a sized case on some but no pressure at all on others, you are about to shoot some fliers.

If you are concerned about getting super consistent shoulder bumps, annealing is the answer along with consistent lubrication. Just my opinion.

Dave.

 

[J.d. Popkes]

.0005” is probably impossible to truly accurately measure depending on the tool you’re using. I doubt that it would show even at 1,000 yards assuming top notch equipment.

Remove the firing pin assembly and ejector if present. If you feel pressure when closing the bolt on a sized case on some but no pressure at all on others, you are about to shoot some fliers.

If you are concerned about getting super consistent shoulder bumps, annealing is the answer along with consistent lubrication. Just my opinion.

Dave.

And comp shell holders

 

[nksmfamjp]

Tell me how much lower it can be when the neck is not completely sized down to the shoulder. Freebore diameters are measured in tenth thousandths of an inch for most common cartridges.
A solution in search of a problem.

At the Shamrock last weekend I was shooting in the .3's @200 yds. That's really good for me since I don't shoot much these days. I haven't cleaned primer pockets in decades, never measure shoulder bump, and never clean the inside of the case neck. Oh and never anneal.

Well there you go….I’m no Dave Tooley. I’m just doing what seems to work through my testing. That said, my accuracy is ho hum of late.

 

[mikecr]

I could see how OP's culling on headspace idea could be beneficial.
If he dip annealed to upper bodies in preps, fully fire formed cases, FL sizes, and then notices some bump departing from the rest down the road.

Cases have character. A batch springs back with variances. They resist the pressure peak with variances.
Maybe not with the tiny 6PPC at competitive loads, but with hunting capacity cartridges running lower pressures.

He might frequently deep body dip anneal to combat it, but I'd just toss offending cases.
They're just different.
When I'm group shooting and I have a flier I store the flier case differently.
If prior & further grouping is ok, I pluck that case and toss it.