Case sizing issue

[Pareto]

I have a small puzzle with my reloading brass. I have about 120 2x fired Lapua 6 br brass and I check the cases with a Wilson case gauge. I resize with a full length Wilson die and most of the brass is fine and fits the case gauge perfectly.

However, I have about 8 or 9 cases that seem a bit odd. The case head sticks out a bit more from the case gauge than the others. Not a lot, and it might make no difference in the gun but it still is odd. I bumped the shoulders about 0.003 like all the other cases and I was unsure about these 8 pieces so I reran them through the sizing die and as far as I can measure, it seems the shoulder was bumped back the same as the rest of the 120 and I trimmed the brass to virtually identical lengths. Yet these 8 behave as if the shoulders weren't bumped back far enough. What is going on? Should I just bump the shoulders back a bit more so that the cases fit the gauge as perfectly as the others?

 

[6MMsteve]

run them in the die and let dwell for 10 seconds, then remeasure

 

[C.E.Smith043]

Could also be a difference in thickness of the brass at the case head???

 

[TTE]

What do the 8 measure vs. the others ?

Are the cases annealed ?

As mentioned above ..... let them sleep in the die for awhile.

 

[Straightshooter1]

I have a small puzzle with my reloading brass. I have about 120 2x fired Lapua 6 br brass and I check the cases with a Wilson case gauge. I resize with a full length Wilson die and most of the brass is fine and fits the case gauge perfectly.

However, I have about 8 or 9 cases that seem a bit odd. The case head sticks out a bit more from the case gauge than the others. Not a lot, and it might make no difference in the gun but it still is odd. I bumped the shoulders about 0.003 like all the other cases and I was unsure about these 8 pieces so I reran them through the sizing die and as far as I can measure, it seems the shoulder was bumped back the same as the rest of the 120 and I trimmed the brass to virtually identical lengths. Yet these 8 behave as if the shoulders weren't bumped back far enough. What is going on? Should I just bump the shoulders back a bit more so that the cases fit the gauge as perfectly as the others?

No, don't change the die to bump the shoulder more. As mentioned, there may be a difference the the case thickness where you're not getting as much sizing done on them. Increase the dwell time (amount of time the case sits in the die before pulling the case out), like the 10 seconds also suggested.

The way I size my cases these days, I always have a dwell time that 4-5 seconds and I get very consistent results. And I must admit too, I also anneal my cases after every firing, which also helps, particularly for consistent shoulder bumps.

 

[Fast14riot]

Differences in diameter and angles can also affect fitting in a case gauge. However, the only case gauge that really matters is your chamber. Mark those cases and shoot them to see if there are any differences on target. If so, they get culled and relegated to foulers.

 

[243winxb]

these 8 behave as if the shoulders weren't bumped back far enough.

Shoulder bump- A Headspace Comparator will give a more accurate measurement, then a case gauge.

2 firings may not fully expand brass to the chamber. More so with starting loads.
The 8 brass may have expanded fully to the chamber.

Adjust fl die so the 8 brass chamber correctly. The rest will soon or later expand.

 

[mgunderson]

I have the slotted the back of a case gage to allow more repeatable measurement with a caliper.

Likely the case is hardening up and possibly you might have been sizing the brass too much up to this point.

Do the 8 cases fit in the chamber or do they feel tight?

 

[LHSmith]

Shoulder bump- A Headspace Comparator will give a more accurate measurement, then a case gauge.

2 firings may not fully expand brass to the chamber. More so with starting loads.
The 8 brass may have expanded fully to the chamber.

Adjust fl die so the 8 brass chamber correctly. The rest will soon or later expand.

I agree. Just remember to return the die setting back to where you started. FWIW I never found "dwell" time in the die to have any effect - after loading 1000's of SRBR competition rounds.

 

[rwj]

Until one knows what part(s) of the case are contacting the gauge/chamber, definitive corrective actions can not be determined. An easy way to identify the restrictive surfaces is to apply a transfer fluid to either the gauge or case then insert/inspect.

 

[L.Sherm]

Yet these 8 behave as if the shoulders weren't bumped back far enough.

What is the behavior? Resistance on the bolt closing? If thats the case and your sure of the bump then check the base of the cases they could be not sizing correctly there and thats were the Resistance is coming from.

 

[K22]

The Wilson case gauge (old version) is a qualitative tool, not quantitative. There is about .005" between the upper and lower steps. Furthermore, it only works for SAMMI spec chambers, but even so, it is a qualitative tool.

Use a bump gauge and caliper to obtain precise baseline measurements of case head space before sizing (primer removed) and after sizing.

.003" is a lot of bump for a bolt rifle. I have never had to bump cases that much for any bolt rifle. As someone else noted, the rifle chamber is the ultimate case gauge, but once adequate sizing (die setting) is verified with the rifle chamber, the bump gauge provides an efficient method to monitor sizing adequacy.

In my experience, some variation in sizing measurements often occurs due to allowing for cases to fully fire form to the rifle chamber, operator measurement inconsistency, caliper repeatability, differential metallurgy in the brass, and age hardening (if you don't anneal). None of these issues have created difficulty for me in sizing cases once I have established the optimum sizing verified against the rifle chamber. From time to time, I have to change the sizing amount which I accomplish quite easily with Skim Shims under the lock ring of the F/L die.

Bottom line: You should only be sizing your case enough to allow for adequate chambering of case in your rifle chamber. Often a zero to .001" bump is enough in my experience for most bolt rifles.

 

[Bill K]

Try a small base die on those odd ball cases and see if they don't drop in then.

 

[K22]

However, I have about 8 or 9 cases that seem a bit odd. The case head sticks out a bit more from the case gauge than the others. Not a lot, and it might make no difference in the gun but it still is odd.

This may not be a case head space issue. Check to see if there is a slight bulge in front of the case head.

If there is, this could be due to the chamber being slightly out of round or an anomaly in the case. Trying to "fix" this by increasing the bump or using a small base die will result it over sizing the case. Sierra published an article on this a few years ago.

If the affected cases chamber properly in the rifle, then there is no need to "fix" this.

PS: I have a 223 Rem bolt rifle that shoots terrific but has this condition. A few cases, not all, exhibit this slight budging which will resist fully seating in a Wilson Case Gauge. However, the affected case shoot on par with the others and chamber without issue.

 

[Pareto]

I'll check out all of these things later this weekend.

 

[JFrank]

I have a small puzzle with my reloading brass. I have about 120 2x fired Lapua 6 br brass and I check the cases with a Wilson case gauge. I resize with a full length Wilson die and most of the brass is fine and fits the case gauge perfectly.

However, I have about 8 or 9 cases that seem a bit odd. The case head sticks out a bit more from the case gauge than the others. Not a lot, and it might make no difference in the gun but it still is odd. I bumped the shoulders about 0.003 like all the other cases and I was unsure about these 8 pieces so I reran them through the sizing die and as far as I can measure, it seems the shoulder was bumped back the same as the rest of the 120 and I trimmed the brass to virtually identical lengths. Yet these 8 behave as if the shoulders weren't bumped back far enough. What is going on? Should I just bump the shoulders back a bit more so that the cases fit the gauge as perfectly as the others?

I’ve experienced the same symptoms as you have using the Wilson case gage, the neck shoulder junction is likely the area of contact.

 

[NZ_Fclass]

I have never found the need to bump a BR case. I did have a BR at one time that was 6 thou out of spec, long, that is. A case gauge would have shown that out of spec - but, of course, it still sheo really well.

I suggest that you get a comparator - and a decent vernier. I started out with a Chinese one, but soon, when having problems with consistent case measurement, bought a Mutitoyo. Measure a case that is "on spec". then zero the device - all other cases will show plus or minus to the spec case. Much quicker and more reliable than getting the 4 digit number for each.

 

[Coyotefurharvester]

How does a fired, deprimed but NOT sized case fit in the case gage? That is your starting measurement. It may or may not be above the top step? Does the case chamber properly that doesn't fit the Wilson gage after sizing? Are you using the expander button when setting up the die, removing any lube from the case shoulder before checking in the gage?

 

[Doom]

Fired resized cases sometimes have slight rim expansion or burrs that catch on the top edge of the gauge recess. I have a 223 gauge that does this quite often, especially with 5.56 cases. It doesn't affect the chambering of the case in rifle.

 

[memilanuk]

I've ran into this in two instances.

One was some LC 5.56 brass that no matter how much I bumped the shoulder some rounds wouldn't go fully into battery (AR Service Rifle). Measured all sorts of things, but only found it using a Wilson case gauge. The suspect cases had bunged up rims (1x fired mil surp) that kept them from chambering fully. After that, I started gaging every piece of brass before taking it to a match - didn't want to find the next one the hard way!

The other... was very recent. I have various headspace comparators, but had recently picked up a Wilson case gauge micrometer. On my 308 Win, it worked great! But then I went to use it with some 223 brass from one of my FTR bolt guns... and the cases wouldn't go into the gauge. I used my regular comparators to verify the headspace bump, but it was driving me nuts.

Then I found this:




And there's a matching ding exactly 180° out on the other side.

Apparently, somehow, some when, I must have had a shell holder that was just a *tad* too tight. Any who, it left just enough of a nick to keep the case from seating into the gauge

Just figured I'd throw it out there.