Case head separation

[Edd]

In that Wheeler video, the shoulder was pushed back .0035".

 

[Bill Norris]

Bill,
They make other brass than Lapua???
Wayne

Not really. LOL.

 

[AICS308]

In that Wheeler video, the shoulder was pushed back .0035".

If my subtraction is correct the result is .002. Please correct me if I’m wrong.

 

[Edd]

If my subtraction is correct the result is .002. Please correct me if I’m wrong.

The starting measurement shows 1.1815 and the ending measurement shows 1.178. My calculator thinks the difference is .0035.

 

[AICS308]

The starting measurement shows 1.1815 and the ending measurement shows 1.178. My calculator thinks the difference is .0035.

You are correct looking at total bump. I use his method looking for .002 clearance between bolt face and base and not total bump. My confusion.

 

[Dolomite]

Some people like that snug fit and some like a loose fit when closing the bolt handle. There probably good arguments for one or the other. I've been using .002-.003 and haven't had issues with the exception that I get clickers every so often. Ring die has been my friend

 

[ELR LVR]

I bump .002" every time. Over 20 reloads on each case. No sign of case head separation. Must be a clearance problem somewhere else. Been reloading since 1970. Never had a problem. I don't think I am doing anything special.

Good to know on that measurement
I bump .001" I just rechecked some brass that Ive been using since 1999
I think I paid $60 /100 for that brass
Just now starting to get case head seperations
(I guess it can't last forvever lol, I tried)

 

[Tom S]

Mo,
I’m not sure if you mentioned if the primer pockets got loose before noticing the case head separating, but that is also a sign of over pressure. Although this load doesn’t sound too hot something you may want to check it out.

I do this by measuring immediately above the extractor grove with a ball micrometer before firing the case, then measure after firing comparing the two measurements. If the case head grows more than .00005 you are over pressure and should reduce your charge.

Most likely your pressure is fine, and the cause is from excessive shoulder bump. Just my 2 cents.

 

[bozo699]

Mo,
I’m not sure if you mentioned if the primer pockets got loose before noticing the case head separating, but that is also a sign of over pressure. Although this load doesn’t sound too hot something you may want to check it out.

I do this by measuring immediately above the extractor grove with a ball micrometer before firing the case, then measure after firing comparing the two measurements. If the case head grows more than .00005 you are over pressure and should reduce your charge.

Most likely your pressure is fine, and the cause is from excessive shoulder bump. Just my 2 cents.

What are you using to measure to .00005? And how do you hold that tolerance?
Wayne

 

[Tom S]

What are you using to measure to .00005? And how do you hold that tolerance?
Wayne

Although I’m not as good as my dad reading it, but I use a 1” tenth micrometer.

 

[Tom S]

What are you using to measure to .00005? And how do you hold that tolerance?
Wayne

.0005 sorry extra zero on my post. lol another cup of coffee needed

 

[bozo699]

.0005 sorry extra zero on my post. lol another cup of coffee needed

Now that sounds much better and the correct way to test for pressure!… not many know this or use it.
Wayne

 

[Tom S]

Now that sounds much better and the correct way to test for pressure!… not many know this or use it.
Wayne

My dad told me this many years ago, I just started measuring this way maybe a year or so, but so far, dam it seems to be holding true…go figure “the old man was right “.

 

[Rat Rifle]

.0005 sorry extra zero on my post. lol another cup of coffee needed

If this is true, then none of us should be reloading. There should be no such thing as a small base die. We should all trash our brass after the first firing.

OK, LETS HEAR IT

 

[bozo699]

If this is true, then none of us should be reloading. There should be no such thing as a small base die. We should all trash our brass after the first firing.

OK, LETS HEAR IT

He already said he added a extra zero accidently
Wayne

 

[Rat Rifle]

He already said he added a extra zero accidently
Wayne

I understand that.

 

[bozo699]

I understand that.

A half thou .0005 is the max expansion you want to see.
Wayne

 

[Rat Rifle]

A half thou .0005 is the max expansion you want to see.
Wayne

Then what is the purpose of a small base die ?

 

[bozo699]

Then what is the purpose of a small base die ?

To size at the .200 line
Wayne

 

[bozo699]

To measure for pressure your measuring at the web just ahead of the extractor groove. Even a small base die doesn’t size that far.
Wayne