FL sizing shortens OAL by .005 + ????

[thefitter]

I just FL sized some .308 brass that had been fired quite a few times with only neck sizing between firings. I needed to bump the shoulder .002 and decided to run it through the FL die. I'm very surprised to see that it shortened the OAL by .005.

 

[DCRYDER]

Are you sure you're only bumping shoulder .002"???

Cause the neck bone's connected to the shoulder bone. ;D

 

[bigedp51]

Measure your cases and then use one of the methods below to prevent over sizing. Most "standard" sizing dies will resize the case at least .002 below minimum headspace.

;D

 

[BoydAllen]

If you have any of those cases, that have not been FL sized yet, knock the primer out of one, measure its OAL and using a caliper attachment, "headspace", and then size it, and repeat the measurements. Tell us what you get.

 

[thefitter]

Are you sure you're only bumping shoulder .002"???

Cause the neck bone's connected to the shoulder bone. ;D

Yep .002

 

[thefitter]

If you have any of those cases, that have not been FL sized yet, knock the primer out of one, measure its OAL and using a caliper attachment, "headspace", and then size it, and repeat the measurements. Tell us what you get.

OK I have some from the same batch, I'll try that tomorrow.

 

[alf]

X die?

 

[thefitter]

X die?

Forster FL

 

[artbosco]

I just FL sized some .308 brass that had been fired quite a few times with only neck sizing between firings. I needed to bump the shoulder .002 and decided to run it through the FL die. I'm very surprised to see that it shortened the OAL by .005.

When was the last time you calibrated your measuring tool?

Do you have a Mitutoyo .050" rectangular gage block that you can employ for this purpose?

If not, here's what one looks like, and four sources: http://www.google.com/products/catalog?q=mitutoyo+.050%22+gage+block&oe=utf-8&rls=org.mozilla:en-USfficial&client=firefox-a&um=1&ie=UTF-8&cid=161231763864581905&ei=0AxUTYGVDoH7lweDzYjgCg&sa=X&oi=product_catalog_result&ct=result&resnum=11&ved=0CHIQ8wIwCg#

 

[thefitter]

I just FL sized some .308 brass that had been fired quite a few times with only neck sizing between firings. I needed to bump the shoulder .002 and decided to run it through the FL die. I'm very surprised to see that it shortened the OAL by .005.

When was the last time you calibrated your measuring tool?




Do you have a Mitutoyo .050" rectangular gage block that you can employ for this purpose?

If not, here's what one looks like, and four sources: http://www.google.com/products/catalog?q=mitutoyo+.050%22+gage+block&oe=utf-8&rls=org.mozilla:en-USfficial&client=firefox-a&um=1&ie=UTF-8&cid=161231763864581905&ei=0AxUTYGVDoH7lweDzYjgCg&sa=X&oi=product_catalog_result&ct=result&resnum=11&ved=0CHIQ8wIwCg#

Never it's only 2 months old. It's a Mitutoyo 500-474, Digimatic Digital Solar Caliper, 0 - 6"/150mm, .0005"/0.01mm

How often do you need to calibrate?

 

[queen_stick]

Were the primers still in the case when you measured prior to the FL sizing? That burned me once, before I knew to look for it. I had some cratering on my fired primers that caused my initial measurements to stick out .005" +, just as you described. Then after the primers were punched out (decapped), my measurements were all over the place. After looking at the fired brass, I realized that the primers were sticking out of the pockets a few thousandths, and if they were cratered, they stuck out even further.

Bottom line... decap the brass before doing any measurements where the case head is a reference point.

Walt

 

[thefitter]

Were the primers still in the case when you measured prior to the FL sizing? That burned me once, before I knew to look for it. I had some cratering on my fired primers that caused my initial measurements to stick out .005" +, just as you described. Then after the primers were punched out (decapped), my measurements were all over the place. After looking at the fired brass, I realized that the primers were sticking out of the pockets a few thousandths, and if they were cratered, they stuck out even further.

Bottom line... decap the brass before doing any measurements where the case head is a reference point.

Walt

Everything was decapped and cleaned.

 

[artbosco]

I just FL sized some .308 brass that had been fired quite a few times with only neck sizing between firings. I needed to bump the shoulder .002 and decided to run it through the FL die. I'm very surprised to see that it shortened the OAL by .005.

When was the last time you calibrated your measuring tool?

Do you have a Mitutoyo .050" rectangular gage block that you can employ for this purpose?

If not, here's what one looks like, and four sources: http://www.google.com/products/catalog?q=mitutoyo+.050%22+gage+block&oe=utf-8&rls=org.mozilla:en-USfficial&client=firefox-a&um=1&ie=UTF-8&cid=161231763864581905&ei=0AxUTYGVDoH7lweDzYjgCg&sa=X&oi=product_catalog_result&ct=result&resnum=11&ved=0CHIQ8wIwCg#

Never it's only 2 months old. It's a Mitutoyo 500-474, Digimatic Digital Solar Caliper, 0 - 6"/150mm, .0005"/0.01mm

How often do you need to calibrate?

I compare the readout on my gauges, regardless of type, with the Mitutoyo .050" gage block, anytime I'm curious about the readings I'm getting or whenever they seem really distorted. 99% of the time my equipment agrees with the block.

To calibrate simply measure the .050" gage block with your calipers. Since you know the block measures .050" that's what your gauge should read. If it doesn't adjust the gauge [in this case your calipers] so that it reads .050". The adjustment you made is the "calibration". The block was your guide. If you don't have one I recommend you acquire one. There are all types, some going out to 6 places [.000000]. With more places the higher the price. Three is all you need. I chose Mitutoyo because they make good equipment and the $30-$40 price range was what I was willing to pay.

Another issue, when it comes to measuring, is the amount of pressure you apply to your calipers when measuring an object. It doesn't take much pressure to go from .002" to .005". I know I could never feel that slight amount of difference with my hands. I take many measurements to get a consensus or average.

Another question. When was the last time you trimmed your brass to the same length?

Try this. Trim 5 pieces. Chamfer and Deburr. Measure them. Record the measurement. Push the shoulder back the .002" you think you're moving it on those same 5 pieces. Remeasure them. Compare all 5 to the trimmed measurement. What's the difference? Whatever it is ... they should all be the same. Hopefully, only a .002" OAL difference.