125 gr SWC not plunking

[painter]

It doesn't measure to the ten thousandth.  That fourth number is either a 5 or a 0, so it measures to the the 2000th, and since calipers aren't particularly precise, I'd call it .356.

Either way, you'd be best off not to use an FCD with lead or coated lead.

I'd disagree with your interpretation of the caliper reading. It is indeed 10 thousandths...just sayin' The fact that the number comes from calipers makes it irrelevant. .356 it is.

[IDescribe]

It doesn't measure to the ten thousandth.  That fourth number is either a 5 or a 0, so it measures to the the 2000th, and since calipers aren't particularly precise, I'd call it .356.

Either way, you'd be best off not to use an FCD with lead or coated lead.

I'd disagree with your interpretation of the caliper reading. It is indeed 10 thousandths...just sayin' The fact that the number comes from calipers makes it irrelevant. .356 it is.

Kindly explain further, sir.   😀

My interpretation is that the 5 in the ten thousandths spot indicates only that it's somewhere in the middle between two separate thousandths.   So .3565 (best case) indicates that it's somewhere maybe .35625-.35675.  And then .3570 indicates somewhere .35675-35725.  To be clear, I think that's the most that. 0005 indicates - - I know better than to think it's that precise.

Anyway, if all the measurement indicates is that's it's somewhere kinda sorta half way between two separate thousandths, that seems like a resolution of 1/2000, no?

Is this a difference of interpretation?  Or am I just flat out wrong for not having been schooled properly in the languages of measurements? 

[painter]

It doesn't measure to the ten thousandth.  That fourth number is either a 5 or a 0, so it measures to the the 2000th, and since calipers aren't particularly precise, I'd call it .356.

Either way, you'd be best off not to use an FCD with lead or coated lead.

I'd disagree with your interpretation of the caliper reading. It is indeed 10 thousandths...just sayin' The fact that the number comes from calipers makes it irrelevant. .356 it is.

Kindly explain further, sir.   😀

My interpretation is that the 5 in the ten thousandths spot indicates only that it's somewhere in the middle between two separate thousandths.   So .3565 (best case) indicates that it's somewhere maybe .35625-.35675.  And then .3570 indicates somewhere .35675-35725.  To be clear, I think that's the most that. 0005 indicates - - I know better than to think it's that precise.

Anyway, if all the measurement indicates is that's it's somewhere kinda sorta half way between two separate thousandths, that seems like a resolution of 1/2000, no?

Is this a difference of interpretation?  Or am I just flat out wrong for not having been schooled properly in the languages of measurements? 

Four places is the ten thousandths place. It's just math. If the calipers were accurate enough they might display a 1, a 3, or a 7. Fact is they round off, so the best you can get is a 5 because it's 356+. A micrometer will give the exact number, and if they're capable of reading to 4 places...it's in tens of thousandths.

[IDescribe]

Gotcha.

At least we're in agreement that he should drop that ten thousandth with calipers. 

[1SOW]

To measure the relevant part of the bullet, you need to pull the bullet.

But yes,. 356 ID is too narrow for a. 357 bullet. Seriously, just buy a regular taper crimp die.

Yes!  Don't SQUISH your bullet .  A bullet is an aerodynamic body spinning at high rate of speed.  If you change the shape,  you change the flight path's  karma with the point of aim. . ??🔫

[IDescribe]

In addition that, you change bullet to barrel fit.  It's just all around bad.

[Wobbly]

Us "pro" reloaders have a technical term we use  to accurately describe this bullet distorting phenomena, and said loss of accuracy...

It's called "Bad Boogie".

 

[charlus]

So, I shot 30 test rounds yesterday loaded through the auto loader (4.0 gn +/- 0.1 gn.  Weight hand checked every 5 loads ). Very accurate. No leading of the barrel outside normal fouling. No incident. Light recoil. I'll check the speed when I go to my outdoor range way West from here.

To document the discussion about size, measurements, Lee FC dies and remove caliper accuracy problems, I've taken a micrometer (checked its accuracy against feeler gauges) and here are my findings:
MBC 9mm SWC are exactly 0.3565" (+/- 0.00005 all around)

When run through FCD and pulled out, the bullet is still 0.3565 though fitting tight in the case

and the case mouth diameter is 0.3791 (+/- 0.0005 all around) which matches the 0.113" (0.28mm) wall thickness + bullet diameter.


I think this load data is good and reliable for that weapon/case/bullet/powder/OAL.
It allows the use of SWC in the CZ S2 which is a nice improvement for target practice.
If anyone has the opportunity to test it, return findings and offer opinion, that'd be nice.
Cheers
 

[dragon813gt]

Don't use the FCD with lead or coated lead. You'll sewage the bullet and reduce accuracy, if not induce tumbling.

This isn?t always the case.  The issue w/ the FCD is the carbide ring diameters vary.  Some will swage bullets down while others won?t touch the case at all.  The issue is the ones where the diameter is to small.  And technically it?s not to small because the dies are designed for jacketed bullets.  People blame the FCD for all sorts of problems when it comes to cast bullets.  It?s not always the cause of the problems.

[Wobbly]

So, I shot 30 test rounds yesterday loaded through the auto loader (4.0 gn +/- 0.1 gn.  Weight hand checked every 5 loads.

You really need to stop that practice !

If you are unsure of what your powder measure is doing, then fill the PM with powder and dump powder into a case over and over. Weigh each dump and record it in Excel. That way Excel can plot the results for you.



During loading, a simple look into each case is enough to verify what you need to know. If you continue to stop in mid-process to make "safety checks" the exact opposite will happen. Stopping actually causes more problems than it locates. Problems like squib loads.

I think this load data is good and reliable for that weapon/case/bullet/powder/OAL. It allows the use of SWC in the CZ S2 which is a nice improvement for target practice. If anyone has the opportunity to test it, return findings and offer opinion, that'd be nice.

Oh, we'd love to, but there's just one problem. You didn't tell us what "this load" is.

[charlus]

I always check the load every five rounds when I start using a new powder to make sure it stays consistent : 4.0gn +/- 0.1.
P.M have their temperament sometimes when you change their habits.
When loading I ,of course, make a visual check of each loaded case to verify the level but it's only a safety check, not an accuracy check.
The full data was given on page 5 of this post. Here is the copy:

CZ S2 with OEM #15 recoil spring, light CGW hammer, firing pin & trigger springs. CGW adjustable sear. CZC hammer.
Trigger pull 1100 grams (38.8 oz)
Brass from Starline, Winchester SP primer, Powder RS Silhouette, Bullet: Missouri 125 gn SWC set at 27.8mm OAL
Each load hand weighted.
The published starting load for the 125 gn lead RN for that powder is 4.5 gn (Nothing published for the SWC)

[Wobbly]

I always check the load every five rounds when I start using a new powder to make sure it stays consistent : 4.0gn +/- 0.1.

PM have their temperament sometimes when you change their habits. When loading I, of course, make a visual check of each loaded case to verify the level but it's only a safety check, not an accuracy check.

Again, in a teaching spirit I disagree. A PM is a mechanism that should be able to have consistent output. If you'll think about it, consistent output is the entire job of ANY machine. And a PM is definitely a machine.

? PM accuracy verification should be carried out BEFORE reloading starts, so that you don't need to stop.

? If a PM is known NOT to be consistent, then there's the obvious...
- Allowing 80% of product to pass un-inspected is not a good Quality Program
- If static has been treated and a powder baffle is present, then the next thing is inconsistent operation by the user
- If all sources of error have been studied and the PM is still inconsistent, then it needs to be replaced

The full data was given on page 5 of this post. Here is the copy:

We drew up the Load Templates listed in the Stickies exactly for this reason: to get all the pertinent data in one place. To help US help YOU.

When you make it easy for people to help you, then lots of people will. When you make people wade through 6 pages of thread to find all the data to help you, then...

I'm just sayin'   

[IDescribe]

I always check the load every five rounds when I start using a new powder to make sure it stays consistent

Stop doing this.  Testing the consistency of the powder measure can be done outside of bullet production.

Making rounds while testing consistency of the powder measure doesn't change the consistency of the powder measure. It only increases the odds of your making a mistake. The ONLY way to make sure every bullet is as close to the same as the next is to do the same thing with every bullet.

There are hundreds of tips and "best practices" published by experts, and stopping the process and doing somethjng different every fifth round is not one of them.