Resizing Die Opinions

[T-shooter]

I took several Lapua .308 fired cases and picked one that is consistent with the others. Then measured using a .0005" readout caliper in 6 places before and after resizing. I set the Forster B/R F/L die for .001" shoulder setback to be sure I was contacting the case. Only the upper half of the case body is getting resized. .0015" at the top which is more than I would like to see. I know the neck expands a lot (stock Savage chamber) so cases get annealed every couple firings. The necks are turned to .014" thickness and the center of the neck runout on this one after F/L resizing is about .0007". The neck portion of the die body is honed to only take the neck .004" under finished size and the expander ball bumps it back up .002". I have tried using a Lee collet die with a larger mandrel to reduce the neck about half way first but couldn't tell any difference in runout.

 

[Richard Coody]

I took several Lapua .308 fired cases and picked one that is consistent with the others. Then measured using a .0005" readout caliper in 6 places before and after resizing. I set the Forster B/R F/L die for .001" shoulder setback to be sure I was contacting the case. Only the upper half of the case body is getting resized. .0015" at the top which is more than I would like to see. I know the neck expands a lot (stock Savage chamber) so cases get annealed every couple firings. The necks are turned to .014" thickness and the center of the neck runout on this one after F/L resizing is about .0007". The neck portion of the die body is honed to only take the neck .004" under finished size and the expander ball bumps it back up .002". I have tried using a Lee collet die with a larger mandrel to reduce the neck about half way first but couldn't tell any difference in runout.
View attachment 1017379

well what does your target tell you?

 

[T-shooter]

The last I fired, three consecutive groups of 3 at 215 yards were .550", .335", and .595". Probably need to test 10 shot groups F/L resized vs neck sized only. I was using these to pre-warm and foul the barrel to work up a load with Berger 200.20x which has a ways to go yet.

 

[ireload2]

Lose the calipers and use a good micrometer. You are fooling yourself making judgments based on the 4th decimal of a caliper. When you start beefing about .0015 on a diameter sizing being too much sizing, I will guarantee your other variables are too great to tell a difference on the target. You need to resize say about 100 cases and make them come from 4 or 5 different lots or headstamps.
That way you will have 20 to 25 cases of each headstamp. Fire all of them in your rifle.

Then at one setting FL resize all of them while rotating the resizing.
Your hand temperature and the press operation will probably cause the press frame to grow a little so rotate the sizing from one lot to the next. Do not resize all cases in a lot in sequence.

Then check all of your FL sized brass for the diameters with a mike. You will see some variation with a mike or an optical comparator. You will probably see no variation with calipers.

You might be able to detect variation in the shoulder bump with calipers and one of the shoulder bump comparators such as the Hornady tool. I would guess you will see at least .002 to .003 variation in the shoulder bump over 100 cases if you size the cases only one cycle without an expander ball.

Any longer cases can be recycled or rebumped a time or 3. Use more dwell at the top of the stroke and you will see the shoulders move back to a common length.

 

[T-shooter]

Lose the calipers and use a good micrometer. You are fooling yourself making judgments based on the 4th decimal of a caliper. When you start beefing about .0015 on a diameter sizing being too much sizing, I will guarantee your other variables are too great to tell a difference on the target. You need to resize say about 100 cases and make them come from 4 or 5 different lots or headstamps.
That way you will have 20 to 25 cases of each headstamp. Fire all of them in your rifle.

Then at one setting FL resize all of them while rotating the resizing.
Your hand temperature and the press operation will probably cause the press frame to grow a little so rotate the sizing from one lot to the next. Do not resize all cases in a lot in sequence.

Then check all of your FL sized brass for the diameters with a mike. You will see some variation with a mike or an optical comparator. You will probably see no variation with calipers.

You might be able to detect variation in the shoulder bump with calipers and one of the shoulder bump comparators such as the Hornady tool. I would guess you will see at least .002 to .003 variation in the shoulder bump over 100 cases if you size the cases only one cycle without an expander ball.

Any longer cases can be recycled or rebumped a time or 3. Use more dwell at the top of the stroke and you will see the shoulders move back to a common length.

The only micrometer I have has flat surfaces and won't work well on an angled case. The calipers I have read in 1/2 thousandths and I used the sharp edge of the blades and measured each several times while trying to slightly angle the case in the jaws to get as close as possible to perpendicular. The readings were repeatable at least to .0005". I just now remeasured the case after the temperature stabilized for a few hours and I get the same reading all the way down. A larger test batch would be better of course. I was trying to get some idea of how much I was working the brass. I don't know if I the upper portion of the die could be polished out a bit or if that's even enough to worry about.

Sometimes the shoulder bump can very up to .002" but probably in part due to the condition of the brass. Better if they are all freshly annealed. My press doesn't cam over and if I apply more pressure, it will compress a little more. I try to get everything to work from a very light stroke and then apply a bit more pressure a second time if necessary.

I'm sure the difference in size and internal volume would be beyond the scope of my ability to measure it on target but I like to try to eliminate as many variables as possible.

Thanks for the reply.

 

[ridgeway]

Sounds like you need a way to stop or cam over your press. The brass needs to dwell several seconds in the sizer die for consistent results. Sounds like a Lee press not allowing it to cam over and lock. You will never get consistent results by varying pressure by feel.

 

[T-shooter]

Sounds like you need a way to stop or cam over your press. The brass needs to dwell several seconds in the sizer die for consistent results. Sounds like a Lee press not allowing it to cam over and lock. You will never get consistent results by varying pressure by feel.

I don't think there is a way with this press. It is stopped by contact with the die and even though it's cast iron it still will flex enough to vary the measurements depending on how much force is used. Same way with seating. I can add .003"-.004" by applying more force to the handle after it has made light contact with the die. Normally I set for a light contact, measure, and correct if necessary. Never thought about dwell time but it makes sense so I'll try it.

I know a caliper is not an exact reading, probably +/- .001" compared to a micrometer, but is repeatable and will show an increase or decrease in size. I wondered if this is good for a F/L die to be this close to fire formed brass while bumping the shoulder back even though it's compressing more right at the shoulder. Cheap dies like the Lee undersize too much and overwork the brass.

 

[ireload2]

Your mike will work way better than your calipers. You are kidding yourself if you think calipers are better for anything except speed and convenience. You calipers may display in 1/2 thousandths but you are lucky to get plus or minus .001 out them accurately. Calipers are much more dependent on technique. Compare measurements of the same case. Measure it about 20 times each with calipers and mikes. By the time you have measured it 20 times with mikes you will have the technique down to probably about plus or minus .0002. With calipers you will still be getting the same old variable measurement that you think is plus or minus .0005 when it is actually much more. The mike will show you the difference. The caliper surface is also flat so you don't really have any advantage with the calipers.

Your shoulder bump varies because your technique varies and your technique is not robust enough to handle the brass variations.
This was copied from another post but it applies to any resizing operation where you find your head to datum length varying.
Sit down with about 100 to 300 cases and a Hornady or equivalent shoulder bump comparator.
Start resizing your cases with your normal process. Measure each case immediately after you size it so you have some memory of the force required. If you have small variations in the lubing technique, the speed of the resizing stroke and the dwell at the top of the stroke you will find small variations in the head to datum length (I will call it HDL).

These small variations will be about .002 max but if you are hasty and sloppy you might cause .003 variation. You can almost entirely eliminate these variations by taking a little more time.
1. Size the cases slowly. This gives the brass more time to creep (yield) to a common location.
2. At the top of the ram stroke let the ram dwell to a count of say 4 to 5 seconds.
3. Lower the ram 1/2 inch and spin your case about 120 degrees in the shell holder. Then resize slowly again and repeat the dwell again. Then lower the ram, spin the case one more time for 120 degrees and slowly size again with the dwell.

All of these motions give the brass more dwell time at the top of the stroke. The added strokes and dwell help to minimize spring back of the brass. Do this and your FL sized cases (when sized at one session) will all have the exact same shoulder bump length and your ammo will improve. The lube technique is not all of the problem. The problem is the single stroke sizing and the variations in speed. These variations combine with the lube variations to create varying head to datum lengths.
Most people cannot believe that they cause this kind of variation when resizing. Use the caliper and the bump gage to help you identify what is causing it and how to get rid of it. If you want consistent HDL you have to have a consistent resizing process and that means SLOW and REPEATED WITH DWELL.

The only micrometer I have has flat surfaces and won't work well on an angled case. The calipers I have read in 1/2 thousandths and I used the sharp edge of the blades and measured each several times while trying to slightly angle the case in the jaws to get as close as possible to perpendicular. The readings were repeatable at least to .0005". I just now remeasured the case after the temperature stabilized for a few hours and I get the same reading all the way down. A larger test batch would be better of course. I was trying to get some idea of how much I was working the brass. I don't know if I the upper portion of the die could be polished out a bit or if that's even enough to worry about.

Sometimes the shoulder bump can very up to .002" but probably in part due to the condition of the brass. Better if they are all freshly annealed. My press doesn't cam over and if I apply more pressure, it will compress a little more. I try to get everything to work from a very light stroke and then apply a bit more pressure a second time if necessary.

I'm sure the difference in size and internal volume would be beyond the scope of my ability to measure it on target but I like to try to eliminate as many variables as possible.

Thanks for the reply.

 

[critter_bill]

Not to belabor the point about calipers but the accuracy of them are usually stated as +/- .001" and micrometers are stated as +/- .0001". And, yes, technique matters greatly. Although I programmed and operated CMMs and Vision Systems in automotive precision measurement labs for years, I still would reach for a caliper or mic to verify when in doubt. I mostly used Mitutoyo digital hand tools but would imagine that Starrett, Brown and Sharpe, etc would be the same: the 4th digit on your calipers is considered an insignificant digit. It floats between .xxx0 and .xxx5 so it has no value. Although it displays four digits, it is still back to accuracy of +/- .001". Calipers are useful but mics get you down to tenths. Although I measured for nearly 30 years, I'd still trust a good tool and die man or top flight machinist with micrometer readings more than my own. Now, on the CMM....

 

[T-shooter]

I have a Mitutoyo 6" digital caliper, a Mitutoyo 6" dial caliper, and a 0-1" Mitutoyo micrometer. The digital caliper is listed as a 0.0005" resolution but still with a +/- .001" accuracy. If I use the calipers, I usually get the same repeatable reading on the same item, but it may not correspond exactly to the micrometer.

 

[critter_bill]

T-shooter, I'm in awe of your graphic for the case and dimensions. Nice work. Did you notice that all of your measurements on the graphic ended in 0 or 5? I use my calipers far more than my mics but I seldom worry about tenths unless I'm turning necks for my 6BR or 6PPC. I just recognize that I'm only reading to three decimal places. Looks like you're on your way to precision shooting. Welcome to the dark side.

 

[ireload2]

Your CMM cannot be trusted either unless you have ran gage R&R studies on it.
Even then differences in programs and programming technique can affect some measurements.

Not to belabor the point about calipers but the accuracy of them are usually stated as +/- .001" and micrometers are stated as +/- .0001". And, yes, technique matters greatly. Although I programmed and operated CMMs and Vision Systems in automotive precision measurement labs for years, I still would reach for a caliper or mic to verify when in doubt. I mostly used Mitutoyo digital hand tools but would imagine that Starrett, Brown and Sharpe, etc would be the same: the 4th digit on your calipers is considered an insignificant digit. It floats between .xxx0 and .xxx5 so it has no value. Although it displays four digits, it is still back to accuracy of +/- .001". Calipers are useful but mics get you down to tenths. Although I measured for nearly 30 years, I'd still trust a good tool and die man or top flight machinist with micrometer readings more than my own. Now, on the CMM....

 

[critter_bill]

True, it is the Indian, and not the arrow.

 

[T-shooter]

To properly measure a .308 case you need a micrometer with ball heads like the top example. The bottom version cannot sit on a tapered case and measure properly.

 

[critter_bill]

Like these? Sorry to intrude, T-shooter. Only trying to help.

 

[T-shooter]

View attachment 1017862

Like these? Sorry to intrude, T-shooter. Only trying to help.

Nice stands I mics, nice target.

 

[mikehotel]

Your shoulder bump varies because your technique varies and your technique is not robust enough to handle the brass variations.
This was copied from another post but it applies to any resizing operation where you find your head to datum length varying.
Sit down with about 100 to 300 cases and a Hornady or equivalent shoulder bump comparator.
Start resizing your cases with your normal process. Measure each case immediately after you size it so you have some memory of the force required. If you have small variations in the lubing technique, the speed of the resizing stroke and the dwell at the top of the stroke you will find small variations in the head to datum length (I will call it HDL).

These small variations will be about .002 max but if you are hasty and sloppy you might cause .003 variation. You can almost entirely eliminate these variations by taking a little more time.
1. Size the cases slowly. This gives the brass more time to creep (yield) to a common location.
2. At the top of the ram stroke let the ram dwell to a count of say 4 to 5 seconds.
3. Lower the ram 1/2 inch and spin your case about 120 degrees in the shell holder. Then resize slowly again and repeat the dwell again. Then lower the ram, spin the case one more time for 120 degrees and slowly size again with the dwell.

All of these motions give the brass more dwell time at the top of the stroke. The added strokes and dwell help to minimize spring back of the brass. Do this and your FL sized cases (when sized at one session) will all have the exact same shoulder bump length and your ammo will improve. The lube technique is not all of the problem. The problem is the single stroke sizing and the variations in speed. These variations combine with the lube variations to create varying head to datum lengths.
Most people cannot believe that they cause this kind of variation when resizing. Use the caliper and the bump gage to help you identify what is causing it and how to get rid of it. If you want consistent HDL you have to have a consistent resizing process and that means SLOW and REPEATED WITH DWELL.

Thanks for the heads up on this. I've been struggling with resizing brass, so I'm hoping this will help.

Thanks for posting

 

[ireload2]

No you don't. Your imagination is working overtime to prove your point when your point is just wrong. You do not need a radius on the mike faces any more than you need radii on your calipers. You simply learn to mike with the edge of the mike faces. It is all about touch and superior operator feel that you have with a micrometer.

Now think about what you said for a moment, A mike with both a spherical anvil and spindle face only has one spot in the dead center where you can get a good measurement. With 2 angled surfaces you cannot get right on the center because both surfaces are tangent to the anvil and spindle off center. Your suggested solution is sort of the worst of all evils.

Rather than continuing to argue about something you have obviously never done - go measure about 25 cases. Then measure one case 25 times then compare to your calipers. For serious measurement you should not depend on calipers.

To properly measure a .308 case you need a micrometer with ball heads like the top example. The bottom version cannot sit on a tapered case and measure properly.

 

[ireload2]

Having the Stony Point tool was an eye opener for me.
One day I sat down with it to form 100 cases for a 6.5X53R Dutch Mannlicher from new brass. In this day and age of very expensive brass I did not want to scrap any of it. So I measured each case as I zeroed in on the perfect die setting. I noticed the head to shoulder datum lengths varying about .002 depending on how much lube was used, how fast I sized and how much dwell was used at the top of the stroke. The final forming was done without a decapping pin and expander since all I had to form the brass was a trim die. Some of the cases came out about .002 too long. Yet they could be put back in the press and bumped another 2 to 3 times while rotating the brass. These extra bumps and dwells resulted in all of my cases having the exact same drag when closing the bolt on the formed cases. As a result I had formed 100 new cases without losing a single piece of brass and every piece of brass was a precise fit in my rifle.

Thanks for the heads up on this. I've been struggling with resizing brass, so I'm hoping this will help.

Thanks for posting

 

[T-shooter]

No you don't. Your imagination is working overtime to prove your point when your point is just wrong. You do not need a radius on the mike faces any more than you need radii on your calipers. You simply learn to mike with the edge of the mike faces. It is all about touch and superior operator feel that you have with a micrometer.

Now think about what you said for a moment, A mike with both a spherical anvil and spindle face only has one spot in the dead center where you can get a good measurement. With 2 angled surfaces you cannot get right on the center because both surfaces are tangent to the anvil and spindle off center. Your suggested solution is sort of the worst of all evils.

Rather than continuing to argue about something you have obviously never done - go measure about 25 cases. Then measure one case 25 times then compare to your calipers. For serious measurement you should not depend on calipers.

Sorry to obviously disappoint you but I wasn't born yesterday, or even the day before and I have worked with measuring equipment in several jobs over the course of my working career back to the early '70's. Machinist, inspection, engine builder, and several others. I think I know how to read a mic by now. On an angled case or any other angled surface, a flat face mic can only measure off the high side and only then if you can manage to get the exact center inline with the center of the object you are measuring. Not saying it can't be done but it's not easy, at least for me. Any measuring device also needs to be perpendicular to the centerline of the object or there will be an error in your reading. A ball head is much easier and probably more likely to be accurate given the possibilities of not getting the flat surfaces aligned properly.

And with calipers. I would use the sharp edge, not the flat wider surface for a measurement like this. And from my experience, most decent quality calipers are repeatable to 1/2 thousandth. I'm not saying you'll the the correct measurement as compared to a micrometer. Most all calipers are rated to +/- .001". The purpose of this post wasn't to show the exact measurement, just the variance after resizing.

Good luck to you in measuring any way you choose. I'll use a method that works!