Case trimming before or after resizing

[cw308]

Back in the days I think , people that reloaded were into precision target shooting . Now with the AR's alot like to throw alot of lead down range , cost savings or just a good day at the range . I enjoy benchrest shooting , I shoot 30 rounds per range trip and even only shooting 30 rounds I wouldn't think of cleaning up the case necks with a file , maybe if that was the only way back then . Using a turret press brought this up . I would think sizing and trimming would be on a single stage then go from there . Only used a single stage so I guess I not the one to give advice .

[F. Guffey]

Back in the days I think , people that reloaded were into precision target shooting . Now with the AR's alot like to throw alot of lead down range , cost savings or just a good day at the range . I enjoy benchrest shooting , I shoot 30 rounds per range trip and even only shooting 30 rounds I wouldn't think of cleaning up the case necks with a file , maybe if that was the only way back then . Using a turret press brought this up . I would think sizing and trimming would be on a single stage then go from there . Only used a single stage so I guess I not the one to give advice .

Trimming with a trim die and file can not be new information for anyone that has been on this forum for a year. And then there are those that choose to ignore good information. When forming cases there are times trimming requires 36" of trimming for 100 cases; add that to the time saved when forming 400 cases. That would be 144" of trimming,

Back to the aircraft counter sink. You have no interest in the hack saw and file so I will assume you have no interest in the counter sink method and or technique. I doubt another member has the ability to enlighten you or anyone else; but if it is the flat rate thing with time in motion the step sequence of trimming with a counter sink , forgive, I know I am wasting my time.

F. Guffey

[cw308]

Guff
My world in reloading is a small one , mostly 308 and 45acp . I never created a caliber from another , going that route I can see using different equipment , So I'm sorry for thinking so small . When I'm wrong I'll admit it . I enjoy reloading , I'm just a one gun guy , been shooting the same rifle since 02 and don't even have the itch to shoot another . I would like to see a trim die and file in action. Forming your own case for a odd caliber is an accomplishment . Again Sorry F. Guffey for thinking so small .

Chris

[hdwhit]

LukeB asked:
...where in your process do you trim your rifle casings?

Trimming is always done after resizing since it is generally the friction inherent in the resizing operation that draws cases to a longer length which is a contributor to what necessitates trimming.

[F. Guffey]

Trimming is always done after resizing since it is generally the friction inherent in the resizing operation that draws cases to a longer length which is a contributor to what necessitates trimming.

I could ask how 'it is' the shoulder gets moved back whole the brass moves. migrates, flows toward the neck end of the case when reloaders insist the flow is in the opposite direction; reloaders insist they move the shoulder back and when making tiny adjustments to the length of the case from the shoulder to the case head they insist they can 'bump' the shoulder back.

Again, I insist it is impossible to move the shoulder back with a die that has case body support.

As to the other part: As in trimming is always done after sizing; I have given at least three examples that prove that is not true.

F. Guffey

[totaldla]

Back before I started neck-sizing 30-30, I would trim after FL-resizing. Seems like 30-30 was super stretchy.

[F. Guffey]

Back before I started neck-sizing 30-30, I would trim after FL-resizing. Seems like 30-30 was super stretchy.

Stretch or flow or both? Cases with long tapered case bodies required trimming; most of the old tapered cases had rims. I understand that means nothing to most but if the case stretched it was between the case head/rim and case body. One of the greatest things that ever happen to the case is the shoulder and P.O. Ackley.

That created another problem? And then it goes back to case stretch and or flow or is it both?

And then there is the mystery that surrounds flow. Some reloaders have the case moving it two directions. One the one hand they claim they can move the shoulder back when sizing and they claim they can make finite adjustment by 'bumping'.

Bumping is cool; I have bump presses, my bump presses bump twice, once on the way up and again on the way down.

F. Guffey

[totaldla]

Originally Posted by F. Guffey

Stretch or flow or both?

Both. Loads near max pressure stretch a lot (I measured) and after FL-resizing they had "stretched" some more (I measured). But I clearly don't know if they were stretching vs flowing during FL-resizing - but the process was working the brass.

Anyways, this is one of the reasons I went to neck-sizing only on my 30-30 brass. It still stretched to a point, but I didn't keep records on how much per successive firings (my bad).

[Unclenick]

The difference is the location. In firing, the stretch occurs where the pressure ring forms. That falls at the location where brass thin enough for the pressure to stick it to the chamber transitions to brass too thick for pressure to stick it to the chamber, as by the head or, for more tapered case walls, a way up from the head. The unstuck part is still free to move and does so by stretching the case at that location.

In resizing, brass is first lengthened from that fireformed stretch by the die squeezing the sides of the case inward which lengthens the case from head to shoulder. Then as the sizing stroke continues, the shoulder of the case runs into the shoulder in the sizing die, and as you push further you extrude brass from the shoulder into the neck and from the body into the shoulder by displacement flow. So the distance from the head to the case mouth gets even longer, despite the fact the resulting case head to shoulder measurement will be shorter. (See the illustration in my post #23 in this thread.)

[gwpercle]

Anyone remember the old school trimmer... a hardened die , the case was inserted into the die and any part of the neck that stuck out was trimmed off with a file .
You kept filing until the neck was flush with the top of the die .
Then removed the case and used the chamfering and deburring hand tool .

Two kinds of dies...one threaded into a single stage press with the case in the shell holder and run up and into the trim die .
The other die was unthreaded and was simply held in your left hand on a flat solid surface with the file in you right hand to do the filing/trimming .

Talk about your "back to basics " trim tool...these was it ! I still have some hand held Herter's trim dies...they still work too !
Gary

[Bart B.]

The more a case has to expand to fill the chamber when fired, the more its length will decrease.

The more a fired case is sized down by dies, the more its length will increase.

My 308 Win case lengths decreased about .002” when fired then increased about .003” when full length resized. About .001” increase in case neck length every shoot/resize cycle.

No difference in accuracy across a .010” spread in case length, .2.000” to 2.010”.

SAAMI case and chamber specs show several thousandths case mouth clearance to the chamber mouth when the case is against its headspace limits. This allows the case neck to lengthen from the firing pin’s (or bolt closing) impact force pushing the shoulder back without the mouth being crimped into the bullet by the angled chamber mouth like some bullet seating dies do.

[F. Guffey]

The more a case has to expand to fill the chamber when fired, the more its length will decrease.

The more a fired case is sized down by dies, the more its length will increase.

My 308 Win case lengths decreased about .002” when fired then increased about .003” when full length resized. About .001” increase in case neck length every shoot/resize cycle.

No difference in accuracy across a .010” spread in case length, .2.000” to 2.010”.

SAAMI case and chamber specs show several thousandths case mouth clearance to the chamber mouth when the case is against its headspace limits. This allows the case neck to lengthen from the firing pin’s (or bolt closing) impact force pushing the shoulder back without the mouth being crimped into the bullet by the angled chamber mouth like some bullet seating dies do.

Everything a reloader needs to know: Not quite because if what you claim is true and the shoulder of the case is against the shoulder of the chamber when fired the case has no choice but to stretch between the case head and body. Meaning? Your case got shorter between the end of the neck and case head but longer between the shoulder and case head.

I have fired cases that that resulted in having case bodies, shoulders and no necks. If the shoulder of the case was against the shoulder of the chamber it would be impossible for the neck to become part of the shoulder.

F. Guffey

[Unclenick]

I had one of those brought to me once. I was working up loads at the range. A fellow who was a guest was there sighting in a hunting rifle. He came up to me with the shoulderless .308 case and asked me if that was normal. I said no. I looked at the rifle and asked if the cartridge had needed a little extra force to close the bolt. He couldn't tell. The rife had been borrowed from a friend who told him he was loaning this fellow his .308 for hunting, so he wasn't familiar with the rifle. I had looked at the gun, which was stamped ".30-06 Springfield" on the barrel.

[cw308]

Uncle
What went through your mind after seeing it was a 06 . I had a guy next to me at the bench that was shooting a 308 , luckily I carry a stuck case remover , he kept blowing the case headspace off the body , I said what charge are you loading . he said well over max I like speed . I was at a loss for words and moved two benches down to the left . Almost as bad as shooting a 308 out of a 06 . I just remembered guy shooting next to me needed help sighting in his scope , I said sure , when I looked through his scope the crosshairs were at 10 and 2 . Makes you wonder .

[Bart B.]

Originally Posted by cw308

Uncle
What went through your mind after seeing it was a 06 . I had a guy next to me at the bench that was shooting a 308 , luckily I carry a stuck case remover , he kept blowing the case headspace off the body , I said what charge are you loading . he said well over max I like speed . I was at a loss for words and moved two benches down to the left .

Please explain what the "case headspace" is that kept blowing off.

[cw308]

Bart B
It was the case head came out with the bolt the body was stuck in the chamber . My computer changed case head to headspace for some reason , I should have proofed before pulling the trigger . It does sound strange , sorry .

[Reloadron]

I believe cw308 just meant the case heads were blowing off or what is generally referred to as incipient case head separation. Since cw308 mentions:

I said what charge are you loading . he said well over max I like speed .

I can only assume the shooter was reloading and reloading brass which was stretched and not checked for the normally pronounced ring above the solid web of the case. Something is going to give, especially when exceeding load limits with questionable brass.

Anyway, I just see this as misuse of a term in saying "case headspace" blowing off rather than saying "incipient case head separation" which would likely have been the correct term or simply case head separation.

That's my guess and I am sticking to it!

<EDIT> I see cw308 cleared it up as I slowly typed and watched it rain. </EDIT>

Ron

[cw308]

Thanks Ron for the 6 it's raining here too
Chris

[Unclenick]

Ron,

It's close. Incipient means just beginning to happen or become apparent. So incipient head separation usually means you see the first sign of a circumferential crack at the pressure ring, often with a little smoke stain around it. This indicates the head is about to blow off and you should not try to get an additional load cycle out of it. It sounds like CW308 just witnessed complete head separation all at once with no incipient warning.



CW308,

Not having seen it before then (though several folks have posted pictures of other such cases on the Internet; I just couldn't locate one quickly), I was puzzled by the shape for a moment, but then thought to look at the rifle chambering as not much else could cause that.

[F. Guffey]

Originally Posted by cw308 View Post
Uncle
What went through your mind after seeing it was a 06 . I had a guy next to me at the bench that was shooting a 308 , luckily I carry a stuck case remover , he kept blowing the case headspace off the body , I said what charge are you loading . he said well over max I like speed . I was at a loss for words and moved two benches down to the left .

So much for the firing pin driving the case forward; if the extracted case did not have a shoulder and or neck the firing pin did not drove the case forward but if it had driven the case forward the case would still have a neck and shoulder.

And then there is the extracted case without a case head. The case does not have head space, it should be obvious to most how confusing it is for reloaders that believe the case has head space.

I am not infatuated with head space, I have that thing whittled down to the point most should be able to handle 'it'. I off set the length of the chamber with the length of the case from the shoulder to the case head.

CW308 removed a case with a case extractor and then started the routine with the case having head space. The clearance between the chase and chamber (front or back of the case?) could have been 'ZERO' meaning the case could not be moved before firing but if the case had head space anything is possible.

CW308 claims he removed a case because something had head space and then on something that did not have head space before the trigger was pulled.
And then we have to start over. The case locks onto the chamber when fired, That leaves me as the only one that understands case head separation with no clearance between the bolt face and case head or between the shoulder of the case and shoulder of the chamber.

Reloaders have this problem with pressure and primers; not me, when there is a chance something could go wrong I measure the case head diameter. A normal case head expansion is .00025" for a factory round. Again, I have had case heads expand in diameter to a point reading the case head stamp was difficult.

At the same time, if the case head expanded the flash hole increased in diameter and the primer pocket also expanded. While at the same time the distance from the cup above the web to the case head decreased when the case head expanded.

Crushing the case head caused the case head to move back whole the case body was locked to the chamber. And of course we do not know the condition of the cases before firing. The expansion of the case head is a dead giveaway of high pressure.

Again, a friend in North Texas removed a case from a rifle chamber. The rifle was a 25/06 and the round he removed was a 308 W. It took him 2 hours, all the sweaters were making bet on the length of the bullet when it left the barrel. Is a difficult thing to do when trying to carry a conversation with that group.

F. Guffey

Forgive, it was not possible to read the head stamp on the case he removed, he insisted on a receipt from the shooter. The shooter purchased the ammo that morning.

[Reloadron]

Ron,

It's close. Incipient means just beginning to happen or become apparent. So incipient head separation usually means you see the first sign of a circumferential crack at the pressure ring, often with a little smoke stain around it. This indicates the head is about to blow off and you should not try to get an additional load cycle out of it. It sounds like CW308 just witnessed complete head separation all at once with no incipient warning.

Definately a my bad and thanks for pointing out the error in my terminology.

Incipient: In an initial stage; beginning to happen or develop.

The clue being hasn't happened yet.

Thanks
Ron

[Unclenick]

Originally Posted by F. Guffey

So much for the firing pin driving the case forward; if the extracted case did not have a shoulder and or neck the firing pin did not drove the case forward but if it had driven the case forward the case would still have a neck and shoulder.

The extractor hook would stop it long before it got there. In the Remington rifle involved, the ejector would have put the cartridge forward against the extractor hook before the trigger was ever pulled, but clearly, it had enough firing pin protrusion to ignite the primer.

I don't think cases can move forward to an unlimited degree, but we know they tend to wind up forward because of the creation of pressure rings, which can't happen if the case is back against the bolt face when expansion occurs. In most modern rifles the ejector presses the case forward like in the Remington, but even for those that have no spring-loaded ejector plunger, the velocity imparted by the firing pin can be pretty slow and still get the cartridge there.

This DOD article shows that between primer strike and ignition there is on the order of a millisecond to two of delay during which the cartridge is loose to move forward as the powder burn gets established and swells the brass enough to stop it from moving freely. Even if there were no such delay, pressure rise plots show half to three-quarters of a millisecond is needed for rising pressure to stick cases. So, if you had, say, 0.004 inches of excess headspace (shoulder clearance) in an old Mauser or Springfield or a single-shot or lever action rifle that had no spring-loaded ejector pushing the case forward already, and had a 0.001s ignition delay, then:

0.004 in/0.001 s = 4 in/s = 0.33 ft/s average velocity needed for the cartridge to cover the 0.004" shoulder clearance distance in one millisecond.

The average velocity is the average of the starting velocity, v₀, and the final velocity, vf so it actually has to be accelerated to a peak value of twice that number, or 0.67 ft/s by the firing pin and/or primer pushing itself back from the primer pocket.

vaverage = (v₀+vf)/2 = (0 fps + 0.67 fps) / 2 = 0.33 fps

0.67 fps/0.001 s = 670 ft/s² acceleration

If the cartridge weighs 400 grains (30-06 with 150 grain bullet), then,

400 grains / 229,183 grains/slug = 0.00175 slug

F= ma

so, F = 0.00175 slug × 670 ft/s² = 1.175 lbs of force

That's not a lot of force to expect from the firing pin impact and it can easily move the cartridge forward before ignition is fully underway. It's not amazing that it happens.

[cw308]

Guffey
Headspace was a computer add on for some reason , case head is what I wanted to post . I always get slapped in the back of the head for saying headspace . I should know better , it's the distance between both ears .

[Bart B.]

I have seen dozens of 7.62 NATO fired cases that were ejected from 30-06 Garands. Shoulders were about 1/16" long.

One guy had 18 on the ground around him before his score keeper mentioned it.

[F. Guffey]

The extractor hook would stop it long before it got there. In the Remington rifle involved, the ejector would have put the cartridge forward against the extractor hook before the trigger was ever pulled, but clearly, it had enough firing pin protrusion to ignite the primer.

Control feed or push feed: And then there is the assumption the extractor jumps the rim of the case. I can not say most but a few understand the ideal of having the case ahead of the extractor when the case is fired is a bad habit.

F. Guffey

Back to most; when the bolt closes the chamber goes dark and there goes the light.