Time between sizing and seating; Does it have an effect?

[BoydAllen]

Sailhertoo,
It has been my experience that if one measures turned case necks that have just been sized with a bushing die, with no expander, that they are around a half thousandth or so larger than the size written on the bushing, when steel (coated or not) bushings are used. I have no way of accurately measuring the ID of bushings, so I cannot guarantee that this is an indication that the sized necks are springing back. If one then lets these sized necks "rest" for a couple of weeks, the force required to seat bullets increases. I have not done an accurate measurement of the ODs of sized necks over time. My gut feeling is that the brass in the sized necks hardens over time, but more checking to verify would be a good idea.
Boyd

 

[LongRanger]

Yes, time does matter. Interrupting your reloading process won't yield consistent results.

Brass cartridges are temperamental, unpredictable, and don’t wanna be messed with. Messing with them will yield mysterious results. Expand from the inside and they shrink. Squeeze from the outside and they spring back. And, from case to case out of the same lot which are all prepared the same way, some will do “it” more or less than the others.

I’ve had cases which had necks that refused to expand and stay expanded even when heated to a cherry-red glow, and I’ve had new cases which had necks that were dead metal from the get-go. And it’s pretty obvious from the results that all the rest fall somewhere in between.

So my continuing challenge has been to find 100 cases that I can group into batches of 20 each so that I can take them to the range and shoot a 5 x 1000 match and expect reasonable results.

Wish me luck.

Frank B.

 

[johara1]

Lynn, all military ammo is sealed on the bullet and the primer with the exception of match ammo, it is hard to pull except match. I pulled a lot of Lake city 173 and replaced them with 168 MK's
I have had the same things happen as Boyd said with the brass being sized and and left set for a week the force gage on the KM press will show an increase in seating effort on those left a week and the ones loaded that day and with the Dasher it is very noticeable at 1K in vertical .......jim

 

[mikecr]

Does "spring back" happen the other way too? ie: I use a neck sizing collet die so the neck ID is not resized to sub caliber dimensions thus there is no finishing step of an expander ball? Does the brass "spring back" to less neck tension over time?

What if you don't use a expander ball and just size the neck with a bushing? Will it tend to spring outward giving less neck tension?

Your last added energy is the expansion caused with bullet seating. So your brass will be trying to counter that expansion. No matter what.

Boyd, on the stepped sizing, I agree completely that it causes greater resistance to further seating.
And that this is not in the context of 'tension' but of remaining upsizing/seating force.
That is, you oversize downward to create a point where further bullet seating(with jam loading) would require way more force than bullet grip(springback tension) alone.
I do this in a sense, but for a different purpose(off the lands).
I adjust my downsizing length to affect tension, rather than downsizing amount. This allows the unsized neck energy to partially combine with the new balance point of the sized neck, to increase overall springback tension.

For the bushing users here, you can do a test to see that bullet grip amounts only to springback.
Just size necks down different amounts, enough for all the contrast you like. Seat bullets in them, pull those bullets, and then measure the neck ODs. They measure the same(1-3thou under cal), with only the hardness variance of your necks to cause relatively small deviations.
That springback is your bullet grip, no matter the force it took to seat those bullets(to upsize with that bullet seating).

 

[BoydAllen]

Mikecr,
Another little complication comes with flat base custom bullets that have a larger diameter right at the base, a pressure ring. If the sized portion of the neck does not extend past the base of the bullet, neck tension is limited, because the pressure ring expands the neck as the bullet is seated. If the pressure ring stays within the sized portion of the neck, bullet pull is increased. In seating bullets in cases where the sized portion of the neck does not cover the final position of the pressure ring, I can feel a reduction of seating force as it comes out of the sized portion. For a powder that "likes" a higher bullet pull, this is an undesirable situation.
Boyd

 

[mikecr]

I don't think it would matter. Pull force itself(without expansion) comes down to friction, and that would still be there because the pressure band would egress through the sized portion of neck.
And if I remember right, necks expand enough before a bullet even moves. This seal time(around the bullet) affects pressure peak & timing, but would also reduce friction as a factor.
With this, squeaky clean/hi friction necks would not affect MV over uncleaned/low friction necks.

But I haven't tested it myself.

 

[lynn]

Johara

Jim I use a force gage on my seating as well or atleast I used to.What I found was as long as all your rounds are similar you will get good results on the target.If you have tight rounds and loose rounds you will see it very clearly at 400 yards or longer.

The same holds true for neck clearance.If you have 10 loaded rounds that are tightly fitted necks(zero clearance) and 10 rounds that have 0.002 clearance you will get two distinct and very well defined impact points on your 600 yard targets.

For our competition guns will pre-load well in advance leaving our seating depth quite long and re-seat the night before the match.Some cases require very little effort to get initial movement on the bullet while others seem like your going to bend the press handle.
The next day however they all shoot just as good as the others.I wouldn't care how long my rounds sat as long as the final seating was all done the night before the match.That means I would shoot 5 rounds with a 1 month wait right along side rounds with no wait as long as they were all seated to the same length the night before.
Lynn

 

[BoydAllen]

Good information

 

[LongRanger]

All brass is born female and, as such, is designed to drive us nuts. Just as I think I have it figured out, it throws me another curve and does just the opposite of what I expected.

Just this morning I wanted to reload 15 rounds from 30 pieces of brass that were in every respect as identical as I could make them. All twice-fired, same weight, same length, same base to shoulder, same neck thickness and soforth. But I knew I'd have to do some culling once Isized the necks because the various pieces would not all grip a bullet with the same tenacity.

My first step after sizing all with the same .309 bushing die to the same length is to place a new bullet in every case, put it in my Wilson seater, and observe the amount of seating pressure indicated by my K-M force gage on the arbor press. I then group the cases by the amount of seating force. In this instance, 2 bullets fell to the bottom of the case, 2 barely registered 1 pound, 2 registered 1-1/2 pounds, 14 measured 2 pounds (my target for soft seating), 6 measured 3 pounds, and 4 measured 4 pounds.

I have learned that test-seating this way is like running the bullets over an expanding mandrel, but that with 7mm bullets 2# of seating pressure seems to be at the lower threshold where slight expansion does not cause permanent enlargement. Not so with 3# of seating pressure and above.

Since I needed one more case with 2# of pressure, I reseated a case that registered 3# and got lucky. It measured 2# the second seating. I say lucky, for it could just as easily have dropped to 1#.

Then, just for the heck of it, I took one of the cases which had registered 2#, pulled the bullet and reseated it. It jumped up to 3# seating pressure on this second seating, So I pulled bullets from 2-3 more 3 pounders until I got another 2# to complete my set,

After pulling bullets from my lot of 15 two pounders, I charged them with powder and seated new bullets in them. The new results were 2 which barely registered 1#, 7 which were at my 2# target, and 6 which ranged from 3# on up to 6# .

Go figure.

Before I got the K-M gage I used to win a few comps and set a few records and have more hair. Now I seem to be running backwards. I think its because my eyes have gone bad from squinting so much at the dial indicator on the force gage. I just know that getting an OHaus push-pull gage to measure force to pull the bullets from my cases would solve all the mysteries, but I ain’t going there

Moral of story……the effective working time between sizing and seating seems to vary from a few nano seconds up to a coupla weeks.

BTW, regarding light and heavy seating tension with the same bullet, charge, etc. I have run this test and get a fairly consistent 5-6 fps difference…..which could keep you in contention or send you home, depending on where the speed fits in your accuracy node.

Frank B.

 

[dogdude]

+1 for lynn on final seating the night before, give it a try at the range, not at the match. all best dogdude

 

[fguffey]

Curious about the time delay between sizing your case and seating the bullet. The longer the time delay, does it result less neck tension?

If a reloader had a gage that measured tension the reloader would know what tension was. The first tension gage I operated measures in thousands of pounds, to save money to get a reliable reading we had to multiply the reading by the number of lines thrown over the crown, I believe I was 15 at the time.

And finally someone built a hydraulic press for seating bullets. The manufacturer added a gage, I was not surprised the gage measured pressure in pounds and no one else noticed there was no conversion from pounds to tensions.

F. Guffey

 

[StevenDzupin]

If a reloader had a gage that measured tension the reloader would know what tension was. The first tension gage I operated measures in thousands of pounds, to save money to get a reliable reading we had to multiply the reading by the number of lines thrown over the crown, I believe I was 15 at the time.

And finally someone built a hydraulic press for seating bullets. The manufacturer added a gage, I was not surprised the gage measured pressure in pounds and no one else noticed there was no conversion from pounds to tensions.

F. Guffey

Is there a formula for converting pounds to tensions ?
Google was of no help!

 

[StevenDzupin]

All brass is born female and, as such, is designed to drive us nuts. Just as I think I have it figured out, it throws me another curve and does just the opposite of what I expected.

Just this morning I wanted to reload 15 rounds from 30 pieces of brass that were in every respect as identical as I could make them. All twice-fired, same weight, same length, same base to shoulder, same neck thickness and soforth. But I knew I'd have to do some culling once Isized the necks because the various pieces would not all grip a bullet with the same tenacity.

My first step after sizing all with the same .309 bushing die to the same length is to place a new bullet in every case, put it in my Wilson seater, and observe the amount of seating pressure indicated by my K-M force gage on the arbor press. I then group the cases by the amount of seating force. In this instance, 2 bullets fell to the bottom of the case, 2 barely registered 1 pound, 2 registered 1-1/2 pounds, 14 measured 2 pounds (my target for soft seating), 6 measured 3 pounds, and 4 measured 4 pounds.

I have learned that test-seating this way is like running the bullets over an expanding mandrel, but that with 7mm bullets 2# of seating pressure seems to be at the lower threshold where slight expansion does not cause permanent enlargement. Not so with 3# of seating pressure and above.

Since I needed one more case with 2# of pressure, I reseated a case that registered 3# and got lucky. It measured 2# the second seating. I say lucky, for it could just as easily have dropped to 1#.

Then, just for the heck of it, I took one of the cases which had registered 2#, pulled the bullet and reseated it. It jumped up to 3# seating pressure on this second seating, So I pulled bullets from 2-3 more 3 pounders until I got another 2# to complete my set,

After pulling bullets from my lot of 15 two pounders, I charged them with powder and seated new bullets in them. The new results were 2 which barely registered 1#, 7 which were at my 2# target, and 6 which ranged from 3# on up to 6# .

Go figure.

Before I got the K-M gage I used to win a few comps and set a few records and have more hair. Now I seem to be running backwards. I think its because my eyes have gone bad from squinting so much at the dial indicator on the force gage. I just know that getting an OHaus push-pull gage to measure force to pull the bullets from my cases would solve all the mysteries, but I ain’t going there

Moral of story……the effective working time between sizing and seating seems to vary from a few nano seconds up to a coupla weeks.

BTW, regarding light and heavy seating tension with the same bullet, charge, etc. I have run this test and get a fairly consistent 5-6 fps difference…..which could keep you in contention or send you home, depending on where the speed fits in your accuracy node.

Frank B.

Frank,how does the dial gage indication relate to pounds of seating force ??
Just curios.

 

[halo68]

Hi Guy's
I did not read all the posts on this thread, but enough to maybe explain what i noticed with my brass. I resized, trimmed. and cleaned primer pockets on 25 .308 win. Norma brass, after prep. brass i took 5 pieces of brass, (one from each row) and tried them in my Rem. VLS 308. They went in nice and easy, bolt closed with no problem, no resistance, a couple of days went buy and i was going to charge and seat bullets but before doing it i ran the same 5 pieces of brass back into the chamber and the bolt seemed slightly harder to close. My ? is should i run all 25 pieces of brass thru the resizing die before i charge and seat the bullets.
Thanks
halo68

 

[dmoran]

@fguffey -
You replied to a 5-1/2 year old thread (from 2011) .... lol ...

 

[fguffey]

My ? is should i run all 25 pieces of brass thru the resizing die before i charge and seat the bullets.

halo68, I do not get into mortal combat with things I have no control over. It is possible reloaders are becoming micro managers of brass. Brass could have jump back, snap back or spring back, if it does the reloader should take a few lessons in discipline. I am the fan of measuring before and again after; that would be before firing and again after firing 'and' before sizing and again after sizing. If the case is jumping back after sizing the reloader should know 'by how much?' It was nice for the bolt to close on the sized case but a reloader that is in the habit of cutting it close should shorten the case from the shoulder to the case head an additional .001" to .002".

I understand it sounds like a reloader knows what they are doing when they claim they bump the shoulder .001" etc. and they always add the word bump, I have always thought the word 'bump' sounds like something involved in an accident. I have presses that bump, the instructions claim the press is called a bump press because the press is a cam over press. My presses that are not cam over presses do not bump because they are not cam over presses.

F. Guffey

 

[expiper]

watch out for those things that go "bump" in the night !!!!....especially the female ones,,,Roger

 

[savagedasher]

I don't think brass will stress harden very fast . The reason for the seating force change in pressure brass will tarnish in short time period . The seating forces comes from tarnish not the resistance or hardness .
The cold weld you get is from tarnish bonding
Both brass and copper tarnish so they both bond . When you have two perfect surfaces they bond . Take two perfect surface and put them together and try to pull them apart it is almost imposible. No add a drop of oil and work the air out and And it get impossible . You can't break the resistance of a perfect surface .
Cleaning of brass only makes the surface Clean and porous or rough so it takes greater resistance to seat. Then add tarnish in the equation .
That is why seating force increases with age . It is the same with release resistance
The great area a bullet is seated the more resistance it has to release . That is the reason I won't used sonic cleaner or stainless for loading target loads .
Clean surface has large resistances to load and tarninish faster . That is me you all can do it your way . Good shooting Larry

 

[BoydAllen]

In short range benchrest we do not clean all of the powder fouling out of our necks (because we get more uniform seating force, if we do not) , so the differences in seating force will never come from the a change in friction due to oxidation forming. The bullet does not touch the brass whether the bullet is seated right after sizing or when that seating is delayed. Also, I never clean the oxidation off of the outside of my cases. I only remover the powder fouling off of the outside of the case necks, but never to the point where they become bright. I am always somewhat amazed when people disagree with the results of a test that they apparently have not done, particularly when something has been reported by a number of experienced sources. Also, tuning by changing bushing size is a firmly established method in short range shooting. While not as common as fiddling with powder charge and seating depth, test have shown it to effect tune. The reason that I mention this is that the effect of time on the results of sizing, shows up in the force required to seat bullets (in a similar fashion to the effect of going to a smaller bushing) , and at longer range where groups form on the target. (Thanks to the poster who shared that.) I will have to try to remember to measure some cases very carefully (OD) just after sizing, and then to remeasure them over time. If anyone gets this done, I would appreciate hearing what your results were. If the ODs do not change, then it seems that the brass itself would have to have become harder for the seating force to increase. We shall see.

 

[Webster]

Curious about the time delay between sizing your case and seating the bullet. The longer the time delay, does it result less neck tension?

Read a semi controlled observation performed by a top shooter some yrs ago. How, I cant remember, but he measured the seating psi it took for a case just sized and then the bullet seated and did so the same for a case he sized and waited for "X" amount before seating. If I remember correctly the gist was he was of the belief that you should seat as soon as you can after sizing? The write up made sense, but on the other hand I am not a metalurigist.....

Looking for comments, thoughts, experiences, etc. Wondering while trying to prepare brass & loads for the Nats in Sept.. Also, how do you go about preparing a large amount of rounds for large matches, all at once or piece meal when you find time?

Curious in Fargo....

Rod

From the experts. Brass stress relaxes with time it doesn't increase. I understand some reloaders say if the brass sits around before seating a bullet it takes more force. There is no mechanism to increase the stress with time. Alternate facts persist.

https://www.copper.org/applications/industrial/DesignGuide/performance/tempstress03.html

https://www.copper.org/applications/industrial/DesignGuide/performance/temper03.html