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

[Nodak7mm]

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

 

[BoydAllen]

If you fire two cases from the same batch and resize one right away, and then wait a couple of weeks and size the other, just before you finish loading them both, the one that sat for a couple of weeks, between sizing and seating, will require more effort to seat the bullet. No disrespect intended, but why didn't you just do a little experiment?

 

[sailhertoo]

Then he would not have the opportunety to converse with such know all people like you.

No disrespect intended.

 

[necchi]

Yes, spring back is real.
I try to load'm and seat within 24hrs. (prep one day and load the next)
I've found waiting longer does indeed require more force too seat and that complicates concentricity issues.

 

[Travelor]

It would seem that if a case "springs back" with time it would do so whether a bullet had been seated or not................................

:-\

George

 

[Nodak7mm]

Rewinder: It was James Phillips post/study/experiement that I read several yrs back that got me thinking about this.

Geo: That is the same question I have. Answer to that one is above my pay grade...

Boyd: I would have performed an in-depth analysis, but I sent my test jig out for trueness testing, my force gauge out for calibration and my brass control sample out for material composition testing. Couple those setbacks and the fact the Fall Equinox occurs the weekend that I leave for Lodi, I figure it would behoove me to just ask the voices of experience... ;D

Regardless, good topic to discuss!!!

Thanks for your time.

Rod, still curious in Fargo!

 

[MGYSGT]

You don't suppose that, the inside of the neck gets a little tarnished while waiting and that results in more tension? I would think that springback happens rather quickly after resizing, just like it does after firing.

Tom

 

[artbosco]

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

RELOADING TIP--Neck Tension vs. Time:

We've learned that time (between neck-sizing operation and bullet seating) can have dramatic effects on neck tension. Controlling neck tension on your cases is a very, very important element of precision reloading. When neck tension is very uniform across all your brass, you'll see dramatic improvements in ES and SD, and your groups will shrink. Typically you'll also see fewer fliers.

Right now, most reloaders attempt to control neck tension by using different sized neck bushings. This does, indeed, affect how hard the neck grips your bullets. However, James Phillips recently discovered that another critical factor is at work. He loaded two sets of 22 Dasher brass. Each had been sized with the SAME bushing, however the first group was sized two weeks before loading, whereas the second group was neck-sized just the day before.

James noticed immediately that the bullet seating effort was not the same for both sets of cases--not even close. Using a K&M Arbor press equipped with the optional Bullet-Seating Force Gauge, James determined that over twice as much force was required to seat the bullets which had been neck-sized two weeks before. The dial read-out of seating force for the "older" cases was in the 60s, while the seating force for the recently-neck-sized cases was in the 20s. (These numbers correspond to pounds of force applied to the bullet).

Conclusion? In the two weeks that had elapsed since neck-sizing, the necks continued to spring back (get tighter) and stiffen. Lesson learned: for match rounds, size ALL your cases at the same time. If you want to reduce neck tension, load immediately after sizing.

Source: accurateshooter.com [It's somewhere on this site]

 

[in2deep]

FWIW the cleaner you get the insides of the necks the harder the seating force required and greater the neck tension. After going to the stainless media tumbling method the cases come out shiney squeeky clean and I was able to go down one bushing size lower to get the desired seating tension.

After testing a couple different neck tensions + - .002 in ladder tests it didn't seem to matter for group size they all shot great and I would bet that it's the same situation with time-lapse between sizing and loading..... basically a non-issue as long as they are all grouped and treated similarly .

 

[BoydAllen]

Where I noticed it was not nearly so scientific. Virtually all of my shooting and loading is done with and for may 10.5# 6PPC, at the range. In the past I would size and prime a set of cases (20 or less) and then load them in smaller groups while tuning or doing experiments. Sometimes I would have a few that had been sized that did not get loaded and fired at the end of a session. I would use them at the beginning of another day at the range. This would put me in a situation where I would start out with old sizing and switch to new. The difference in seating force, felt when using an arbor press, was large enough that no instrumentation was needed. It was obvious. My theory is when the brass is sized, that the grain boundaries of the metal are disturbed and slightly weakened, and that over time, they go back to normal, becoming narrower, stronger. This could all be nothing but unscientific malarkey, but until I get better information, it is my working theory.

Another example of this same phenomenon occurs when expanding case necks for turning. It has been my observation that one can expand necks, with a mandrel that gives a satisfactory fit for turning, and if one does not finish the job, that upon returning to the task several days hence, that the remaining cases' necks (that were previously expanded) will be slightly too tight, and have to have the same expander mandrel run through them again.

Currently, I am thinking of buying an extra 1" micrometer, to keep in my range kit. I plan on setting and locking it, and using it as a drag through gauge, to compare sized neck ODs to see if their is a correlation to the seating force required. Of course this would only be used for comparisons within sets of cases that have been turned to the same neck thickness, came out of the same box, and have been fired and FL sized each time. It it turns out that there is a correlation between sized neck OD and seating feel, I will probably do some chronograph testing as well, and at the end of it all, have come up with a useful sorting procedure. We shall see.

 

[BoydAllen]

In2deep,
What caliber, bullet weight, and powder did you do your test with? I have found that the importance of neck tension depends on what powder I use. For 133, better shooters than I (long list) have found that it "likes" a lot of neck tension. Based on that advice, backed up with some testing of my own, I switched to a tighter bushing. Some years ago, I had a scrap of 2015 that was probably manufactured in Israel. Testing showed that in addition to producing good groups, it worked well with different neck tensions, and that light tension worked well. Unfortunately, the 8# jug that I bought, that was manufactured in a different country, did not have the same virtues.

 

[Greg110]

OK, so now we have expanded the necks, immediately reloaded, and the rounds sit for X period of time. Now what happens to the neck tension over time? Do we have to control the time lapse from reloading to competition? Inquiring minds want to know!

 

[BoydAllen]

I have heard that some shooters, who preload for matches have seen improvement by loading early, and letting their ammo age a bit. I have not explored this, because in 1-200 yard benchrest, loads are adjusted during the day, and mixing "aged" loads with those that were not, would only complicate matters. If you want to pursue this, I would think that you would need to shoot new and older ammo over a chronograph, changing ammo for each group. One factor that tends to discourage holding ammo for years, is the very real possibility of bullets becoming cold welded in case necks.

 

[artbosco]

Do we have to control the time lapse from reloading to competition?

NO!

Hall of Famer Jim Borden: "I have my ammunition already loaded for [major matches]. It's working, both rifles are Agging in the 'low Ones', with a load of about 29.0gr N133, running about 3300 fps."

"Loading to conditions on match day can kill you. All you can do is go by memory and guess-timates. If your rifle has good vibration control, you'll typically have an accuracy window of 100-125 fps."

"I set preloads for velocity in the middle of the accuracy window which lets me shoot in any conditions. Studies by Jack Jackson convinced me we could let ammo sit for as long as a year and accuracy will hold."

 

[necchi]

Travelor, MGYSGT and Greg110,,
I'm not real good at explaining either, but as BoydAllen is saying spring back does continue with an empty case.
The issue of this springback or more tightening on a seated bullet continuing only happens a small, if at all, amount.

Let's say the matirx of the brass wants to return, as Boyd explains, to an undamaged form, with nothing to press against, it can move freely. When a bullet is present the brass reaches it's full amount of reshaping or "squeeze" sooner and stops. It's forced to stop changing because of another element, the bullet, and relaxes to that position. It doesn't have enough energy by itself to continue it's springback/squeezing action.

We can of course change tention by forcing the bullet into a smaller neck, (bushing size). In that kind of situation there is another factor pushing the brass out,(pressure from the bullet size).

Sorry if that doesn't make sence, like I said I ain't a good explainer. I understand it, and could probably show ya, but it's hard to define in words.

 

[jmm03]

Hi all,having read some of the same articles as some of you,I started paying more attention to my ammo by batch.I had loaded up 25 rounds almost immediately after neck sizing and then loaded up the other 25 approximately 3 weeks later.Exactly the same load in all . There was a noticeable difference in the point of impact at 600 yards from each set. Approximately 4 clicks of elevation and 2 of windage.Conditions were early morning,overcast,temp around 70 F,wind negligible. Not exactly scientific,but I did mark the rounds to separate them and there was a consistant difference between them that I could only attribute to the difference in the time they were loaded. Loads were 6.5x55,Lapua cases,BR-2 primer,142 Sierra HPBT,H4831
powder,out of a trued remington with a 27" Bartlien 5R 1-8.5.Jim

 

[BoydAllen]

Thanks for the info.

 

[Nodak7mm]

Necchi, Thanks, that makes sense.

Boyd, in all seriousness, thank you for your input and sharing of experiences.

Rod

 

[wapiti25]

I have found that the "neck weld" with time is real. When ammo was loaded and not shot the neck tension was greater with age. My match ammo would be loaded with the bullet seated long and then seated to the proper depth later just before the match. Worked for me. Try pulling a bullet after a year of setting, then load and pull within a few minutes. I have found less "neck weld" with fresh annealed brass. I have had the bullets give an audible "POP" when they would break lose on pulling aged ammo. I have had to bump some bullets deeper before the collet would grip enough to pull them out.

 

[bsoutlaw32]

Rod

After reading this post and pondering this idea, i don't think it has to do with spring back of the case neck! I think it has more to do with Corrosion or exposure of the brass to the air or contaminates for a couple weeks. One would have to take out that part of it to do a fair test! We all now how much different a bullest seats when brass is clean compared to brass with a little carbon in the necks!

Rod did you get that perfect 600y load worked out yet?

Brian