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

[BoydAllen]

A little tip on getting square case mouths....Turn the case instead of the cutter. The Redding trimmer works that way, and all of the trimmers that index off of the case shoulder can be used that way. For those just hold the trimmer in a constant relation to the case. It can be cocked a little and it will not matter. Just leave everything in position as you spin the case with a power adapter and drill. If the cutter spins and the case does not, everything has to be perfect to get square case mouths. Probably the slickest shoulder indexing trimmer is the one by PMA Tool, it works for multiple calibers and is easy to set precisely. Others are single caliber and once they are set up work fine.

 

[fgregorio]

A little tip on getting square case mouths....Turn the case instead of the cutter. The Redding trimmer works that way, and all of the trimmers that index off of the case shoulder can be used that way. For those just hold the trimmer in a constant relation to the case. It can be cocked a little and it will not matter. Just leave everything in position as you spin the case with a power adapter and drill. If the cutter spins and the case does not, everything has to be perfect to get square case mouths. Probably the slickest shoulder indexing trimmer is the one by PMA Tool, it works for multiple calibers and is easy to set precisely. Others are single caliber and once they are set up work fine.

Makes absolute perfect sense.
I'll look into that tool.
Always looking for the best mouse trap

 

[BenPerfected]

.

I have taken my Wilson seater and final seated the bullet just before shooting each .
I never see a improvement on target if anything it was not as good . It could be what I was seeing was the condition was changing and I didn't see it . No change in ES . Larry

What if the brass has already expanded before the bullet moves?

 

[fguffey]

Put a case on the shellholder. Bring the ram up. Screw the die in until it makes very firm contact with the shellholder and screw it in another half turn. With firm contact with the ram up, tighten the die lock ring.

It is not that I find fault with that arrangement but 1/4 additional turn after the die contacts the shell holder is the same as lowering the die .017". I know; that warrants an explanation; Lowering the die an additional .017" increases the presses ability to overcome the cases' ability to resist sizing. So if a reloader insist on returning the case to minimum length/full length sizing I agree, lower the die an additional 1/4 turn after the die contacts the shell holder. But; I never assume the reloader know and understands the press they are using, some presses are cam over presses and other presses are not a cam over press. Now I will tell you that is not something a reloader can get their minds around.

So, reloaders should make their minds up when it comes to sizing the case. If they adjust the die down an additional 1/4 turn after contact they can forget shortening the case .002" from the shoulder to the case head or as they say 'bump the shoulder back'. And then there are all of those reloaders that have problems closing the bolt on a sized case; none of them have a way of determining if the press, die and shell holder sized the case. If I want to know if my press has the ability to overcome the cases' ability to resist sizing I use a feeler gage to measure the gap between the bottom of the die and top of the shell holder; after all that is the reason the reloader gave the die an additional 1/4 turn after 'firm' contact.

It is easier for me to reduce the length of the case from the shoulder of the case to the case head .002" than it is to reduce the length of the case .005" from the shoulder of the case to the case head; especially when returning the case to minimum length/full length size.

F. Guffey

 

[fguffey]

And again, I did not say I moved the shoulder back because I find moving the shoulder back with a die that has case body support impossible to do. Again, bump; bump is something my cam over presses does when it hits the top, stops and then changes directions, I did not say it did not sound cool, I did say bump sounds like an accident.

F. Guffey

 

[fguffey]

What if the brass has already expanded before the bullet moves?

That is a tuff one, for years reloaders have allowed themselves to be conditioned to 'repeat the choir'. For years reloaders have quoted each other; starts something like the firing pin strikes the primer and then everything takes off for the front of the chamber etc. etc. and I ask; did they leave something out? The only responses I get are from compulsive gigglers.

F. Guffey

 

[M-61]

Just to add to BenPerfected's question:
If a cartridge develops 50,000 PSI where is the bullet when this peak is reached? Still in the neck? I know this happens quickly but it is not instantaneous. (explosion vs burn). My thought, which is based on nothing, is that on it's way UP to 50,000psi the pressure has to overcome the neck tension and the bullet would not still be sitting in the neck where it was loaded. I'm probably missing a bunch here.

 

[BoydAllen]

Just to add to BenPerfected's question:
If a cartridge develops 50,000 PSI where is the bullet when this peak is reached? Still in the neck? I know this happens quickly but it is not instantaneous. (explosion vs burn). My thought, which is based on nothing, is that on it's way UP to 50,000psi the pressure has to overcome the neck tension and the bullet would not still be sitting in the neck where it was loaded. I'm probably missing a bunch here.

If you scroll about half way down this page you will have your answer, which is that the bullet is a short way into the barrel when pressure reaches its peak.
https://en.wikipedia.org/wiki/Internal_ballistics

 

[JRS]

Just to add to BenPerfected's question:
If a cartridge develops 50,000 PSI where is the bullet when this peak is reached? Still in the neck? I know this happens quickly but it is not instantaneous. (explosion vs burn). My thought, which is based on nothing, is that on it's way UP to 50,000psi the pressure has to overcome the neck tension and the bullet would not still be sitting in the neck where it was loaded. I'm probably missing a bunch here.

www.hornady.com/ballistics-resource/internal

 

[BoydAllen]

I clicked on the link to the information on the Hornady site, and after reading a bit had to smile because it contains the exact description of what happens to a rimless case as it is fired that FGuffey has made so many negative remarks about. Perhaps HE should click on the link and do some reading. Another reason for my smile was that I had come to the same conclusion before reading it, based on my own observations.

 

[JCUtah]

I have heard various theories over time. Some of the topics here have been some of what I heard. So I decided to put it to the test today.

Here is the data by size. 5 shot groups. 300 yards. Out of Old Blue (ftr rig). 6 day is 6 day old neck sized, 1 day is 1 day old neck size. Moly is moly brushed in the neck. 11 months is just that, nearly a year sitting around. Neck sizing was done with a lee collet die. Lapua brass 3rd round of firing.

6 day 1.48"
1 day moly 1.71"
1 day moly pulled bullets 1.79"
6 day moly 1.94"
11 months 2.49"
1 day 3.42"

Speed-
6 day moly average 2700, SD 8.3
1 day moly average 2709, SD 7.3
11 months average (different lot of powder, varget) 2727, SD 11.7 (higher than load development with this lot of powder by 6.7 fps)

I understand this is literally a game of inches. But seems to me some of this is making a safari out of a squirrel hunt. Wind, mirage, me; it's effects me more than a "stale" round probably. I wish I was better at all the other stuff so the issues discussed here would be the only thing holding me back.

Anyway it was fun. Learned pulled bullets from load testing are worth recycling and it was good to knock more rust off the the comp next week.

 

[Mulligan]

I have heard various theories over time. Some of the topics here have been some of what I heard. So I decided to put it to the test today.

Here is the data by size. 5 shot groups. 300 yards. Out of Old Blue (ftr rig). 6 day is 6 day old neck sized, 1 day is 1 day old neck size. Moly is moly brushed in the neck. 11 months is just that, nearly a year sitting around. Neck sizing was done with a lee collet die. Lapua brass 3rd round of firing.

6 day 1.48"
1 day moly 1.71"
1 day moly pulled bullets 1.79"
6 day moly 1.94"
11 months 2.49"
1 day 3.42"

Speed-
6 day moly average 2700, SD 8.3
1 day moly average 2709, SD 7.3
11 months average (different lot of powder, varget) 2727, SD 11.7 (higher than load development with this lot of powder by 6.7 fps)

I understand this is literally a game of inches. But seems to me some of this is making a safari out of a squirrel hunt. Wind, mirage, me; it's effects me more than a "stale" round probably. I wish I was better at all the other stuff so the issues discussed here would be the only thing holding me back.

Anyway it was fun. Learned pulled bullets from load testing are worth recycling and it was good to knock more rust off the the comp next week.

Maybe I'm reading this wrong, if so please correct me.
The pulled bullets were more accurate than the fresh new bullets? The moly took 1 1/2" off the 1day group?
CW

 

[JCUtah]

Maybe I'm reading this wrong, if so please correct me.
The pulled bullets were more accurate than the fresh new bullets? The moly took 1 1/2" off the 1day group?
CW

Pulled was more accurate than some.fresh yep. Moly overall had more accurate groups yes.

 

[michaeljp65]

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."

I had some 204R ammo sitting in my safe for about 5 years. I sold the rifle that they were for. I then bought a new 204R same brand Tikka varmint. I tried that 5 year old ammo, it was still as accurate as the day they were loaded and tested.

 

[JFrank]

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!

I know this thread is quite old but this mirror’s my experience as well.
Jim

 

[Doom]

The springback issue may or may not come into play depending on the specifics of the interference but I agree that the most likely factor is likely to be the level of corrosion/oxidation due to air and contaminates. The degree to which these come into play are likely to very with how the brass is cleaned/prepped and stored.

 

[tennesseeshooter]

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]

Great post! Was there/has there been any further testing with annealed cases, if so, was the variance similar/larger/smaller?