reloading for accuracy questions

[Steve Sheasly]

I replied to another member in this string:

forgot to paste --It makes sense to me to full size for consistency if nothing else. Just neck sizing would put different stresses in the top sized brass while leaving the un-sized brass with different stresses. There is science to back this up. Flow stress can be defined as the instantaneous value of stress required to continue plastically deforming the material - to keep the metal flowing. If you stop, you will create inconsistency's in the material-- in this case the brass. You can actually set up for premature failure with stress risers in the case that will eliminate the reason for only neck sizing in the first place. I have to agree full sizing must create a more consistent case.

 

[Barrelnut]

You can actually set up for premature failure with stress risers in the case that will eliminate the reason for only neck sizing in the first place. I have to agree full sizing must create a more consistent case.

Never seen this happen. This is not at all the reason a shooter usually experiences case failure. IMO, you do not understand the basics of what is happening to a case when fired in a chamber and where and why it weakens. Still think you would benefit from reading a reloading manual that explains the firing process completely and it's effect on a case.

 

[Steve Sheasly]

Never seen this happen. This is not at all the reason a shooter usually experiences case failure. IMO, you do not understand the basics of what is happening to a case when fired in a chamber and where and why it weakens. Still think you would benefit from reading a reloading manual that explains the firing process completely and it's effect on a case.

Do you know that I have not read the manual or manuals? I am new to long range reloading not to reloading. I have reloaded thousands of rounds.
I am simply stating facts. Flow stress is real and may be applied to re-sizing IMO. I am not saying a failure will occur I am saying the potential is there. I have learned a lot from these threads and being introduced to some great folks. Years and years of experience you cannot find in books.
I have not developed an opinion on all things but for me full length sizing makes perfect sense. I do understand a little bit about metals having worked for ITT and Precision Cast Parts in the past and their respective foundries. What happens inside the breach is fairly obvious. What happens inside the case may not be.

 

[Barrelnut]

Steve,
You made this comment in your first post.

Once this is done I understand that the case should be bumped back .002 or .003 so the fluctuations in ambient temperature will allow the chambering of the cartridge and the projectile should be seated about .005 to .015 (which ever is more accurate for my rifle with load development).

Is this correct?

This question about bumping back the case .002 or so to account for fluctuations in ambient temp, sort of gave me the impression that you were missing something about why bumping back .002 is actually done. It is not done just to allow a perfect fit for long range accuracy and is really not done to account for ambient temperature. It is mainly done to prolong the life of the case and can have some safety implications.

 

[Steve Sheasly]

Steve,
You made this comment in your first post.


This question about bumping back the case .002 or so to account for fluctuations in ambient temp, sort of gave me the impression that you were missing something about why bumping back .002 is actually done. It is not done just to allow a perfect fit for long range accuracy and is really not done to account for ambient temperature. It is mainly done to prolong the life of the case and can have some safety implications.

thanks, In my question, I was wondering how ambient temperature would affect the fit. Coefficient of thermal expansion/contraction are different for different alloys. But maybe not so much that the delta T will affect fit. (I have been reading a lot of articles (while visiting our grandchildren in Texas) and am not at my bench or range. Probably a good thing. )
But I am still unclear after all the reading why exactly the .001 or .002 could not be cut down to .0005 to create greater consistencies. I am going to test this unless someone can tell me that it will create pressure spikes (this does not make sense if the CBTO does not jam the projectile) COAL will vary but the CBTO should be constant. The case expansion will work harden the case which can be alleviated with annealing but might be avoided for a duration if the case expansion is cut to a minimum and the results of impact point should be enhanced?

 

[desertcj]

Caprb, that Brux video is correct.
Amen!!!!!!!
Every word he said is true.
Everyone who neck sizes only gets what they deserve.

I'm not going to say that the full length guys are wrong, but if neck sizing is producing consistent 1/2 moa groups for me, and that's what I deserve? Yes please!

 

[bigngreen]

Are you an engineer?

 

[Canhunter35]

IMO reloading accuracy is best achieved by consistent full length resizing with repeatable step by step procedure. It's not hard. Just pay attention to detail and do it the same every time.
Good accuracy is achieved with a good load. Sometimes it takes experimenting with different powders/bullets, sometimes you stumble onto it instantly.

 

[Steve Sheasly]

Are you an engineer?

retired, now I cant even spell it.

 

[Steve Sheasly]

IMO reloading accuracy is best achieved by consistent full length resizing with repeatable step by step procedure. It's not hard. Just pay attention to detail and do it the same every time.
Good accuracy is achieved with a good load. Sometimes it takes experimenting with different powders/bullets, sometimes you stumble onto it instantly.

instantly would be nice!

 

[Canhunter35]

instantly would be nice!

Some cartridges are definitely easier...308, 6.5 creed are really easy to get accurate. I've read that thr 338lm is also an inherently accurate cartridge

 

[Steve Sheasly]

I traded a DW .445 Supermag for this supposedly one hole gun. (depending on who is holding it and what is meant by one hole).
I think the .338 LM is a good LR round for sure. I am going to move very slowly and keep good records. I want to do things others are not doing to get reliable consistency in my manufactured rounds. I take things to the quantum level so to speak. I intend to have a lot of fun and hopefully break a few records in the process. This is just a start.

 

[LaHunter]

thanks, In my question, I was wondering how ambient temperature would affect the fit. Coefficient of thermal expansion/contraction are different for different alloys. But maybe not so much that the delta T will affect fit. (I have been reading a lot of articles (while visiting our grandchildren in Texas) and am not at my bench or range. Probably a good thing. )
But I am still unclear after all the reading why exactly the .001 or .002 could not be cut down to .0005 to create greater consistencies. I am going to test this unless someone can tell me that it will create pressure spikes (this does not make sense if the CBTO does not jam the projectile) COAL will vary but the CBTO should be constant. The case expansion will work harden the case which can be alleviated with annealing but might be avoided for a duration if the case expansion is cut to a minimum and the results of impact point should be enhanced?

In my opinion, reasons that bumping the shoulder back .0005" is not a standard practice are: 1) the instruments / tools used in reloading are not precise enough for that many decimal places with an acceptable % error, 2) any powder residue or tiny amount of dust or anything will cause a bind in the chamber, 3) the gain that you MAY achieve isn't worth the effort. Are you a good enough shooter to see a .1 MOA improvement in accuracy? No need to re invent the wheel or over think reloading.

 

[Snyper708]

I do understand a little bit about metals having worked for ITT and Precision Cast Parts in the past and their respective foundries.

What type of furnaces did you use?