reloading for accuracy questions

[WildRose]

Ok, here goes my ignorance -- ignorance is not stupidity. Stupid cant be fixed with knowledge or experiance, but ignorance can.

Broz used Redding precision shell holders to bump the shoulder back .004 to get zero then .006 bump for the perfect fit for his rifle. He explains that it is fired brass and that you do not want to feel any friction on the closing of the bolt. I agree with him that this would give you a pretty good zero.

But if the bolt will close on a fired brass case, it is fire formed to the chamber so why not just reload and shoot the once fired brass as it is? I do not think you can get a more perfect fit than this-------I am guessing that it is because from experience the brass will stick into the chamber right? If this is the case then why not bump it back one thousandth at a time and fire the rounds until they do not stick? Wouldn't this be the best fit possible? I know I would have to knock the brass out a few times but it should not do any damage to the gun.
But if the idea is to get the cartridge and chamber to fit perfectly as possible this should do it.

After a couple of firings it will grow enough to cause you some serious headspace issues and if you aren't at a minimum trimming your brass after every couple of firings you run a high risk of the neck flowing far enough forward to put a hard crimp on the bullet creating dangerously high pressures.

 

[Steve Sheasly]

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.

now that makes perfect sense to me. You are the first one to answer the question. Sometimes the obvious is not so obvious to me. Thanks

 

[Steve Sheasly]

What type of furnaces did you use?

induction

 

[Snyper708]

induction

Were any of them from Ajax Magnethermic?
I used to work for them long ago, in a galaxy far away...

 

[Steve Sheasly]

What type of furnaces did you use?

induction

What type of furnaces did you use?

Way off of the subject but interesting: Induction Vacuum. We did exotic metals at PC -- TIO2 mainly, Inconel, 400 series stainless. Made parts for the military and jet engines. Sometimes we hot topped, this keeps the material molten so the liquefied metals can flow into risers and gates. Mostly investment casting.

For ITT we used sand cast and cupola style furnaces, gas fired pump casting mainly.

 

[Steve Sheasly]

yes that is the style we use

Were any of them from Ajax Magnethermic?
I used to work for them long ago, in a galaxy far away...[/QUOTE
yes that is the style we used for Rolls Royce engine mounts for jet engines. This was in the 1970-80s. Maybe the same galaxy. The procedure is still the same but a lot of robots do the dangerous work now. Too bad because those were good paying jobs.

 

[Snyper708]

This was in the 1970-80s. Maybe the same galaxy.

I worked for them from 79-91.
I may have built some of those.
It's a small world sometimes.

Too bad because those were good paying jobs.

Yes they were, and I enjoyed doing it, plus the fact it was only 3 miles from my home.

We also made a lot of things for Olin/Winchester.

 

[Steve Sheasly]

I worked for them from 79-91.
I may have built some of those.
It's a small world sometimes.



Yes they were, and I enjoyed doing it, plus the fact it was only 3 miles from my home.

We also made a lot of things for Olin/Winchester.

I would like to get in touch with some of my old friends and one in particular. I may still have his email address -- He was a dr. of metallurgy I know he would be able to answer my brass questions. I am glad you jogged my memory. I will let you know what he has to say about the brass use in casings. Probably will not do a lot for accuracy but every bit of knowledge can be applied to the things we are passionate about --

 

[Steve Sheasly]

I would like to get in touch with some of my old friends and one in particular. I may still have his email address -- He was a dr. of metallurgy I know he would be able to answer my brass questions. I am glad you jogged my memory. I will let you know what he has to say about the brass use in casings. Probably will not do a lot for accuracy but every bit of knowledge can be applied to the things we are passionate about --

Sometimes we need to get off the subject to get back on it.

 

[WildRose]

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?

One reason brass is so popular for many applications is that it doesn't change much in volume with temperatures. You're not going to see enough difference in the temperature range that humans can survive to even measure without some extremely precise scientific tools.

 

[just country]

morning, Wildrose is totally right. I use Winchester brass if possible.
90% of the chambers on my rifles have a AI chambering. I've had
neck splits, and case ruptures. I inspect I my brass after every firing.
I always clean the necks.i try very hard to keep the maker and weight
of brass consistent. I use a dial caliber to measure case stretch. there
r lots of variables when reloading that a hand loader can follow.
I have my procedures. I gauge my reloading success by consistence of the
size of my groups after firing. I shoot standard and magnum calibers. be safe. GBOT TUM

 

[Buzzsaw]

You Tube is your friend. Whidden has some good vid's on their products

 

[358 Guy]

I outside neck turn just enough to make sure the neck is round and resize the case just enough for reliable chambering. (about 2 thousands clearance) I also believe that uniformity is the key to good accuracy. I cut my primer pockets to a uniform depth and chamfer the flash holes using tools available from Sinclair. My pet hunting rifle is a 300 Weatherby in a Weatherby Vangaurd SS 2. My bullet seating depth is limited by the magazine length. I'm shooting Barnes 168 gr. TTSX's under a load of 86 gr. of Reloader 22, Federal 215 primers, and Norma cases. This load produces groups of 3/8" to 5/8" at a velocity of 3300 fps. Good luck, and good shooting!

 

[jshepherd61]

If you are wanting to save brass wear

You are right I tend to overthink. The load is .338 LM. I am trying to understand how a reloaded cartridge will best fit in to the chamber. I would like the round to fit as perfectly in the chamber as possible without getting it stuck. I understand some jump is needed and load development will determine the best jump by trial and error. I want this brass to last as long as possible. It is close to $5 when I pull the trigger on factory

Thank you for the reply. It seems that the neck is crucial to accuracy for the reasons you have outlined and you have confirmed my thoughts. Seems like bullet jump and COAL are fairly easy to determine with the gauges on the market. I have not found much on the neck or the amount of free chamber needed for accuracy. I am just starting to research however and I am sure there are articles out there. Our ranch and home is in Pendleton Oregon.

and life of the brass! start just neck sizing, length trimming and anneal your case neck every four loads. You will see the accuracy you want by just neck sizing and making sure your neck tension is the same across loads and if just neck sizing you can't get a better fit in the chamber.