Re: How many times can a case be reloaded?
As indicated by others case life depends on a variety of things. With thoughtful applications and getting the right equipment case life can go out the roof. For instance I have a 30.06 LC Match case I have loaded 157 times and I see now reason why it won't exceed 200 loadings.
The best combination for long case life I have found is in front locker bolt rifles, i.e. Mod 70 Win, Rem 700, M1903 and variants etc etc.
Brass deteriorates from being worked and it hardens every time it is moved and the more it moves the harder it gets. Round is fired, brass moves out, round is resized brass moves in, round is fired brass moves out and first thing you know you get case separation, case stretch etc. just like LD says.
How is this prevented or minimized? A custom made chamber reamer is the first course of action.
Lets take my 30.06 target rifles for instance. Factory chambers are cut at .471 to .473 range as measured .200" up from the rim. I have seen and owned rifles that deliver fired cases at .475 which is way out of SAAMI guidelines and when found is corrected ASAP. New commercial and military match 30.06 measures .465" at this datum so best case is you have your cases expanding .006+.
Now imagine you have a custom chamber reamer and you have a barrel with a chamber dimension of .467" so the new case expands .002 and springs back. As it turns out one of my 30.06 reamers is .467 and fired cases measure .4652" and .4653. Assuming you have a true FL size die, the sized case will only move .0002/.0003 on resizing. OK that takes care of the base dimension, what about the neck.
The neck on the particular reamer is .437. Loaded cases are .434 to .435. Fired cases after spring back barely accept a bullet with interference.
Stress relieving the neck is THE KEY here. One will notice LC/FA Match and other NATO cartridges exhibit a light blue tint equally distributed 360 degrees around the neck. As the case goes through the draws they work harden and they are stress relieved at neck/shoulder prior to loading. The reason the blue tint is not seen on commercial applications is it is polished prior to loading.
There has been reams written about sitting cases in a pan of water up to the necks and heating hell out of them with propane torches and knocking them over. Think about it, how can one deliver even heat to a case sitting in a pan of water? Obviously you can't so if you are only heating one side at a time you are not doing your case justice.
Would it be logical to assume the way to do such is do it the same way the ammo plants do them? Obviously this is the logical approach and from a production stand point the way to go.
Ammo production these days is done two ways, the old production lines and SCAMP lines. SCAMP to my knowledge is only at Lake City AAP and the industry is still doing it the old fashioned way.
On the history channel there is a program about Winchester ammo production and there is a quick shot of the cases being stress relieved which is achieved by the cases being run down a line between about six jets of natural gas aimed at below the shoulder as they rotate through the flames and come out the end and drop into a buggy. THEY ARE NOT COOLED BY DUMPING THEM IN WATER ! ! ! !
Obviously the reloader doesn't have access to such but you can easily duplicate the procedure just as well at home. If you have a lathe or a friend with one you can simply get a piece of round stock 3/4" diameter and four inches long. (We are talking 308/30.06 type rounds here.)
Chuck in it lathe and turn one end to .375 about one inch long. On the other drill a half inch hole about 1 3/4" deep.
Chuck in variable speed hand drill and set rpm to about 200 after chucking the .375 end in drill. Set your propane torch up with a INNER BLUE sharp point flame about 1 inch long. Place a sized case in the 1/2 inch hole and it starts spinning. Aim the sharp blue inner flame to just contact the case about 1/4" below the shoulder.
WATCH THE BASE OF THE CASE NECK CLOSELY AND JUST AS SOON AS YOU SEE THE BASE START TO CHANGE COLOR AIM HOLDER AT A LARGE TOWEL AND POINT DOWN AND THE CASE WILL DROP FREE ON THE TOWEL TO COOL.
This takes five to six seconds of time in flame for 308/30.06. This case holder will hold 7.5 Swiss, 270, 280, 260, 308, 243, 7/08 and a number of others.
Examination of the case on the towel should reveal a light blue even tent all the way around the neck/shoulder. Note you aim small blue flame at case BELOW the shoulder and the heat will run to to the neck. Placing the small blue flame on the neck will quickly turn it red and you will ruin the case. After it hits towel you want it light blue. Dark blue you have had it in too long.
This is best done with clean brass. I clean mine by using stainless steel pin media tumbled in a 15 lb capacity Thumler's Tumbler.
Five pounds of media, 1 quart of cases, one gallon of hot tap water and 2 ounces of Ivory dishwashing detergent will make them look absolutely brand new! ! ! ! It will clean all carbon out of primer pockets and inside of cases.
I tumble them 12 hours.
Now there are those that are thinking I don't want to get a custom reamer etc. There is another way to enhance case life. You get dies that only size your fired case at the base .001 to .002". I have four sets of 30.06 dies. One sizes at .465", another at .466", next at .468" and last one at .471. Thusly on factory barrels I have not replaced I simply select the die that sizes the least amount as obviously a case fired in a .473 chamber need not be sized smaller than .471" so there you have it.
Get a good set of dial calipers and haul to gun shows and measure the inside of any potential die purchases to determine how much they will size. Don't just rely on the term Small Base die. A true FL die will take a medium 308 case or 30.06 family down to .465. In reality my .465,
.466 and .468 dies are standard factory production.
The name of the game is just to size the minimum amount needed.
Bear in mind some cases have "soft heads" due to a shortcut in production that does not result in hardened cases.
In the 308/7.62 family any NATO spec round (w/ NATO STAMP ) meets the hardness gradient requirements. Commercial cases to my knowledge are not made to the NATO requirements. Thus will exhibit severely shortened case life as indicated by LD's testing.
The above is only indicated for bolt guns in similar calibers. Semi autos are a different game, handguns are a vastly different game and case life is severely cut with these unfortunately.
My favorite brass of all time is DWM but alas I can't afford it. Next in commercial brass is IMI. It is offshore and cases are made to milspec in 308. On shore my favorite brass for long life is LC and FA. There is one year of FA 30.06 Match brass that is not good. 1957 Match had soft heads like commercial brass so be forewarned.
What does soft heads do for you? The primer pocket opens up, primer is not held snugly allowing gas leakage around edge and cutting into bolt face.
Hope this makes sense to many as being set up as me and my friends that have similar set ups == one can use the same brass for years. For instance I had 300 cases I ran in the same 30.06 rifle shooting HP matches for ten years. Never had a split neck, never had a head separation and after cleaning it up I am still using it. I segregated cases for rapid fire and long range. LR is half neck sized.
Unfortunately I only learned of the stainless steel media about 18 months back and first 45 years of reloading were a waste haha.