IVI Mil. Brass Failure

[Bill,SC]

Does anybody know anything about IVI  mil brass?  I was given several hundred rounds.  I don't have .308. Therefore, I re-sized to .243, trimmed to length, removed the primer crimp, annealed, then loaded 40gr H4350 behind 100gr BTSP.  On firing I noticed a crack 3/8" from the rim.  On the 6 shot I had complete separation.  This load is not hot or max.  Is this brass a bad brass?  Or, did I just get a bad lot?

Thanks

Bill

[fastchicken]

Actually, 40gr is Hodgon's max with a 100gr bullet

[Bill,SC]

You are right.  I was using a different reference which listed 43gr as max.  I backed off to 39gr to start and got accuracy at 40gr.  BUT, Hodgdon does list 40gr as max. 

However, that does not answer the question about IVI.  I use this load in other brass with no problem.  Is IVI trash?  Does anybody else have this problem with IVI?

[Old Syko]

The answer is in the fact that the IVI case capacity is much less than the commercial brass you've been using.  But you knew that already.  After putting all that work into brass that is readily available as commercial you did check capacity differences didn't you?

[mauser98us]

mil spec brass,sizing from 308 to 243 without neck reaming or out side turning,plus a max load. All these things are are tough on new brass,much les on brass that may have been fired in a semi auto and used an unknown number of times. Use caution my friend.

[Bill,SC]

Okay.  Neck turning or reaming I did not do.  That could have added to the problem--maybe. 

What is the capacity issue?  No, the capacity is not the exactly the same as commercial.  However, this load is only 80% capacity.  If it were a compressed load, maybe that would be a problem.  I don't understand why this could be part of the problem.

[parkergunshop]

Bill,

Military brass is designed to be heavy duty, thicker brass which means less powder capacity,  The same amount of powder in a case with less capacity raises pressures as does having tight necks which can cause the bullet to wait longer due to the case neck not being able to expand,  for higher pressures in the case before it moves down the barrel.   When you size brass down from .308 to .243 the case walls in the neck winds up thicker, the extra material  between .308 and .243 is squezed down into the neck walls, which requires a case neck turner be used to put the neck thickness back to  specifications.

You are lucky to have had the minor problems you have had.   If you use different makes of commercial brass, Remington, Federal, Winchester etc the capacity issue is also there but not as much as with military brass.   

A good neck turner is not cheap, you would be better served to discard the brass you have and get ready made .243 brass.

[Old Syko]

Military brass is designed to be heavy duty, thicker brass which means less powder capacity,

  If you use different makes of commercial brass, Remington, Federal, Winchester etc the capacity issue is also there but not as much as with military brass.

The quoted statements are old wives tales that just won't die.  Military brass may be either heavier or lighter than commercial.  I have a ton of examples that go both ways.  I have some LC 06 and LC 08 that are some of the lightest brass I've ever had.

Bill to readdress your issue, heavier brass means you have less capacity inside the case therefore you're pressures when using any given charge will be greatly increased.  In your case the pressures are increased to dangerous levels causing splits or separation.  You say you're only at 80% of case capacity when in reality if you're cases are heavy as I suspect, you may be at 120% of the pressure capacity for the case and this is what matters.  Percentage of case capacity by volume means nothing in this case.

Wherever you got this data from I'll bet does not show reformed 30 cal. IVI as what they used in testing.  The above explanation is one of the many possible reasons.  Decrease your charges in this brass by a good margin and try them over a chronograph and you'll understand real quick what the problem is.

[parkergunshop]

Old Syko,

You wrote:

The quoted statements are old wives tales that just won't die.  Military brass may be either heavier or lighter than commercial.  I have a ton of examples that go both ways.  I have some LC 06 and LC 08 that are some of the lightest brass I've ever had.

I beg to differ:

Just went to the shop and using my Pacific scale and the three types of .308 Winchester Brass I have on hand:

Military Lake City 72 Match brass weighs   184 grains
Federal Nickel Brass                     weighs   171 grains
Remington Brass                          weighs   173 grains

Lake city is 7.6 percent heavier than Federal and 6.4 percent heavier than Remington brass

In this case the old wives tale is true.   Lake city match is the only type of military brass I care to salvage and then I would only use it in the original bore size.

The thickness of the brass at the neck was the same for both the Federal and Lake City.

Six and seven percent heavier is enough to make a difference with maximum loads, much less having a tight neck from sizing down from .308 to .243.

[Old Syko]

Differ if you like but it is an old wives tale.  Even in your own post you used 39 year old LC brass rather than something more current and don't state how old your commercial brass is because you have no way of knowing date of manufacture.  I have a bunch of LC 68 5.56 that I will not load due to limited capacity compared to newer brass from the same manufacturer.  I also have some commercial RP 308 brass that is heavier than any LC of the last 10 years. 

As I said, it is an old wives tale that just won't die to assume all Mil brass is heavier than commercial.  With current manufacture brass (less than 10 years old) there is no more difference between military and commercial than there is from lot to lot commercial only.

Bill, so there's no confusion, IVI has always had a reputation of being quite heavy and heavy brass causes high pressures with the same charge levels.   

[yooper77]

Does anybody know anything about IVI  mil brass?  I was given several hundred rounds.  I don't have .308. Therefore, I re-sized to .243, trimmed to length, removed the primer crimp, annealed, then loaded 40gr H4350 behind 100gr BTSP.  On firing I noticed a crack 3/8" from the rim.  On the 6 shot I had complete separation.  This load is not hot or max.  Is this brass a bad brass?  Or, did I just get a bad lot?

Thanks

Bill

Hard to answer with an unknown history of your IVI military brass. It could be once fired or 6 times fired or more who knows. Cracked and separated case heads could be from over working and/or headspacing issues.

You did start out with an over maximum load for military brass and yes not neck turning will raise pressures depending on your chamber specs.

I suggest reducing your maximum load (using the military brass 3% rule) using data.hodgdon.com as the primary source. Turn the necks to tolerance, anneal and try again.

yooper77

[huntducks]

#1 with the cost of 243 brass being as cheap as any brass gets I would not waste the time or effort on some unknown military brass for all the reasons mentioned above.

The way You resized the brass could have caused a headspace issue (dies not adjusted right) most of the time that I have seen case heads crack or seperate is from headspace issue.

How did you anneal it?

[Bill,SC]

huntsducks:

Anneal: Torch, dark room, rotating brass in flame until begins to turn, drop in water.