Case Stretching Argentine

[CE310QT]

Could anyone give me some advice on acceptable levels of case-stretching (not for reloading purposes necessarily although info there is welcome) for an 1891 Argy Mauser?

I recently acquired a carbine for <$500. It headspaces OK, not great, but the bolt won't close (COMES REALLY CLOSE THO).

Anyway I took it shooting with some Prvi ammo to work it out and it shot just fine. I collected some cases and looked at em and there is definitely that tell-tale line of demarcation between the "fuzzy" zone near the shoulder and about 3/4 down the base above the case-head...just above the web.

I've had a case-head separation *kaboom* before in another rifle so I'm always a bit skittish.

Could someone give me some pointers for what to look for? I'm gonna shoot again and mic some cases next time. Some pictures of acceptable vs not acceptable would be great! I stopped loading my own stuff 5 years ago and prefer to just shoot commercial ammo.

 

[243winxb]

A comparator to measure head to datum of factory ammo before and after firing may give a clue on the amount of stretch. But may not be useful at all. New brass is very forgiving for 1 firing.

This factory ammo was fired in a rifle with excessive headspace.

For reloads, more then .010" is unsafe, with repeated loadings.

 

[Dog Soldier]

Case head separation or incipient separation is a sign of a serious problem. Read the link.

http://bulletin.accurateshooter.com...se-head-separation-how-to-detect-the-problem/

 

[boom boom]

CE310QT,
Take a paper clip and bend a small 90 degree hook at the end and straighten the rest Take a file and sharpen the edge of the small end . (Also works if you have a probe hook with a sharp 90 degree that will fit inside the case). Take the paper clip and drag the small edge lightly against the wall of the case. If you feel it catch about where the stretching is, the case will separate soon probably at that point. I would check each case as some factory brass varies a bit on spec.

The headspace comparator mentioned above works if you initially take the new brass and measure each case--mark them, and then measure the stretch after firing (Hornady formerly Stony Point). It does require a caliper to work. RCBS has something similar but never used it. Another is to take a chamber cast using something like cerrosafe which will also give you an idea of the condition of the throat and a measure of headspace.

For one rifle, it may be cheaper to simply take it to a reputable gunsmith for a check and take the brass with you rather than buy the tools above or mess with a chamber casting if you do not know what you are looking for. They generally have borescopes and can give you an idea about the overall condition of the rifle. A gunsmith may also need a few live rounds to testfire the rifle or they may charge you for a box of ammo.

You also did not mention whether you used a field gauge or no-go headspace gauge. To take headspace properly, the rifle's chamber and locking lugs along with the bolt need to be as clean as possible and the bolt needs to be stripped of extractor and the firing pin. Any debris such as old cosmolene, etc. can throw off a measurement of headspace. If it nearly closes on a field gauge, then your choices are to fire new brass only or have the barrel set back (assuming the receiver lugs are ok). Gunsmiths can also suggest other remedies which I don't really want to go into in this post. If the bolt is nearly closing on a no-go gauge, then you may have an overgenerous chamber which can also shorten brass life.

It is also possible, though I have never reloaded for the 7.65 Argy despite having a barrel for it somewhere, that you may have an issue where you have the wrong gauges--the 8mm for example is one that actually had the references changed on the shoulder angle in the 1930's. Thus, two differing reference headspace gauges for old 8mm versus new.

 

[CE310QT]

Tried the paper clip method. No apparent thin spot at all. Fired 20 rounds, none appear to show any signs of case stretching OTHER than that little shiny spot where I've seen thin spots in other cartridges...weird.

 

[mjsdwash]

Ive personally had about 8 case head seperations in three firarms, and can say everyone was inspected. None had an internal groove.