30-30...Reasons for split casings??

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oneone

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Just got back from the range with a new-to-me Marlin 336.

I fired 30 rounds, and four of them are pictured below.
These are the only ones that split. I have never had this happen before.
They all grouped as normally as all the others.
What are some possible causes for this happening?
Anyone else have this happen?
(Factory Winchester 170gn.)

IMG_0621.jpg
 
oneone said:
Just got back from the range with a new-to-me Marlin 336.

I fired 30 rounds, and four of them are pictured below.
These are the only ones that split. I have never had this happen before.
They all grouped as normally as all the others.
What are some possible causes for this happening?
Anyone else have this happen?
(Factory Winchester 170gn.)

IMG_0621.jpg
Click to expand...

It looks to me like a case of brittle brass and something I wouldn't expect from new ammo,assuming this is fresh stuff that you started with.Awhile ago,my son and I were shooting at a large gravel pit up north of us and we came across 20 or so 303 British empties that appeared to be fresh fired factory ammo with Winchester headstamp on them and several of them had neck splits just like your 30-30 cases.Maybe they are having some quality control issues?
 
+1 RedRabbits

Do the other casings looked stretched even though they didn't split?

You mentioned that it was a "new-to-me" rifle.
Do you know how old (what year) the rifle is, and did the previous owner make any modifications that you are aware of?
I've seen posts on some forums where people were determined to polish their actions and the chamber.

I would take the rifle to a gunsmith and have them run a .30/30 headspace gauge on it for go/no-go, and check the chamber, just to be safe.
 
If the primer is protruding from the case it is likely a headspace problem. I have also noticed a lot of new Winchester brass lately has some in the bag that are cracked or near cracked from new, not sure about their loaded ammo. Is the ammo old ?
 
Yikes! Last time I saw 30/30 brass like that was shooting some vintage imperial crap.
X2 on trying another brand.

Did you keep the box? IIRC there is a lot number one one of the flaps, I'd be contacting the ammo company about this.
 
I had this happen with a .30/30 a while back with a box of federal classic.It happened to two casings.I sent them to federal and they sent me a voucher for two free boxes.They blamed it on poor brass and a chemical reaction of some sort(can't remeber exactly,it's been a while).I've put many rounds of different manufacture through her since and never had it happen again.It is a marlin 336 as well.
 
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deegee said:
+1 RedRabbits


I would take the rifle to a gunsmith and have them run a .30/30 headspace gauge on it for go/no-go, and check the chamber, just to be safe.
Click to expand...

30-30 headspaces on the rim so it won't tell you anything about the shoulder region, I don't believe. I know the belted mag gauges don't have any body or shoulder and I assume the rimmed headspace gauges do not either. It really looks to me like someone polished this chamber almost to an improved but rounded. It doesn't look right to me at all, not enough taper and the shoulder looks too steep.
 
Some of the new ####ty Winchester brass.

The quality of Winchester's brass the last few years makes it appear they are sourcing from NORINCO. ;)
 
The second one has two vertical splits with a crack joining them.
The last one looks like it is trying to do the same thing.
Next time out, mark the case with a marker and position it and the following
round in the same location to determine if it's doing this in the same spot in
the chamber.
Then examine the neck area there.
 
A headspace issue wouldn't cause longitudinal cracks at the shoulder. X2 on the trying of another brand of ammo.
 
ok, thanks for all the replies.

I threw the damaged brass in the trash at the range, but as far as I remember the primers looked normal (like all the other fired cases).

I still have the box, and I bought this box about a year and a half ago.

I will post pics of a few casings that are not cracked.

Thanks again.
 
The shoulders look too rounded out to me.
Compare one of the empty casings to a new round if you have one left.

IMHO this is more than likely caused by one of the things I mentioned in my first post:
1) Someone decided to polish the chamber (possibly along with the action) and in doing so they rounded it out.
2) Correct me if I'm wrong, but afaik if there is excessive headspace (the gap for the rim with 30-30) the casing doesn't shoulder fully in the chamber and stretches, because the round is sitting further back at the bolt. I've not seen casings from an excessive headspace 30-30 rifle so I am not familiar with what they would look like.

You could compare these casings to another brand/box and see what you get.
I would just be careful of excessive fouling in the chamber from the cracked casings.
 
when in doubt.... do a cast of the chamber. There are lots of online faq's for this... and some great youtube vids. I think I have even seen cerrosafe listed on here..

the shoulders of the fired stuff do look a little round, but looks and photos can be deceiving. I had 4 pieces of .303 brit do it on some new old stock Winchester ammo. I shot 3 boxes that day and only those 4 split. I say it was the brass being brittle.

You can also put some calipers around it, and measure it compared to the readily available case specs. It should not be excessively larger. I am no expert, so help me out you old hands.. I am guessin no more than a few thousands larger after being fired, as comapred to new.

Case stretch would be indicative of trouble, as well as a bulge that may be apparent if rolled across a flat surface such as glass. Look inside the case with a little light and check for stretch near the base while you are at it (which would also probably have a matching ring of some degree on the outside also). Some use an 'L' shaped probe to scrape the inside to check for this stretch ring, feeling for the telltale depression.

This is all academic of course, as your problem seems to be the shoulder (as someone suggested, some ham-handed novice gunsmith may have polished it out), or perhaps brass quality. Shoot some more rounds from a different manufacturer or production year if you can. See what happens.

In any case, good luck. :)
 
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