Why these .30-30 case neck splits?

[claybob86]

These .30-30 cases both split on their third firing. 170 gr. JSP over 31 gr. W748. The one on the left is Winchester, the other is Remington. 1 out of 40 Winchester cases split like that. So far 7 out of the first 20 of a batch of 60 Remington cases split like that. All of the cases get sooty back to the shoulder as shown in the photo. Any comments or suggestions?

[Trailboss]

claybob86, I don't think it's your powder type or charge weight. 31 grains of W748 is a fine and accurate load for a lever action when pushing a 170 grain jacketed bullet. Have you checked bullet diameter with a micrometer yet? Just to be sure. What does the bore look like?

[flatnose]

Measure the inside diameter of the necks. If they are over .311'', then you may have an oversized chamber neck. This would cause overworking of the brass, and the splitting and powder marks on the necks. Anneal the necks.
Take the fired brass and with your thumb on the back of the neck, push the case mouth onto a flat surface at an angle of 45deg. You should be able to put a flat on the case mouth. If the brass does not distort, it needs annealing.
Check your resized brass, and make sure the dies are not scoring the brass cases upon resizing.

[Pisgah]

.30-30 chambers in general, and levergun chambers in particular, tend to be a bit generous. Depending on the rifle, full-length sizing may be necessary, but it can very quickly work-harden the brass. You could try neck-sizing only, and if that doesn't work then annealing your cases may help.

[Griff]

My most accurate .30-30 does the exact same thing. Generous neck & shoulder area... But, it has a short throat; outside of setting barrel back a turn and re-cutting the chamber, do like I do, ... live with it. (The reason I just live with mine is that I have several .30-30s and don't want to just load ammo for this one rifle). Like yours, I can fire a piece of brass in this gun just 3 times before it's ready for the scrap brass bin.

If you have only the one .30-30, get a neck sizing die and ream it to match your chamber neck. Determine what diameter your bullets need to be to get neck tension and size bullets accordingly. Then work up loads based on that combo...

My rifle that does that wears an aftermarket barrel. I was told when I had it installed the chamber was very rough, and should have them trim the barrel and recut the chamber... I didn't wanna go to that expense, and left it alone... 28 years later... still shoots better than I can see... actually, now, it can shoot MUCH better than I can see! I buy once fired brass, load it 3 times, and toss it. It's probably seen more rounds thru it than the rest of my 30-30s put together.

[claybob86]

claybob86, I don't think it's your powder type or charge weight. 31 grains of W748 is a fine and accurate load for a lever action when pushing a 170 grain jacketed bullet. Have you checked bullet diameter with a micrometer yet? Just to be sure. What does the bore look like?

Bullet diameter is .308, bore is excellent.

Measure the inside diameter of the necks. If they are over .311'', then you may have an oversized chamber neck. This would cause overworking of the brass, and the splitting and powder marks on the necks. Anneal the necks.
Take the fired brass and with your thumb on the back of the neck, push the case mouth onto a flat surface at an angle of 45deg. You should be able to put a flat on the case mouth. If the brass does not distort, it needs annealing.
Check your resized brass, and make sure the dies are not scoring the brass cases upon resizing.

The ID of the necks measures from .307 to .309, but there might be a bit of crimp left throwing that measurement off. A dial caliper is all I have to measure that with. Outside neck diameters are .330 - .331. I can slip a .308 bullet into some of the cases with finger pressure, some are tighter. Easy to put a flat on the case mouth with thumb pressure.

.30-30 chambers in general, and levergun chambers in particular, tend to be a bit generous. Depending on the rifle, full-length sizing may be necessary, but it can very quickly work-harden the brass. You could try neck-sizing only, and if that doesn't work then annealing your cases may help.

My most accurate .30-30 does the exact same thing. Generous neck & shoulder area... But, it has a short throat; outside of setting barrel back a turn and re-cutting the chamber, do like I do, ... live with it. (The reason I just live with mine is that I have several .30-30s and don't want to just load ammo for this one rifle). Like yours, I can fire a piece of brass in this gun just 3 times before it's ready for the scrap brass bin.

If you have only the one .30-30, get a neck sizing die and ream it to match your chamber neck. Determine what diameter your bullets need to be to get neck tension and size bullets accordingly. Then work up loads based on that combo...

My rifle that does that wears an aftermarket barrel. I was told when I had it installed the chamber was very rough, and should have them trim the barrel and recut the chamber... I didn't wanna go to that expense, and left it alone... 28 years later... still shoots better than I can see... actually, now, it can shoot MUCH better than I can see! I buy once fired brass, load it 3 times, and toss it. It's probably seen more rounds thru it than the rest of my 30-30s put together.

Might try a neck sizer, otherwise just live with it. Rifle shoots fine.

Thanks for all the help, guys!

[flatnose]

.309'' neck id sounds fine. .307 would be borderline as a very tight neck to chamber clearance, and maybe even dangerous.
Anneal the necks, then size 2/3 or 3/4 of the neck with your full length die adjusted accordingly, and see if it will chamber. If not you will have to size more and bump the necks back a couple of thou. Make sure your expander plug, and die are not scoring the brass when resizing.
You should be able to at least treble your brass life. I no longer rate Winchester brass as a quality product, but its surprising you have similar results with 2 different brands.

[Shasta]

Try annealing, it likely will extend case life. It can be done inexpensively by using a suitable deep 3/8" drive socket rotated in a drill over a propane torch flame. Just make sure the neck and shoulder area extend above the mouth of the socket. Heat the brass neck to a very dull red, then dump and allow to air cool.

Shasta

[earlmck]

I anneal after I make Improved Zippers out of 30/30 brass because the new shoulder area had to expand quite a lot because it was previously "neck" area. You need to do the same for your Improved 30/30 for the same reason. Our you're gonna get more splits like in your pictures.

[olskool]

fatigue, just plain worn out.

[J Miller]

claybob86,

From the pics you posted I'd say your rifle has a chamber problem.

Having said that I'll elaborate a bit. I've owned over 14 Win 94 30-30s and until the 1950 carbine I have now, none of them split case necks to any degree. My current 1950 carbine will split the case necks like yours does on factory loads and reloads.
I have less than 1oo rounds through it and it has split well over 75% of the cases I've fired.
This one 94 carbine has split more cases by itself, than all the rest of the 94s I've owned combined.
Here is the threads I did that has pictures of the case mouth splits:
viewtopic.php?f=1&t=31050&hilit=Cerrosafe+Follies
Click on the first link in this thread and it will take you to picks of my split cases and my measurements while attempting to diagnose it.

If it were only reloads I might think brass fatigue, but not when it also splits factory cases.
I also have brass I bought as loaded ammo back in the 1960s that has been loaded over 20 times and it's still good.
So, not fatigued brass, a bad chamber.

I am going to rebarrel my 1950 as it has a short chamber mouth as well and wont chamber cast or plated bullets. I would suggest you take yours to a good gunsmith, if you can find one, and have it checked out.

Joe

[claybob86]

Joe, the cases have never split before their third firing.

Thanks, and I hope you're healing well from your surgery!

[earlmck]

I'm with Joe on the chamber problem idea. When I made my earlier post I thought this was some sort of "improved" chamber but when I tried to get some dimensions off the photo it seems too close to a regular 30/30 to be any intentional "improvement". I'm guessing that like Joe's chamber on his problem rifle, this one is just extra generous in the shoulder area. If you are full-length sizing you are setting back the shoulder area each time you size and this soon sets up the shoulder splits. I have a couple of 30/30's and over the years have lost a modest number of cases to neck splits but never to shoulder splits. I've sure had some shoulder splits on my Improved Zipper cases made from 30/30's, if I don't get a good anneal on them both before and after forming.

You might get away with just adjusting the size die so that it doesn't quite touch the shoulder of the fired case when re-sizing and see if this doesn't vastly improve your brass life situation. But I'd be thinking of getting talented at the annealing process, which has given me problems over the years since it is easy to not get hot enough to anneal and also easy to get too hot and have the whole shoulder area too soft. The temp-e-lac crayons (not sure of the spelling on that) that melt at the different temperatures help me out here -- you only have to use them enough to get educated on your particular brass and your heat source as to how much time in the flame is right.

[claybob86]

I see where the brass is getting overworked at the base of the neck where it meets the shoulder, which is where the cracks are.





I'll try some of the above suggestions and see how it goes.

[marlinman93]

Before doing anything the first thing I'd do is a chamber cast. But I do a chamber cast on every gun I buy before I start loading for it, just so I can see all the details of the gun's chamber and get my brass and specs correct for the gun. A chamber cast might tell you things you can't see any other way.
The load of 31.0 grains of 748 is OK, but my manual shows it at the minimum charge for that bullet weight and that powder. Once you've done the chamber cast and see it's all OK, you might bump it up a grain and see if it changes any splitting issues?

[Chuck 100 yd]

Before doing anything the first thing I'd do is a chamber cast. But I do a chamber cast on every gun I buy before I start loading for it, just so I can see all the details of the gun's chamber and get my brass and specs correct for the gun. A chamber cast might tell you things you can't see any other way.
The load of 31.0 grains of 748 is OK, but my manual shows it at the minimum charge for that bullet weight and that powder. Once you've done the chamber cast and see it's all OK, you might bump it up a grain and see if it changes any splitting issues?

^^^ +1 ^^^ From the picture,I would guess that the chambers shoulder area is not where it should be. Setting the shoulder back to SAAMI spec is causing that area to be overworked and fails. I would back the die out about 1/16" and try again. If you have a case length comparitor gauge set ( Hornady) you could check this easily.
I bet your fired brass would not even come close to chambering in a normal .30-30 rifle chamber.
Not that you need to have the barrel replaced or set back and rechambered. You just need to shoot fireformed brass and not over size the brass when reloading. I would size the minimum amount possible and still get a good bullet friction fit (bullet pull).
Treat it like a wildcat. You may have to anneal the brass first and seat bullets out enough th give zero headspace on that first fireform shot. A fun project !

[Merle]

Before doing anything the first thing I'd do is a chamber cast. But I do a chamber cast on every gun I buy before I start loading for it, just so I can see all the details of the gun's chamber and get my brass and specs correct for the gun. A chamber cast might tell you things you can't see any other way.
The load of 31.0 grains of 748 is OK, but my manual shows it at the minimum charge for that bullet weight and that powder. Once you've done the chamber cast and see it's all OK, you might bump it up a grain and see if it changes any splitting issues?

^^^ +1 ^^^ From the picture,I would guess that the chambers shoulder area is not where it should be. Setting the shoulder back to SAAMI spec is causing that area to be overworked and fails. I would back the die out about 1/16" and try again. If you have a case length comparitor gauge set ( Hornady) you could check this easily.
I bet your fired brass would not even come close to chambering in a normal .30-30 rifle chamber.
Not that you need to have the barrel replaced or set back and rechambered. You just need to shoot fireformed brass and not over size the brass when reloading. I would size the minimum amount possible and still get a good bullet friction fit (bullet pull).
Treat it like a wildcat. You may have to anneal the brass first and seat bullets out enough th give zero headspace on that first fireform shot. A fun project !

For any cartridge I never start with the sizing die bumping the shell holder - sometimes this will cause trouble.
Your brass looks like it was fired in an "improved" chamber, so the above is a very good explanation of what is going on.
Compare the neck of an unfired case to one that was fired - and you'll see the problem.