Can't stop breaking sizing dies !

[Florentoutang]

Hi everyone !

I got a problem when I reload my 300 norma magnum cartridges : I break my sizing dies.

I had a forster full lenght sizing die, who broke rapidly (less than 200 brass resized). I thought it was a default of the tool.
Where I leave, my rifle is the only one chambered in 300 norma magnum, so getting a new one is loooooong.
Lucky I am, the friend who sold me the gun had a redding die set (body die + neck sizing with bushings). I love those dies !

But 2 hours ago, I sized some brass, and the redding body die broke in the exact same way than the forster, so it can not be the tool the problem...
Now, I have to order another die, and wait for the shipping with covid-19...

I did not forced on the lever of the press so much, and I use imperial wax, who seems to be very effective.

I need to solve this problem, so I think about differents possible causes, but I am not sure of that...

- Problem with the shell holder ? Maybe this is not well made...

- Problem with the press : I use a basic lee press, and maybe the screw thread who maintains the tool is not enough deep to support pressure of the die when sizing brass...

- Problem with overpressures :
When I fire, it's difficult to extract the brass. It seems to be not so dramatic, and I have no marks on the bottom of the brass or on the primer. The lower section of the brass becomes large, but I have not to force on the lever of the press to resize them.
Load info :
Norma brass, federal GM215M primers, Hdy 225grs eld-m, ADI AR2225, 85,6 grs powder, 920m/s speed of the projectile.
I shot in the same config with 91 grs of 2217 powder withoud problems, and during developping load, I reached 950m/s with 89,6 grs of 2225, without overpressure signs.

- Problem with the chamber :
The friend who mounted the rifle (custom based on stiller action) chambered himself the tube with a friend I know. Job was made with go, no go and fields gauges, and this was not their first chamber, so i really think I can trust them with this job.

If you can help me, this would be great !

 

[Powder_Burns]

From the thumbnails it almost looks like the dies are bending and splitting. From that much I am wondering if you are using a C shaped press and putting too much force on it during sizing causing it to flex and crack the dies, or if the ram is worn out and the resulting misalignment is causing the dies to flex. Measure your fired cases and resized cases if you have any and compare dimensions. Check case web and shoulder diameter for comparison, then see if you can compare that to the chamber specs. I still think the issue is with your press though.

 

[Evlshnngns]

You need to measure new brass compared to ounce or twice fired at .200" above the base. That norma is thinning out a 7/8 thread die to the max, but I would blame your chamber before the die.

 

[Powder_Burns]

When you set up your dies, are you over-camming the dies against the shell plate or just touching it?

 

[Florentoutang]

When you set up your dies, are you over-camming the dies against the shell plate or just touching it?

Approx 1/4 of a turn after contact with the shell holder

 

[Powder_Burns]

Maybe back that off a 1/4 turn. Screw the die in with the ram fully raised until it makes contact and start there. Don’t overcam it too much.

 

[lash]

I have never seen that type of die failure before. I’m interested in what the cause is as well.

 

[Florentoutang]

You need to measure new brass compared to ounce or twice fired at .200" above the base. That norma is thinning out a 7/8 thread die to the max, but I would blame your chamber before the die.

Here's pics of a brass fired and a brass resized entering in another chamber I got.

I don't understand what would be the problem with the chamber, can you explain ? I try to understand it, but this is weird for me...

 

[Florentoutang]

When I resize brass with this tool, I can feel when I reside the body, and at the end of the movement, I feel the shoulder going down (I think !)
Maybe chamber is too long for the cartridge ? In this case, is this solvable ?

 

[Jordanwickham]

Touch the ram then go a 1/4 turn more sounds like the instructions the die came with? Do you know your headspace and bump measurements or just going with die instructions? The failure to extract makes me think you are underheadspace bumping. I had this problem before on a 7mmrm that I neck sized for and forgot to body die down on a 3rd reload. Had a couple jam up really bad. But underheadspace wouldn't explain why your die is breaking like that. The die breaking would make me think you are over bumping by alot and the case has no where else to go but the weakest / most stressed because of lack of other support part of your die. I could be wrong on all accounts though.

 

[Jordanwickham]

When I resize brass with this tool, I can feel when I reside the body, and at the end of the movement, I feel the shoulder going down (I think !)
Maybe chamber is too long for the cartridge ? In this case, is this solvable ?

If you are headspacing proper you should hardly feel the bump going on.

 

[respiegel]

Which model Lee press are you using? That is an odd failure point for a die

 

[FLIGHT762]

You have a major malfunction going on. You need to do some measuring with a comparator or other gauge of your fired cases and the sizing of the cases. You need to get some help from someone who knows what their doing before continuing on.

Turning the die in, touching the shell holder then 1/4 is not cutting it.

Hope you get it figured out.

 

[sinister]

I had the same problem with .338 Lapua cases in a Redding T-7 press. The ram and dies were not aligned, so as the case was sized it put a lot of side stress on the die and I cracked three of them. I sent the press to Redding and they corrected the ram/die alignment.

 

[Florentoutang]

An info I forgot to give in my post.
I had to work on the shell holder to make it fit with the press.
Do you think this can be the problem ? Bad work on the SH...

If you are sure this is the problem I will have to buy another press, because the only SH for 338LM I got in New Caledonia dont fit well with my press...

 

[Jordanwickham]

Which model Lee press are you using? That is an odd failure point for a die

An info I forgot to give in my post.
I had to work on the shell holder to make it fit with the press.
Do you think this can be the problem ? Bad work on the SH...

If you are sure this is the problem I will have to buy another press, because the only SH for 338LM I got in New Caledonia dont fit well with my press...

338 Lapua Magnum or 338 Norma Magnum? A search I did showed that the shell holder issue on 300 NM seems to be a common issue posted about a few times. Seems that an RCBS #48 and Redding #35 seem to be the only SH that may fit that case. This was just from sifting through past Snipershide threads.

 

[Florentoutang]

I use hornady n°43, it's ok for my cartridgew, but it's not ok on my press.
Just bought another SH, is it worth to buy another press ?

 

[Jordanwickham]

I use hornady n°43, it's ok for my cartridgew, but it's not ok on my press.
Just bought another SH, is it worth to buy another press ?

Don't know what press you have. The guy who created the 300 NM as a wildcat, Jimmie Sloan, suggests using a Redding #35 or Lee #8 but in that post the guy who had the problem said the Lee #8 was, on some of the cases, pushing on the bevel that lead into the case head above the rim instead of the base of the case.

I would say with big Magnums you would want a beefy press. Not sure what you have for a press other than it's a Lee.

 

[Jordanwickham]

His issue was also with Norma Brass

 

[Florentoutang]

My press is the breech lock challenger.

Seeing differents sellers and shooters today, and they all says it comes from a bad chamber.

I try to understand what can be the problem with my chamber..
Wrong alignment with the barrel, or chamber too long/short ?

 

[918v]

Chamber too big, die too small, too much stress on the die walls, crack..

-reloading poems by 918v

 

[Evlshnngns]

My press is the breech lock challenger.

Seeing differents sellers and shooters today, and they all says it comes from a bad chamber.

I try to understand what can be the problem with my chamber..
Wrong alignment with the barrel, or chamber too long/short ?

Measure everything on a new and ounce fired piece of brass. Draw a diagram and compare. Saami should have specifications on what it should be.

Edit: this is an important part of reloading, if this is foriegn to you, get a mentor for some lessons.

 

[Florentoutang]

pushing on the bevel that lead into the case head above the rim instead of the base of the case.

I don't understand, I'm sorry, my english is not very well...

Chamber too big, die too small, too much stress on the die walls, crack..

-reloading poems by 918v

I dont think the chamber could be too large, when I shoot, I can't put back my brass in the chamber...

 

[FCS]

I don't understand, I'm sorry, my english is not very well...

I dont think the chamber could be too large, when I shoot, I can't put back my brass in the chamber...

Fired brass from your chamber won't go back into chamber? That can indicate chamber isn't concentric to bore or chamber is oblong. Measure a case with micrometer 0.200" above case head of a virgin case and a fired case. Measure fired case as a couple different spots axially to see if chamber is oblong.
When barrel was chambered, was a flush system used? Chamber polished by hand post cutting? If polished by hand, I've seen a bit of a flare to breech end of chamber that allows case to be larger than it should be, this requires extra effort/force to be sized down. 300NM in a 7/8-14 die is thin where breaking.

How much are you bumping shoulder when sizing?

Where are you located?
I might have an "extra" 300NM sizer die, Forster, that I'd sell.

 

[Jordanwickham]

Fired brass from your chamber won't go back into chamber? That can indicate chamber isn't concentric to bore or chamber is oblong. Measure a case with micrometer 0.200" above case head of a virgin case and a fired case. Measure fired case as a couple different spots axially to see if chamber is oblong.
When barrel was chambered, was a flush system used? Chamber polished by hand post cutting? If polished by hand, I've seen a bit of a flare to breech end of chamber that allows case to be larger than it should be, this requires extra effort/force to be sized down. 300NM in a 7/8-14 die is thin where breaking.

How much are you bumping shoulder when sizing?

Where are you located?
I might have an "extra" 300NM sizer die, Forster, that I'd sell.

He lives on an island off the East Coast of Australia above New Zealand. If your rounds go into the chamber without having any issues but they won't come out without issue, then fired cases won't go back in you definitely have a chamber issue.
If they go in easy it's a chamber issue.
If you have to get pretty physical with the bolt to get them in it is probably a sizing issue.

 

[918v]

I don't understand, I'm sorry, my english is not very well...

I dont think the chamber could be too large, when I shoot, I can't put back my brass in the chamber...

Your chamber IS too large because the sizing die has to work too hard to reduce the dimensions of the case and it cracks under stress. If your chamber was smaller then the case would be smaller and your die would not have to work so hard to size it.

 

[Tokay444]

Have you mic’d a virgin case and once fired case to compare them yet?

 

[Dolomite_Supafly]

Make sure the shell holder is not touching the sizing die. Use a couple of pieces of paper to set the clearance to see if it helps.

 

[buffybuster]

My 0.02 is a compilation of all these issues occurring:

-I think the chamber is not concentric.
-The press is at it's limit and not rigid enough to maintain alignment.
-The press does not support the die and the die is thin walled to begin with.
-Might be other shellholder issues.

Any single one might be OK, but altogether is too much.

 

[918v]

What is the diameter of the case before sizing at the bottom where the die is making contact? What is that diameter after sizing? What is that diameter on a new case?

 

[Tokay444]

What is the diameter of the case before sizing at the bottom where the die is making contact? What is that diameter after sizing? What is that diameter on a new case?

You’re only like the 10th person to ask...

 

[918v]

10th time’s a charm.

 

[dragman]

I have had it happen on 300WSM and RUM both. In the fatter cases there just isn't that much meat left around the base of the die. If the chamber is on the longer side and your trying to bump it it can happen as I did to me a few times.
from now on I make sure my chambers are a touch on the shorter side nothing crazy and if I can't get the shoulder bump easy I cut the bottom of the die off. to get a full size and desired bump. I have not had this problem since I started doing it this way.

 

[Florentoutang]

I'll measure my cases this weekend I think, when I will have some free time...
I come back with my results !
By the way thanks for your help

 

[sirhrmechanic]

I have never seen that type of die failure before. I’m interested in what the cause is as well.

Me either! To have one break, Inwould chalk up to a bad die. Two, from different makers?

Interesting thread!

Sirhr

 

[sirhrmechanic]

Have you access to another rifle in that caliber? In other words, can you fire rounds from a different rifle and try and reload them with your setup?

If the rounds from another rifle reload fine, then you have a chamber issue.

If you still have a problem reloading, you can start looking at a press or setup issue.

Can anyone from here send the OP a few cases fired from their rifle(s) to use as a control group?

Just a way to narrow things down.

Sirhr

 

[Powder_Burns]

Idk about the logistics or ramifications of mailing fired cases halfway across the globe, waiting to hear about OP’s brass dimensions between fired and sized cases.

 

[sirhrmechanic]

Idk about the logistics or ramifications of mailing fired cases halfway across the globe, waiting to hear about OP’s brass dimensions between fired and sized cases.

USPS flat rate box marked metrology samples, should get there in a week. Would be a simple test in cast the OP doesn’t have micrometers, verniers, etc.

Does the OP have access to the materials needed to do a chamber cast? Cerrobend is widely available to machine shops. Or Brownells sells its version. But it is all the same stuff.



IMHO, a chamber cast would give better info than fired brass if practical.

Sirhr

 

[Snuby642]

For safety I would recomend a second opinion from a gunsmith not involved with original barrel installation.

You don't have to tell your friends.

 

[Florentoutang]

Hi, some news after quite a long time..
I did not mesure cases, but all the setup has change : press, new die just recieved, and new shell holder...

Die broke in the exact same way than the 2 others after less than 100 rounds resized.

Tomorrow i'll bring the gun to the gunsmith to check the chamber.

If the chamber is wrong, is it possible to cut it on an MTU barrel to make a new chamber ?
And if possible, how long will be the cut ?

Thanks !

 

[918v]

Did you measure any of the cases prior to sizing them?

 

[Powder_Burns]

Nah he’s just gonna keep splitting dies expecting a different outcome.

 

[Tokay444]

Which gunsmith are you taking it to? The same one who chambered it?

 

[Herb Stoner]

What about sending a few fired cases and the broken die back to Forster? I've had good experiences with thier customer service.

 

[XLR308]

The press he initially said he was using I personally believe is questionable for the cartridge he is resizing.
I started out using a Lee challenger press in the early 90's and while they are a decent medium duty press I don't think they are up to the task of continuously resizing cases the size of 300NM.

The problem I noticed and the reason I ultimately retired and replaced the press is it for one has a cast aluminum frame and not a lot of bearing support surface for the ram.
When I started shooting and resizing 300WM more and more I started noticing play developing in the ram as the aluminum frames bearing surface deteriorated.
It sounds like he has other issues as well but deflection in the ram during sizing sure as hell can't be doing the die any favors.

 

[Powder_Burns]

The press he initially said he was using I personally believe is questionable for the cartridge he is resizing.
I started out using a Lee challenger press in the early 90's and while they are a decent medium duty press I don't think they are up to the task of continuously resizing cases the size of 300NM.

The problem I noticed and the reason I ultimately retired and replaced the press is it for one has a cast aluminum frame and not a lot of bearing support surface for the ram.
When I started shooting and resizing 300WM more and more I started noticing play developing in the ram as the aluminum frames bearing surface deteriorated.
It sounds like he has other issues as well but deflection in the ram during sizing sure as hell can't be doing the die any favors.

That was my initial thought as well. But he’s gone through 3 sizers in two different presses.

 

[XLR308]

That was my initial thought as well. But he’s gone through 3 sizers in two different presses.

I agree seems like he has more going on than just an undersized medium duty press being used for a large magnum case.
But hard to say since he is giving very spotty details at best and still hasn't provided any dimensional measurements of fired versus new brass dimensions.

 

[918v]

Hi, some news after quite a long time..
I did not mesure cases, but all the setup has change : press, new die just recieved, and new shell holder...

Die broke in the exact same way than the 2 others after less than 100 rounds resized.

Tomorrow i'll bring the gun to the gunsmith to check the chamber.

If the chamber is wrong, is it possible to cut it on an MTU barrel to make a new chamber ?
And if possible, how long will be the cut ?

Thanks !

Do you own a dial caliper or a digital caliper?

 

[Threadcutter308]

Maybe I don't get out much, but I've honestly never experienced or even heard of breaking a die, much less 3 of them.

I think there may be a gross mis-understanding of the process here. Hell, I used to neck resize and seat .338LM on a Lee hand press. Granted, it wouldn't bump or FLR, but I never had the expectation that it would, nor did I ever even try.

 

[Florentoutang]

Hi, here's some mesurements I made this morning before bringing the gun to the gunsmith.

The red arrow represents where the problem is to chamber a fired case.

The only prep. I made on the resized case is redding body die, no cut and collet resized, that explains some differences.