I have a problem with a new rifle that is driving me batty and was hoping I could get some thoughts.

Rifle is new Ruger American Magnum in 338 WM. Cases are Hornady. I worked up a load with 210 gr TSX and stopped at 66 gr of H414, off max.

I am getting classical case head cracks in two firings.

I measured the new resized brass, the brass after firing, and the brass after firing and resizing. I was using a Lee full length die. For comparison, I bought a box of Barnes factory ammo for comparison. My measurements were with a Hornady headspace collar kit and was consistent.

New brass (unfired) and the Barnes factory ammo measure the same. The die does not set back the shoulder as far as I can measure.

After firing, the headspace gage indicates it moves roughly 0.013". A slight ring is visible ahead of the case head under magnification.

I was thinking excessive headspace on the rifle. One thing that confuses me is that when set up per Lee's instructions, the full length die sets the headspace to within a few thousandths of the fired brass, but still 0.010" longer than the factory ammo or the new brass.

Do I have a rifle with excessive headspace? Defective die? Both? Is this a fact of life with belted magnums that headspace off the belt?

Is 0.013" too much stretch? I understand go/no go gages to chamber are 0.004-0.006"? I will try to find a local gunsmith with a set of 338 WM gages before I call the rifle bad.

Sounds like it could be excessive head space. I just neck size my .338 WM brass. No issues.

Headspace on belted mags is not measured to the shoulder, but you should treat your brass as if it was.
Stop resizing your brass so much and the case separation will stop.
As 4six said, he just neck sizes and therefore does not touch the shoulder. His brass fits well. Make yours do the same.
For reference, the difference between minimum mag brass and a max chamber is about .018.
So, forget about the belt and headspace; make your brass fit as closely as you can, base to shoulder. Adjust your die so as not to set the shoulder back so much.
In actual fact, your dies and chamber both probably fit within SAAMI specs. But that leaves a lot of room for "error", when reloading. Not for shooting factory ammo, once.
Oh, there is only one mag headspace gauge; one size fits all. Base to belt; as I said, where the shoulder is, is not used in gauging chambers, but you should treat it like a regular rimless case.
You could get a belted no go gauge from Brownells and check your rifle. Cheaper than shipping it to me. I bet it is fine.

I also think your load is a low pressure load; might try a higher pressure one first to fire form your brass the first time.

quote:

Originally posted by dpcd:
Headspace on belted mags is not measured to the shoulder, but you should treat your brass as if it was.
Stop resizing your brass so much and the case separation will stop.
As 4six said, he just neck sizes and therefore does not touch the shoulder. His brass fits well. Make yours do the same.
For reference, the difference between minimum mag brass and a max chamber is about .018.
So, forget about the belt and headspace; make your brass fit as closely as you can, base to shoulder. Adjust your die so as not to set the shoulder back so much.
In actual fact, your dies and chamber both probably fit within SAAMI specs. But that leaves a lot of room for "error", when reloading. Not for shooting factory ammo, once.
Oh, there is only one mag headspace gauge; one size fits all. Base to belt; as I said, where the shoulder is, is not used in gauging chambers, but you should treat it like a regular rimless case.
You could get a belted no go gauge from Brownells and check your rifle. Cheaper than shipping it to me. I bet it is fine.

If the initial firing is stretching the brass 0.013" and leaving a slight ring, isn't most of the damage done there? The second reload was only a few thousandths bump of the shoulder. If the damage is done in the first fire, then this brass is essentially one fire only in this rifle as the case head is thinned during that initial fire form. Correct? Am I missing something? Seems like the 0.013" I am getting or the 0.018" per the spec is essentially leaving the case compromised in the first fire. Thus, making them unable to reload safely.

Thanks for the help. I will try to get some pics tomorrow.

your moving the brass forward 100th of an inch too much.
and then pushing it back again too much.
then forward again to the breaking point of the place where the brass is coming from.

never mind what barnes or factory brass measures they are made to fit in any gun in that caliber.
you only need to concern yourself with your gun in that caliber.

unscrew the die so your only bumping the shoulder back about .002 or .000 for the first reload or two and measure your brass again, then set it for the .002 push.

I am inclined to believe that this rifle has a very generously cut chamber.

Only time I have seen this happen is due to this.

BTDT. You need a workaround. First, factory loads are going to stretch. So that's not going to be the way to go except/unless you're willing to forego reloading the cases.

Had a .300 Win with that "disease". I used to charge powder in new brass to starting load level, seat bullets out so they'd stick in the rifling, and fireform to chamber. That works mostly, but there's a better way.

Run your brand new .338 brass over a larger diam expander (.358, or .366, or even .375) in your case. Then set your .338 FL die to size the neck back down and back over the .338 button.....little at a time....till you have a false shoulder that allows you to close the bolt with a bit of resistance. You can full charge the load, or not.

This more reliably prevents that first big stretch IME. Subsequent reloads you can bump the shoulder 0.002" or thereabouts.

It's not a 100% perfect solution, but it works good enough.

quote:

Originally posted by Samuel_Hoggson:
BTDT. You need a workaround. First, factory loads are going to stretch. So that's not going to be the way to go except/unless you're willing to forego reloading the cases.

Had a .300 Win with that "disease". I used to charge powder in new brass to starting load level, seat bullets out so they'd stick in the rifling, and fireform to chamber. That works mostly, but there's a better way.

Run your brand new .338 brass over a larger diam expander (.358, or .366, or even .375) in your case. Then set your .338 FL die to size the neck back down and back over the .338 button.....little at a time....till you have a false shoulder that allows you to close the bolt with a bit of resistance. You can full charge the load, or not.

This more reliably prevents that first big stretch IME. Subsequent reloads you can bump the shoulder 0.002" or thereabouts.

It's not a 100% perfect solution, but it works good enough.

My brother had a 300 Bee and he had to do the same thing. After that as others have said, treat it like any non-belted cartidge and size only enough to allow reliable chambering.

Right, what Sam said; that is the next thing I was going to tell you; expand your necks to .35 caliber and form a false shoulder, then neck back down to 33. That will hold your base against the bolt face. Or use the "jam a bullet into the throat" wildcat case forming method. That works too. Don't use max loads if you do that. Treat it like a wild cat. Forget all the gauges; your chamber is the gauge.
But first, just for your peace of mind, get a magnum no go gauge and see what it is.
Or send it back to Ruger, but if they check the headspace and (when) it is good, you will just get it back, as is. Factory rifles are not sold for reloaders and you have voided the warranty by shooting them. Every Ruger owner's manual says not to shoot reloaded ammo. I'm sure no one here ever does......

I pulled the SAAMI specs for 338 WM. My interpretation of the max cartridge/min chamber would allow a 0.026" difference in the shoulder dimension at max tolerance.

That seems a bit dangerous as I am getting thinning and unable to reload at about 0.013" difference.

My measurements have the chamber and ammo in spec. I understand the responses and causes of the separation, but the gross thinning at the first shot still has me a bit befuddled. I imagine a lot of belted mag rifles out there with this same issue. And these calibers are commonly reloaded.

quote:

Originally posted by metalman29:
I pulled the SAAMI specs for 338 WM. My interpretation of the max cartridge/min chamber would allow a 0.026" difference in the shoulder dimension at max tolerance.

That seems a bit dangerous as I am getting thinning and unable to reload at about 0.013" difference.

My measurements have the chamber and ammo in spec. I understand the responses and causes of the separation, but the gross thinning at the first shot still has me a bit befuddled. I imagine a lot of belted mag rifles out there with this same issue. And these calibers are commonly reloaded.

I had the same issue with a 300 Win Mag. Solved all my problems knowing there was an issue and started my new brass with a fire-forming session before use. I bought some cheap blemished bullets from Midway, used Trailboss powder and got to fire-forming my brass. Brass is on several reloadings now versus the three I was getting before.

Right.
Shoulder dimensions are immaterial on belted magnums, as far as SAAMI is concerned. Only the belt is held to a tighter tolerance and those are none too tight.
As stated many times, you must treat your process as if with standard bottle necked cartridges.
And as I said, factory rifles are made for factory ammo fired once. Yes, many, (Me) reloaded all manner of belted ammo; you are just have more challenges to overcome.

Many years ago, a friend on AR recommended that we never use a GO gage for chambering belted magnums.

I went through a whole bunch of brand new belted cases, measuring the headspace on the belt.

I kept the one with the smallest measurements, and have been using that one as my GO gage for all belted magnums we build.

Never had anyone complain of any factory ammo not fitting in.

Nor do we get any complaints of this sort of thing happening either.

With rounds loaded all over the world fired in firearms made all over the world in some firearms made over 100 years ago, it's a wonder any of this stuff works. SAAMI is just a guideline to help everything fit no matter what. Like DCPD said, load for you own rifle and don't worry what the specs say.

Thanks for all the help and suggestions.

I fully understand the geometry and to fire form then treat as regular non belted and set the shoulder back a minimum amount. . However, this is essentially what I did and I still got a rupture on the second fire.

Process
- Form/Load new brass. The shoulder was not moved in this process.
- Fire. The case stretched 0.013".
- Resize. This set the shoulder back 0.003". I will fully admit this was by luck than my careful planning. But it happened in about the manner one would prescribe for case life.
- Fire second shot - This is where the separation happened.

The case has to grow that initial 0.013" no matter what. I can either use the larger expander ball trick to set a false shoulder. I don't see how I could fire form better than what actually happened unless low power loads work the case less. From the geometry or the resizing after fire forming between 0.001' and the actual 0.003" would have made a significant difference.

It appears the area ahead of the belt is where the initial deformation/thinning of the brass will concentrate.

It also appears much/all of the case life is loss in that initial fire in my chamber.

Did you check the head clearance (not headspace, per se) with tape as I suggested? I recommend you do not make that "first fire" at all, without fitting your brass to the chamber as if it was a wildcat.
Some have advocated oiling your brass first, which won't allow it to adhere to the chamber, thereby causing all the stretching to occur at the shoulder, where it will cause no harm, but I can't recommend it. Didn't say it won't work.

quote:

Originally posted by metalman29:
The case has to grow that initial 0.013" no matter what. I can either use the larger expander ball trick to set a false shoulder. I don't see how I could fire form better than what actually happened unless low power loads work the case less.

Don't think you're understanding the process. You want to relocate the shoulder on new brass so that it abuts the front of the chamber. You do this by expanding to larger diameter and then sizing the neck only as far back as necessary. You want the new shoulder to be snug against the chamber walls right at the junction of neck and shoulder. When you fire that 1st round, the sidewall material still needs to stretch, yes. It will. But you want the metal to stretch evenly from the length of the case, not only from just past the belt as is happening now.

That's the idea, and it works well in practice.

Right; if you do as I said, your brass will grow, sure, but all the growth will be at the SHOULDER, where it won't cause any problems at all, and not the HEAD, where it is causing your issue. (Because the head will be held against the bolt face, making it impossible to stretch there.) You want all the brass elongation to occur up front.
From that point on, do not size your brass too much; disregard the factory instructions for die setting.

quote:

You want all the brass elongation to occur up front.

Yep. And that will be achieved by following the advice in the posts above. Once stretching forward of the belt is restricted the only thing you should periodically check is lengthening of the neck. Relative to the load you shoot and the resizing process brass growth still occurs and this is most likely in neck lengthening. At some point neck trimming is necessary.
At least my 2 cents worth based on my own .300 WM handloading.

A false shoulder on new brass adds life to brass....

Try it

Although redundant,it sounds like a headspace issue to me as well.I agree with dpcd in the neck sizing only.Thats what I do. also the opening the neck to 35 then back down to 33.Thats what I do to form my brass for the .30 Gibbs.Of course instead of 33 its 30.When fireformed you now have a perfect case to chamber mate.

your not just fighting forward stretch your fighting outward stretch too.
if you notice many rifles have this issue then they send that once fired brass onto the next guy that can't make it fit his rifle until he gets a sizing ring that goes all the way down to the belt.

you don't have that issue but could create the second for someone else if you gave them your brass.

by creating the false shoulder your keeping as much brass as possible back in the chamber so it can go outward and not out and forward.

As many have already said, you have to ensure all the stretching to 'set' the headspace is at the shoulder. Don't know what Hornady brass is like in terms of correct annealing, but annealing the shoulder and neck area of your new brass will ensure it is at it's softest to encourage stretching after a false shoulder has been applied as others have suggested.

quote:

Originally posted by Saeed:
I am inclined to believe that this rifle has a very generously cut chamber.

Only time I have seen this happen is due to this.

If it's generous on length I'd also advise to seat the bullets so that they jam into the lands when firing for the first time. After that neck size so that the rounds chamber with a slight bit of effort or no effort if you're intent on facing a dangerous critter.