.300 Win Mag

[RKRNC]

Hi Folks.

Lot's to read out there on the .300 Win Mag. My question relates to brass:

I have read that reloading is limited to about three times because belted cases tend to "case-head separate". Does anyone have any experience with this? Are there recommendations that would allow a person to avoid this / extend the number of reloads?

Thanks for taking the time to educate me.

RK

 

[freakshow10mm]

Neck size. I load my 375 H&H Mag brass (the original belted magnum) about 8 times before it wears out.

 

[MCMXI]

Neck size.

+1

Belted magnums head space on the belt, so if the shoulder is unsupported in the chamber, this will put more stress on the rest of the case, particularly at the belt. The shoulder can be touching the chamber wall, 0.001" off, 0.003" off, 0.005" off etc. Intuitively, the further the case shoulder is away from the chamber wall, the more room it has to expand forward and outward. The more it deforms the greater the stress on the case. After a few firings, provided you neck size only, the head space dimension of the case will stop increasing as the case is formed to the chamber. At this point, the case has as much support as it's going to get. The other issue is that each time you full-length size a case, the case typically increases in length. This is accompanied by a thinning of the case wall which can reduce case life as well. I'm on my fifth loading of W-W Super .300 Win Mag cases and they stopped "growing" after the second firing. I haven't had to trim the cases at all and I haven't lost any of the 100 due to case head separation. In addition, I don't have any problem closing/opening the bolt with minimal effort.

 

[Kernel]

Somebody's been reading their new Amercian Rifleman.

 

[Grumulkin]

How soon the brass wears out depends on how hot the loads are, how it's resized, case design, chamber dimensions and brand of brass. Even with neck sizing, I don't think 300 Win. Mag. will go much beyond 4 or 5 reloadings.

1. Hot loads; fairly obvious; the brass will stretch more.
2. How it's resized; neck sizing works the brass less.
3. Case design; tapered cases stretch more than straight walled casses.
4. Chamber dimensions; in a tight chamber, cases will stretch less.
5. Brass brand makes a big difference. In one study, Remington brass came out on top when number of reloadings and price of brass acquisition were considered.

If you read the American Rifleman article, you know about the wire; that really works. Run a wire with the tip bent to 90 degrees down the inside of the case to see if there is a groove near the head; if there is, toss the case. Another thing to look for is a bright ring (it may be subtle) in the brass just beyond the case head which means head separation will probably happen in the next 1 or 2 firings of that brass.



The bright ring on the case with incipient case head separation is easily seen. Also pictured is the wire (a large paperclip) used for diagnosis. The cartridge is a 300 Win. Mag.

 

[243winxb]

With a true maximum loading, 3 loading is tops in any case, even with controlling shoulder bump or neck sizing IMO. Unless you have very good custom fitted dies matched to the chamber.

 

[MCMXI]

With a true maximum loading, 3 loading is tops in any case, even with controlling shoulder bump or neck sizing IMO. Unless you have very good custom fitted dies matched to the chamber.

If you're neck sizing only, why would you need "custom fitted dies matched to the chamber"? Good picture although I don't agree with your statement that "3 loadings is tops".

RKRNC, the match load for my .300 Win Mag is a 208gr A-MAX, W-W Super case, 71.7gr of Reloder 22 and a CCI 250 primer. The muzzle velocity is 2,885 fps ... so definitely near the upper end of the scale. As I mentioned, the W-W Super cases have been fired four times already with no sign of case head separation. I do have a Krieger barrel and I use Redding competition dies.

On a side note, I have 100 W-W Super cases and 100 Norma cases. The average weight of the Norma cases (Avg. = 215.4gr, SD = 0.53gr, ES = 2.4gr) is 10% less than the average weight of the Winchester cases (Avg. = 239.1gr, SD = 0.64gr, ES = 4.2gr). I've only fired a few (10) of the Norma cases once so I can't say anything about their longevity.

 

[RKRNC]

Thanks everyone. Great stuff. I have gotten a great deal of good information/advice on this forum. It's not that I doubted the article (great job seeing that one, Kernel), I just believe that multiple sources give a greater scope of understanding. Not to mention that the timing was just scary; the rifle arrived Friday, the magazine on Monday.

I am going to be reloading for the brand-spankin-new Remington 700 5r Milspec that my wife now calls "the other woman".

1858, I'm using the CCI 250's also, but with H4831 behind 150 gr Nosler ballistic tips (and Berger 190gr VLD's when they get here).

RK

 

[jbkebert]

Warning diclaimer contains load data. Always start low and work your way up the scale with any load.

The only problem with neck sizing only that I have run into. When I load for my encore which has a oversized chamber due to the nature or the break action. The shoulder is puched forward and has to be full length resized to work again. I have tried neck sizing only but have problems with the gun not wanting to lock up afterwards. In a bolt action rifle neck sizing may be okay. my experience with the T/C isn't the same. unless someone can tell me I have doing it wrong? Even full length resizing with quality brass i have gotten 5-6 loadings. I use 180 grain interbond with 72.8 grains of reloader 22 and a WLRM primer and hornady brass.

 

[243winxb]

If you're neck sizing only, why would you need "custom fitted dies matched to the chamber"? Good picture although I don't agree with your statement that "3 loadings is tops".

2 things. First, even if you neck size only, there is an area of the brass that is always unsupported. This area is where the bolt meets the barrel. The gap is about .010" Some bolts/barrels gaps are set as small as .002" on a custom barrel install. The web is thick in this area, but high maximum pressures can and will expand it. Remember, every time the brass is fired, it expands, then springs back. Now as for custom dies, they can not fix the problem with the .010"gap. But if using midrange loadings, a custom made die will most alway extend brass life. The belt is used for headspacing and has slop of about .005" , so headspacing on the shoulder helps with case stretching in the body. A custom die will not overwork the brass in front of the belt when FLRS. Neck sizing is as good as custom dies for extending case life, but soon or later you must FLRS or bump the shoulder back as some call it.

 

[Grumulkin]

The only problem with neck sizing only that I have run into. When I load for my encore which has a oversized chamber due to the nature or the break action. The shoulder is puched forward and has to be full length resized to work again. I have tried neck sizing only but have problems with the gun not wanting to lock up afterwards. In a bolt action rifle neck sizing may be okay. my experience with the T/C isn't the same. unless someone can tell me I have doing it wrong?

Actually, my 300 Win. Mag. is also an Encore. They don't really have an oversized chamber any more than a bolt gun does. The difference is that there is so much mechanical advantage with a bolt gun that they will fairly easily chamber a cartridge that is a little bit too long. In the Encore, you may need to close the action briskly but it will still generally close even if you only neck size.

Interestingly, in neck sizing for Encores and Contenders, the only cartridges I've had problems with a tight fit in has been belted magnums. I've never had problems with cartridges like 308 Winchester, 25/06, 30/06, 7mm/08, 270 Winchester, etc.

 

[jbkebert]

I had some .308 rounds I loaded for the encore. I could close the action but could not cock the hammer. Not sure what the heck was going on. I even tried some casing with just primers. Same problem. I fired off the primers in another gun and set my die a little deeper. Locked up without a problem?? the only thing I could figure out was that I needed to push the shoulder back a couple thousandths. After that i just full length size and have little or no problems.

 

[RKRNC]

243winxb, those are some awesome (and very helpful) photos! What did you use to cut the case on the left? The spirals really enhance the overall effect. They lead the eye to the details of what is going-on inside the case. I would have thought there were smoother transitions between high and low areas. The "waves" really convey the turmoil that is occuring inside that case. I'm also pleased to see the slight bevel before the belt. I was worried that my sizing wasn't really "full-length" - that perhaps I wasn't doing something right (always a possibility).

Grumulkin, thanks for providing an excellent image of that "bright ring". I'll be looking for that. Is the bottom case one that actually separated? If so, would you be so kind as to describe that experience? How did you remove the case from the chamber?
Thanks.

As a teacher, I have often thought that there are so many physics lessons (+chemistry)that can be conveyed through the practice of shooting. The fact that the kids (HS age) would be having fun would just reinforce the learning.

 

[243winxb]

RKRNC, not my photos. The brass had been fired something like 10 times with midrange loadings if i remember correctly. The photo was such a great example of case head seperation i had to save it here. http://www.photobucket.com/joe1944usa

 

[MCMXI]

243winxb, are those cases in your photo .338 Win Mag or .300 Win Mag?

The "waves" really convey the turmoil that is occuring inside that case.

Not really ... what you see is necking of the case wall and a clearly defined plastically deformed region due to the case elongating. This is akin to running a tensile test in an Instron to determine the yield strength and ultimate tensile strength of an alloy.

The belt is used for headspacing and has slop of about .005" , so headspacing on the shoulder helps with case stretching in the body.

And that's exactly what neck sizing only does ... it helps to support the case by reducing the amount the case elongates (and strains) as the round is fired and also as the case is sized, not to mention reducing the amount of cold working of the brass.

there is an area of the brass that is always unsupported. This area is where the bolt meets the barrel. The gap is about .010" Some bolts/barrels gaps are set as small as .002" on a custom barrel install. The web is thick in this area, but high maximum pressures can and will expand it.

Yes, the bolt nose is a few thousandths off the base of the counter bore, but the part of the case that is unsupported is the region below the red line in the photo below. The brass in this region will only flow if there's excessive case pressure, the kind that leaves an ejector mark or other marks on the case head. If a belted case is going to fail, it'll fail above the belt (as you show) for a reason. This is where the case wall is subjected to the most stress and strain.

 

[MCMXI]

RKRNC, I don't want to get into a big argument over this. I know what works for me, my loads and my rifle. You may get 3, 6 or even 12 loadings from your .300 Win Mag brass ... it's going to depend on a number of factors.

 

[243winxb]

are those cases in your photo .338 Win Mag or .300 Win Mag

.338, Not my photos. Here is the complete thread with photos. http://castboolits.gunloads.com/showthread.php?t=54771

You may get 3, 6 or even 12 loadings from your .300 Win Mag brass ... it's going to depend on a number of factors.

I agree.

 

[Grumulkin]

Yes, the one case has a fully separated head and I did it because I was stupid. I loaded the case, saw the ring and decided to shoot it anyway. Anyway, in a gun with a strong action, a head separation with a load that isn't over pressure isn't a disaster though it's something you should try to avoid. The case was easy to remove; I put snap ring pliers that open when the handles are pressed inside the broken off case and it easily came out.

As for the problem cocking an Encore with a chambered case; the reason is that the action is not closing fully even though it looks like it's closed. If that's happening bumping the shoulder back will cure the problem; if you close the action a little harder that will probably allow the cocking of the hammer as well.

 

[RKRNC]

RKRNC, I don't want to get into a big argument over this

1858, I'm not an experienced enough reloader to argue with anyone. I really appreciate the experience and knowledge that you and other members of this forum are willing to give away.

This particular topic has proved to be most helpful. I need more cases.

RK