Dents on Case After Firing

[Mud]

Have you guys ever seen this? Any idea what caused it? I was on the sixth reload with this case. The load I was using:

300 Weatherby
COL 3.710
190 VLD Berger hunting bullet
74.5 grains of IMR 7828
CCI large rifle mag. primer

One of the guys at the range said my load is under powered. Another said it may be an oil dent. But after searching on the web. My guess would be since I have never annealed any of my cases. That when the cartridge is fired it can't create a strong seal in the camber and gas is leaking behind the shoulder causing dents. But I have also read that under powder loads and excessive free bore may also cause these kinds of dents.

Now I'm lost I don't know if I should abounded my current load and try to find a faster burning powder. Or if I should try stepping up the current charge.

This sucks because reloading components a very hard to find at the moment.

Larry

 

[Oldtrader3]

You are 6 grains below max if you are shooting 180 gr bullets. Your shoulders are denting because the pressure is too low to fully obdurate the case and seal it in the chamber. Plus shooting slow burning powders at low pressure is a possible way of blowing up your rifle! Maybe shoot a .308 if you want to save powder! Just my opinion.

 

[DrMike]

Rather difficult for me to accept that there is a failure to obdurate as there is no evidence of sooting on the neck. Charlie is correct, however, that you are shooting a low pressure load; you're slightly more than 10% below max charge with a 180 grain PT. I concur with him that if you want to shoot a low powered load, you should pick up a .308.

Time to put my oar in the water, I guess. I suspect moisture and/or oil in the chamber. The uniformity of the denting and consistency of placement would substantiate this conclusion.

 

[Mud]

Edited.

I'm using 190 grain Berger VLD hunting bullets. My charge is in the middle of what the Berger loading book recommends. Also, my muzzle velocity is averaging about 2760 fps when using 74.5 grains of IMR 7828.

 

[DrMike]

Edited.

I'm using 190 grain Berger VLD hunting bullets. My charge is in the middle of what the Berger loading book recommends. Also, my muzzle velocity is averaging about 2760 fps when using 74.5 grains of IMR 7828.

All the more reason to suspect a wet chamber.

 

[steve4102]

I can't comment on Berger's data as I do not have their manual, but according to Hodgdon you are 1gr below Min for 180gr and 1gr above Min for 200gr, that's pretty weak.

This is what QL calculated.

 Cartridge          : .300 Weath. Mag.
Bullet             : .308, 190, Berger M T VLD
Cartridge O.A.L. L6: 3.710 inch or 94.23 mm
Barrel Length      : 24.0 inch or 609.6 mm
Powder             : IMR 7828

Predicted data by increasing and decreasing the given charge,
incremented in steps of 2.0% of nominal charge.
CAUTION: Figures exceed maximum and minimum recommended loads !

Step    Fill. Charge   Vel.  Energy   Pmax   Pmuz  Prop.Burnt B_Time
 %       %    Grains   fps   ft.lbs    psi    psi      %        ms

-20.0   74    59.60   2208    2057   25197   9941     85.2    1.742
-18.0   75    61.09   2264    2162   26754  10314     86.6    1.701
-16.0   77    62.58   2320    2270   28407  10682     88.1    1.660
-14.0   79    64.07   2376    2382   30160  11043     89.4    1.621
-12.0   81    65.56   2433    2497   32022  11395     90.7    1.582
-10.0   83    67.05   2490    2615   33997  11738     92.0    1.544
-08.0   85    68.54   2547    2737   36099  12070     93.1    1.507
-06.0   86    70.03   2604    2861   38329  12388     94.2    1.467
-04.0   88    71.52   2662    2989   40701  12693     95.2    1.424
-02.0   90    73.01   2719    3119   43223  12983     96.1    1.384
[b]+00.0   92    74.50   2776    3252   45906  13255     96.9    1.345[/b]
+02.0   94    75.99   2834    3388   48758  13510     97.6    1.307
+04.0   96    77.48   2891    3526   51803  13746     98.3    1.270
+06.0   97    78.97   2948    3666   55045  13961     98.8    1.235  ! Near Maximum !
+08.0   99    80.46   3005    3809   58504  14154     99.2    1.201  ! Near Maximum !
+10.0  101    81.95   3061    3954   62195  14325     99.6    1.167  ! Near Maximum !

Results caused by ± 10% powder lot-to-lot burning rate variation using nominal charge
Data for burning rate increased by 10% relative to nominal value:
+Ba     92    74.50   2931    3624   55631  13215     99.9    1.237  ! Near Maximum !
Data for burning rate decreased by 10% relative to nominal value:
-Ba     92    74.50   2576    2799   37321  12503     89.1    1.481

A weak load is a distinct possibility here.

 

[1Shot]

I am with the "your load is too light" group. I have seen your problem a number of times when people try to load down a magnum. Weather magnums like most magnums need to run right up almost to the max on pressure to really shoot well. At least that is my experience. The Sierra manual list with their 190 gr MatchKing 73.2 grs start and 80.3 grs as max with IMR 7828 . You should be running that 190 VLD between 3000 and 3100 fps not in the 2700s.

 

[super-7]

I have seen quite a few un verified loads with 200 gr bullets with 7828 all the way upto 85 grs. If that's the case your a full 10 grs less. I do not take these loads as gospel but after running the factory Weatherby 200 gr partitions over the chrony I was averaging 3000 fps, I would say you have quite a bit of room to experiment. I would start bumping up your charge 2 grs at a time and load up 3 at each up to 82 grs or so, then shoot them over a chrony until your in the neighborhood of 2930- 3000 .

 

[SJB358]

I am with Mike here, it does look like something was in the chamber for those rounds. Seems hard to imagine there being gas leakage without some sooting on the neck and forward portion of the case.

I would take a chamber mop and clean it up, if possible. Maybe use some alcohol to make sure it is completely dry. Those dents are really deep and large. It would have me pulling my hair out some.

 

[AzDak42]

With those kinds of failures, I'd have a smith check it out before I proceeded. A few bucks to make sure there isn't some issue with the chamber is insurance on keeping one's eyes and face intact.

That said, if it does get the blessing from the smith, I'd find some factory ammo and see if you get the same results. If it doesn't, then I'd exactly duplicate a starting load in one of the manuals and start from there.

Scary stuff mate - be careful.

 

[BeeTee]

I shot and loaded for a 300Wby for many years. I experimented with reduced velocity hunting loads in the 1970s (when I was stationed in central CA), for coastal blacktails and similarly sized critters. In my case, I used 60gr of IMR4895 or H4895 behind a Speer 150gr flatbase spitzer, and shot that load hundreds of times. Even killed an elk with that load.... Never had a problem with case dents, and that load would print sub MOA. Didn't have a chrono, but I figured it was about 308 Win speeds. 4895 is a very versatile powder.

I agree with others here that blame low pressure loads using slow burning powder. Try 4895.... BT

 

[yellow dog]

I had the exact thing happen in my 300 Wb if I remember right Walt Berger sent me load info from quick load. QL is supposedly a little "stumped" by the weatherby free bore.

I ended up ragging the chamber with "witches brew" and then "hoppes" then several swipes with alcohol. stepped my load u p by .5 grains for several grains and it went away. you could actually see the dimple get smaller, and not every one would do it (it would only happen on multi fired un-annealed brass). I don't like posting un published load recipes but that is what I did.

It never hurts to have a gun smith look at the chamber so you or your gun don't get hurt.

 

[super-7]

I am with Mike here, it does look like something was in the chamber for those rounds. Seems hard to imagine there being gas leakage without some sooting on the neck and forward portion of the case.

I would take a chamber mop and clean it up, if possible. Maybe use some alcohol to make sure it is completely dry. Those dents are really deep and large. It would have me pulling my hair out some.

As I understand it , and this is from a Seirra reloading manual, it's not really a gas sealing issue but more of a Venturi effect. With the lower charge of slow burning powder as it expels you are actually sucking in the side of the case. Again it's rare but does happen from time to time.

 

[SJB358]

I am with Mike here, it does look like something was in the chamber for those rounds. Seems hard to imagine there being gas leakage without some sooting on the neck and forward portion of the case.

I would take a chamber mop and clean it up, if possible. Maybe use some alcohol to make sure it is completely dry. Those dents are really deep and large. It would have me pulling my hair out some.

As I understand it , and this is from a Seirra reloading manual, it's not really a gas sealing issue but more of a Venturi effect. With the lower charge of slow burning powder as it expels you are actually sucking in the side of the case. Again it's rare but does happen from time to time.

Got ya. Makes sense to me.

 

[Guy Miner]

Mud - have you tried a factory loaded cartridge for comparison?

Weatherby loads their ammo on the warm side, but it usually shoots rather well. Might make for an interesting comparison.

Your load:
300 Weatherby
COL 3.710
190 VLD Berger hunting bullet
74.5 grains of IMR 7828
CCI large rifle mag. primer


Berger recommends from 72.5 - 78.2 gr IMR7828ssc, but I see that even their minimum load is producing 2826 fps, which is more than you're seeing with your middle-of-the-range powder charge. I'd say your rifle is begging for more 7828. Your big Weatherby case is seriously under-employed right now. At 2760 fps, you're seeing velocity similar to what a well-loaded .30-06 can produce.

With my .300 WSM I'm getting more velocity, from a heavier bullet, from a smaller case, and I'm not over-loading it. The big magnums thrive on largish charges of slow burning powder pushing heavy bullets.

BTW - that 190 VLD is one heck of a bullet and should serve you well, but consider trying the 210 VLD if you can find some. It's even better.

Don't hesitate to use that big Weatherby case as intended - shoving heavy bullets hard. It excels at that task!

Regards, Guy

 

[JD338]

I agree with the others, you need to increase the powder charge weight and increase the chamber pressure.

JD338

 

[woods]

Dents like those appear when gas is passing the case body / shoulder junction. Very typical with a case head separation where the gas escapes out the separation close to the case head and is squeezed out toward the neck with case expansion and exits out the barrel.

Since your cases do not have any cracks around the pressure ring it is probable that gas is getting on the outside of the neck between the neck brass and the chamber and the brass is the path of least resistance compared to trying to follow the bullet down the barrel.

Bump your powder charge

 

[ScreaminEagle]

I don't know what caused that, but i do know for a fact that the military guys here have seen that before.

I've seen it tons of times, while firing 5.56 at the range!

 

[Mud]

Thanks for the feedback everyone. I really appreciate it.

I know my chamber was clean before shooting. I wipe it dry every time before I go shooting by running a couple of dry patches in the chamber and barrel.

After spending some time researching the Internet and looking at other forums, I suspect I was under charging my hand loads. There are several variables here.

Longer COL at 3.710 vs. 3.560 Berger recommended COL
Larger than normal case or low a load density
The huge amount of free bore Weatherby's have
Slow burning powder

This explains why I was chonying 2760 fps vs. 3000 fps that the Berger manual lists. I think I just may need to step up my hand loads. I have always worried about over powering my loads that I never gave under power load issues any thought. I guess this experience is a tough one learned.

I am going to ditch the 190 Berger VLDs and start using the 210 Nolser Long Range Accubonds that I just bought. I believe the heavier and longer bullet will server my 300 Weatherby better.

Thanks again for the input.

Best,

Larry

 

[Oldtrader3]

Absolutely, good luck with that, Larry!