Too much pressure? 300 RUM

C

camokid

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Reloaded some 300 RUM with
180 grain Accubond and 95 grains of Retumbo. Everything from
specs in Nosler Reloading Guide #7
Am I seeing signs of pressure on the Primer?? "Crater"
Or is that just my firing pin?
So I then reloaded 94.5 grains of Retumbo. Same results...
Should I be worried or am I just paranoid?

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LAST EDITED ON Nov-12-17 AT 07:50PM (MST)[p]I looked for bolt face imprint, these were a touch hot. Your primer will flatten, I couldn't really tell using the lip around the primer strike.

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Another thing about reading primers is you need to remember not all primers are created equal. Some primers have harder cups than others and will show signs of cratering and flattening at lower pressures.

What you don't want to be doing is trying to find a max load in this cooler weather and think you are good to go. You may get a big surprise shooting that max load that you worked up in 50 degree weather when you shoot it in July.
 
LAST EDITED ON Nov-13-17 AT 09:19AM (MST)[p]The cratering is bad, but the primers aren't that flat. a sloppy pin fit could be the cause.

It does look like you have some shinny spots on the head ? that's a sign of excess pressure.

I assume those are Remington primers by the color. in my experience they're the worst primer on the market I dumped them years ago. if you can find Federal 215's that's what I'd use from now on.












Stay Thirsty My Friends
 
Definitely a sloppy firing pin hole. If your worried about it send it to Gre Tan. Greg will fix it and have it back to you in a week or so.

As far as your reload is that new brass? FL sized? Neck sized?
How was bolt lift after firing? Do fired cases chamber easy?
I would also recommend a different primer. Try some CCI 250 or Fed 215 if you can find them.
 
LAST EDITED ON Nov-13-17 AT 12:50PM (MST)[p]LAST EDITED ON Nov-13-17 AT 12:47?PM (MST)

The brass has been shot and reloaded maybe 3-4 times. And full length sized every time. Bolt lift is easy and normal after firing. And are Winchester WLRM primers
 
It doesn't sound or look like pressure. The firing pin would benefit from bushing it and also keep it centered.

This is just an assumption but you might be sizing your case to much and creating excessive headspace and stretching the brass.
What is your process for FL sizing and how is your FL die setup?
 
I full length size them with RCBS full length size. With a slight over cam on the press. They're probably on their 3-4th sizing.
 
Primers are a piss poor way to judge pressure. You are at start loads for that bullet and powder. Have you chronographed your loads? You are at Nosler's minimum. With no sticky bolt lift, and no excessive velocity when shot over a chrono, I wouldn't worry about it. I wouyld, as suggested, try to find some 215's. I've been loading the RUM's since 2000. All I've ever used. mtmuley
 
A slight cam over is usually way to much sizing and pushes the shoulder back way to far
Screw your die down til it touches the shell holder. Back it off about a 1/2 turn and begin sizing your brass. Keep screwing the die down til you are just bumping the shoulder .001-.002. You can measure it with a datum line gauge or soot the shoulder and keep sneaking the die down til it just touches it and chambers.
I also recommend imperial sizing wax for lube of the case.
 
The OP's sizing isn't an issue. No obvious pressure signs other than the percieved primer concern. I sized brass for my personal.300 RUM that way in 2000 until I got the tools to measure accurately. mtmuley
 
Touph to tell the pressure by just a primer pic.
But, the firing pin could be causing your primers to appear the way they do. Not necessarily a bad thing but pin slop can deter accuracy if excessive. Probably nothing to worry about though from what I see.
Pressure probably will cause a hard lifting bolt after you fire. Primers can be hard to read. Bolt face brightened with brass is another good sighn to back it off some. Primer pockets being over expanded to the point that primers go in to easily is another sighn to look for that says things are getting warm.
Hot loads can cause any, some, and all these things. But don't worry to much unless bolt handle lift is substantial.
You really have to go pretty far to exceed the safe parameters.
When we work up loads with reputable data it is likely OK.
You know you definitely went to far when gas sperts out of the pressure release port on the chamber.
It's good to not get that far gone. But carefully followed data will keep us very well below that danger zone.
I would say your far off from serious pressure.
 
I'll try backing off the sizing die. And definitely do the chrono soon. Thanks guys for the advice. I was stressing about it.
 
I've been waiting for mtmuley to chime in. Thanks for the wealth of knowledge ya'all are inputting. I'll learn all I can for sure. Thank ya kindly
 
You never said if you're trimming to the correct length. if you're not that's probably your problem.










Stay Thirsty My Friends
 
Mt- I agree sizing isn't his problem. I was just trying to help him eliminate another problem that many people never even think about and it really helps save brass from thinning and splitting quickly.
His brass looks fine to me and easy bolt lift sounds good. A chrony would definitely tell the tale but like you said it's loaded pretty mild.
 
I need to look and see if I have any factory Remington once fired brass that I haven't loaded yet. I doubt I do, but I seem to remember the primers looking like camokid's photo. mtmuley
 
If the bolt isn't sticky, the primer isn't flat and there are no shiney spots on the head then I don't see a problem with the load.

Your crumby firing pin fit seems to be the only issue . I would get it fixed or dump the gun. especially if you want to push max loads.


















Stay Thirsty My Friends
 
Yeah it just the primer that bothers me so far, of the crater and very very slight flattening. I'm touching holes at 100 yards so my load is where I'm wanting to stay and not push max loads. Why dump the gun if not fixing the firing pin?
 
>Yeah it just the primer that
>bothers me so far, of
>the crater and very very
>slight flattening. I'm touching holes
>at 100 yards so my
>load is where I'm wanting
>to stay and not push
>max loads. Why dump the
>gun if not fixing the
>firing pin?

because you are bleeding pressure into the bolt.....bush the firing pin or dump it


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So i did some backtracking and remeasured my C.O.A.L.... BIG mistake on my part,
and it was around 3.600 with cheap digital calipers, with the 180 grain Accubond. I since have upgraded to the Lyman Dial stainless steel calipers and the Lyman measured 3.645 - 3.650. Which is .45-.50 thousands over S.A.A.M.I in the Nolser #6 guide.
 
You can't get anywhere near close enough to the lands to worry about it with a factory chamber. At least that's been my experience with a half dozen RUMs. mtmuley
 

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