Is pressure too high? .30-06, IMR 4350, 165 grain Accubonds

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OK, the consensus is that this load is way too hot. I accept that. Thanks!

(Darn! This load not only zings, but it's superbly accurate! :()

Being an engineer, I like numbers. Does anyone have a copy of QuickLoad to run the numbers for this load? Now I'm really curious to see what the calcs say.

Thanks!
 
Brian,

I sent you a PM with the water data plus lots of other data.

How much of an effect is there for seating the bullets, say 0.020" or 0.030" from the lands instead of the 0.010" I used for these loads.

Thanks!
 
I just checked two reloading manuals, Lyman and Nosler and both listed max loads of 57.0 grains of IMR 4350. and both stated the most accurate loads were the 57.0 loading. The 2824/2832 fps velocities listd were from 24 inch barrels in universal recievers...not even fired out of a real rifle...thats why we will never be able to achieve those published velocities. We have production rifles . Excess pressure is not your friend.

Gary
 
QuickLoad:

30-06 Springfield
Nosler Case (65.5gr H2O)
OAL: 3.33
IMR4350/60.0gr (That is a full(+) case)
22" barrel
69,000psi
2,935fps
 
These cases average 71.4 grains water. Also, these cases were not full upon loading, though the loads were compressed. I'm definitely going to reduce the load.

I HAVE checked my scale and it is accurate.
 
Thanks to Brian Pflueger for providing the QuickLoad numbers below using my actual case capacity data, a very consistent 71.4 grains water.

(QL) thinks that the nominal pressure would be about 55,000psi. With possible burn rate variance of ± 5%, it thinks the pressure could range from about 50 to about 60,000, all within SAAMI pressures. Even with a possible burn rate variation of 10%, the max pressure would be somewhere about 65,000.

QuickLoad predicts 2,789fps from a 22" barrel, using the powder burn rate of their tested samples. Low and high would be 2,680-2,996, with the +-5% variation.
Click to expand...

A couple of observations, statements, etc. in no particular order:

  • First, thanks again to Brian for running these calculations. It definitely helps me understand why I was able to "get away with" a load so much higher than published data (except for the one load on the Hodgdon web site).
  • With 59.0 grains, I chronograph a fairly consistent 2830 fps. QL's 2789 fps prediction for 60.0 grains suggests QL's predictions, including pressure, might be a bit low.
  • I only partially resize my cases. Closing and opening the bolt is always a bit "tight". Partial resizing undoubtedly explains the large case capacity. I note another poster used 65.5 grains water for his QL calculations versus my measured 71.4. His predicted pressure is 69,000 psi!
  • Undoubtedly, my larger case capacity kept the actual pressures lower than they might otherwise have been.
  • This load probably WOULD have MUCH higher pressures if I full length sized the cases as typically recommended for hunting loads.
  • While this load might be OK for a few hunting shots now and then, its sensitivity to case volume is definitely concerning. That reinforces the need to reexamine any load when using new cases, even if they are the same make, though maybe if the water volume is the same as the "old" cases the load need not be worked up again.
  • Though my cases don't really look like the overpressure pictures in my various manuals, there is no doubt they are beginning to show high pressure signs. That's enough for me to back off.
  • I had a previous box of Nosler cases that were a full 10% heavier than these! (case weight, not water weight). I full length sized those and they all failed after only 3-4 loads at 59.0 grains (with incipient case head failure). However, I never noticed any other signs of overpressure. Had I tried 60 grains with those cases…hmm
  • The minimal pressure decrease from seating the bullet deeper isn't sufficient to give me a warm fuzzy feeling about this load. Plus, my data shows I get the best accuracy with the bullet seated 10-30 mils off the lands.

Thanks to all those who commented. I've learned something!
 
Actually, your case capacity is independent of your sizing method. The brass forms to the chamber somewhere in the low 20,000 psi range. Regardless of how it's sized, it is back to the full size of your chamber (in your case 71.4gr) before the pressure peaks.
 
Musta' had a brain cramp. That makes perfect sense. So, case capacity is a function of the amount of metal in the case plus chamber dimensions. Variations can occur from (case) brand to brand, lot to lot and rifle to rifle, right?
 
Brian (& FlintLock)

A 55,000psi QuickLoad number is belied by the fact that Flint is experiencing 70,000psi(+) brass extrustion.
I trust the brass (especially Nosler brass) to tell the truth, and canot believe QuickLoad is that far off.
Something else is going on.
 
One of my theories is oil in the chamber or lube left on the brass.

I worked up some loads in my .243AI that showed extractor marks at loads that should have been below regular .243Win max. I had cleaned the barrel (brand new) and used more than normal cleaner and oil to make sure that I got any machining debris out. I was in a hurry and neglected to properly swab the remaining oil from the chamber. The extractor marks were scary, worse than the OP, but they went away completely even at much higher load levels after the oil was removed.

Of course, it's also possible that the OP has a case of compounding pressure increasing conditions that are simply beyond the abilities of software prediction, such as a slightly small bore, slightly large bullets, slightly hot powder and/or primers or any combination of those and more.
 
The only high pressure sign readily visible with my naked eye is the slight shiny spot from the ejector. True, there is the primer cratering, but I've seen FAR worse cratering on some .357 loads that were WAY over the limit, so this cratering didn't look bad to me.

What are you referring to as "brass extrusion", the circular machine marks on the cartridge base, picked up from the bolt face? Or do you see something else? Those marks are not readily visible with the naked eye.

We can eliminate lube on the outside of the case. I always hand wipe each case.

Oil in the chamber is a possibility, though I generally use only a slightly moistened patch. I did not wipe the bore and chamber before firing these loads.

I do recall measuring the bullet diameter and weight. They seemed right on to me.
 
flintlock.50 said:
The only high pressure sign readily visible with my naked eye is the slight shiny spot from the ejector. True, there is the primer cratering, but I've seen FAR worse cratering on some .357 loads that were WAY over the limit, so this cratering didn't look bad to me.

What are you referring to as "brass extrusion", the circular machine marks on the cartridge base, picked up from the bolt face? Or do you see something else? Those marks are not readily visible with the naked eye.

We can eliminate lube on the outside of the case. I always hand wipe each case.
Click to expand...

I had a few .243 loads one time that I got a little excited with. They looked just like yours where the brass had flowed into the extractor hole. Bolt lift was what I would call sticky. So I tried resizing and really had to crank the dies down to get head spacing right. Upon investigation I found the heavily extruded brass at the extractor, and I'm guessing ( never measured) that this brass that was sticking out caused my head spacing to be out of whack.
 
What are you referring to as "brass extrusion", the circular machine marks on
the cartridge base, picked up from the bolt face?
Click to expand...
Yes. The shiny mark is where the brass has been "plasticized" and shoved into the ejector hole -- and then the bolt face shears it off like a butterknife as it rotates open. Result: nice shiny new brass exposed.

You earlier mentioned that you'd had some incipient head separation after 3-5 loadings of 59gr/IMR4350. That generally comes from excessive headspace between the chamber and the case. Have you tried partial resizing to eliminate that excess -- to where the bolt "just closes" on the cartridge? That would reduce the running start that the case head gets before slamming into the bolt face.

(Then again, if the case had a real running start, I'd expect to see flattend primers. So I'm still uncertain as to how to explain lower-than-predicted velocities accompanied by high pressure signs.) :confused:
 
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