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

[flintlock.50]

Thanks Brian. I'll PM you tonight.

[flintlock.50]

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!

[gwpercle]

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

[mehavey]

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

[flintlock.50]

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.

[flintlock.50]

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.

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!

[Brian Pfleuger]

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.

[flintlock.50]

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?

[243winxb]

A rifle chamber has a volume running from bolt face to when the bullet seals the bore. When more mass/weight is placed in the volume, pressure & velocity goes up. Seen a post where some extra heavy 308 brass caused loose primer pockets using the starting load. http://www.thehighroad.org/showthread.php?t=501655

[Brian Pfleuger]

Originally Posted by flintlock.50

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?

That's correct.

[mehavey]

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.

[Brian Pfleuger]

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.

[flintlock.50]

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.

[Kimber84]

Originally Posted by flintlock.50

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.

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.

[mehavey]

What are you referring to as "brass extrusion", the circular machine marks on
the cartridge base, picked up from the bolt face?

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.)

[flintlock.50]

The Nosler cases that failed were nearly 10% heavier than the ones I'm using now. They weighed 204 grains. My current cases are 185-186 grains. Also, I full length resized those cases. That gave them more room to stretch upon firing. I currently only partially resize my cases.

After a few firings, I noticed a ring around the case 0.35" from the base. Upon examination with a strong magnifying glass, I saw that the shiny ring was actually a groove. I used a piece of bent wire to feel inside the case and could also detect a groove on the inside. None of these cases ever leaked because once I saw the ring, I discarded the entire box. Not happy with only getting 3-4 shots out of Nosler cases, I weighed the cases trying to figure out what had happened. That's when I found out that this particular box was quite heavy compared to my other Nosler cases.

My bolt was replaced a few years ago after I had 3 or 4 primer perforations. The jet of hot gas coming out of the perforation made gouges in the bolt face. These were VERY old Federal primers that failed with moderate loads. All the failures were at the edge. I had to send the rifle back to Remington to get the bolt replaced because Remington told me they needed to fit the bolt to the rifle to get the proper head space.

I looked at the bolt face with a strong magnifying glass tonight. It does show very tiny specks of brass on much of the face. I didn't see any obvious brass that had been sheared off at the ejector pin. The explanation of the shiny spot being caused by brass extruding into the ejector pin then being sheared off when the bolt is opened certainly makes sense.

I looked at other cases (a variety of loads, some factory) to see if they show the circular machining marks seen on the ends. Some show no marks at all. Others show the beginnings of circular machining marks.

I also ran a patch into the chamber tonight. (I had not cleaned the chamber and bore on Sunday when I shot the five 60 grain shells.) It came out slightly blackened, but not oily. I would have been very surprised if it had come out oily.

I think this will have to remain a mystery. I certainly love the load's accuracy, but I have no desire to push the pressure to the limit. I've also learned a great deal from comments on this forum. But then, that's the whole point of this forum and web site anyway.

Thanks!

[Shawn2571]

Yeah 57 grains is the magical spot for 4350 in the 30/06 with 165 grainers. 60 grains is too much

[HiBC]

One other thing to realize.When you do extrude brass back into the ejector hole,the case is held tight to the bolt face as the shoulder is fire formed to the chamber.
The hole for the ejector has sharp edges.You see a shiny spot because your bolt has sheared off the extrusion as you opened the bolt.
Don't put stock in the fact your fingernail does not catch on the extrusion.
I agree,extrusion is a serious sign,not to be ignored.

I do agree that IMR 4350 and a 165 or 168 gr Accubond is a great 30-06 combination.

But its great loaded to reasonable pressures.One way I watch for my rifles max,among other things,is diminishing velocity return for an increment of charge weight.
Like,maybe for four steps of 1/2 gr increase,I get 50 fps of gain.Then a step of 1/2 gr only gives 30 fps. That's hitting the wall.
And pressure increase is spiking because its outrunning the bullet.

Not all chronographs are precisely calibrated. Same with powder scales.
Either can mislead.

I have found if the sun is low,the shadows the chono reads are fickle,and results are not trustworthy.

After work,sundown at the range is not the best chrono time.

[F. Guffey]

When a reloader starts worrying about pressure I always suggest the invent in a few gages. I have a Pratt & Whitney electronic gage that measures down to .000005", that is annoying, so I removed the electronics and then installed a precision dial indicator. And now I have one of the smoothest running height gages ever made and it does not hurt that is weight 35 pounds.

I would suggest a reloader learn to measure before and again after meaning the reloader needs to learn to measure the diameter of the case head before firing and again after. Starting out the reloader needs to understanding what it means to compare. Normal case head expansion, when compared with factory ammo is .00025". that measurement is taken from a new/factory loaded case. The second firing of the case if close to factory loading should not expand more than .00025".

If the reloader discovers the case head expansion is .001" on the first loading he should expect the case head shortened from the cup above the web to the case head, he should expect the primer pocket to expand, he should expect the flash hole to expand.

Reloaders skip the discipline of measuring before and again after when it comes to case head expansion, I am not surprised when they believe some cases have soft brass.

And then there are slow barrels and slow barrels, I have a very discipline reloaders that can add an additional 2 grains over maximum with no signs of pressure, hew could have a barrel that is larger in diameter than most barrels, he could have a chamber that is a few thousandths longer from the shoulder to the bolt face than a go-gage length chamber or he could be using old Winchester brass.

He had one rifle that shot one hole groups but he had to reduce the powder to cut down on case head expansion. I suggested he not mess with it so he sent the rifle back. He no longer has the problem with pressure signs and he no longer gets one hole groups.

F. Guffey

[Don Fischer]

Is the OP even still alive? Boy this is old! One thing I noticed he said was that he partial sizes and leaves the case tight in the chamber an loading and unloading is a bit sticky because of it. Always been my though that one of the first sign's of pressure is a sticky bolt. He could have sized away to clue he needed. Lot of guy's like him around, they want the case fitting the chamber to well, they want to feel the neck rub. Well fine, there goes my best sign of pressure, a sticky bolt! My next sign it the ejector mark, he's seem's to have that. To presume a flat primer is a sign, it has to look like it was pored into the pocket. Some primer's that appear flat are not much more than soft cups. If the primer is a sign there should probably be some gas leakage around the edge of the primer. With the way he's sizing case's I could see how he'd easily miss a sticky bolt.

[Unclenick]

…And, note there is no longer a photo with OP, probably thanks to the Photobucket policy change, so it's impossible to see what he actually had to get the full context. IMHO, the thread should be dead for that cause anyway.

I'll point out that all published velocities where no gun is specified, like with commercial ammunition and Hodgdon's data, are fired in SAAM standard pressure and velocity test barrels. These have chambers that are minimum size to within half a thousandth of an inch, a barrel with a specific cross-sectional area, and they have a standard length, which, for rifle cartridges, is most often 24 inches (see the SAAMI standard to check the length for your cartridge). Additionally, the cartridges are manipulated to be sure the powder falls over the flash hole for firing, the position that produces the highest pressure and velocity just like the minimum chamber does. The tests are done within a specified temperature range. If your gun doesn't match theirs and the handling and conditions don't match theirs, you typically won't get the same velocity they did. It's just a reference point.

Meanwhile, given the missing images, I think I'll put this one to sleep.