Is this load too hot?

[Robinhood]

Darkker, For the sake of conversation... by your own admission the ejector hole impression and swipes have no meaning whatsoever. Only the trace will tell. Is this correct?

[bigedp51]

Brass flow into the ejector and measuring expansion just above the extractor groove tells you how hard the brass is and its elastic spring back limits.

Meaning softer brass will flow into the ejector hole at a lower pressure and this tells you it time to back off no matter the actual chamber pressure.

One problem with measuring expansion above the extractor groove is the thickness of the flash hole web will add strength to the base of the case.

The left case below with the thinner flash hole web will show more base expansion and loose primer pockets before the case on the right.

https://i.imgur.com/cYeTsDp.jpg


Below the Remington case will show brass flow into the ejector before the Lake City case.

How Hard is Your Brass? 5.56 and .223 Rem Base Hardness Tests

http://bulletin.accurateshooter.com/2014/05/how-hard-is-your-brass-5-56-and-223-rem-base-hardness-tests/

http://accurateshooter.net/Blog/brasstest03.png
(http://bulletin.accurateshooter.com/2014/05/how-hard-is-your-brass-5-56-and-223-rem-base-hardness-tests/)

[darkker]

Do you think this is an essential tool like a chronograph for reloaders? Depends on what you are trying to accomplish. For general loading, not if you remember the fundamentals. SAAMI load data is all minimum bore, groove, chamber spec. So a mass produced thing will be sloppier and slower. Book data has MAX velocity and charge weight. If you reach either one of those, regardless if you have reached the other, you have already(most likely) reached book max pressure. If you want to see how a powder behaves, such as with the progressive powders, then it is critical to be able to take advantage of what they have to offer. My loads in the Creed with one is very nearly max book speed, but running around 12,000 psi below SAAMI MAP. Can't accomplish that without pressure measurement equipment.


Darkker, For the sake of conversation... by your own admission the ejector hole impression and swipes have no meaning whatsoever. Only the trace will tell. Is this correct?
Yes, and No. For simplicity sake, yes.

Using them as a "Sign" with no way of being able to measure pressure, is not directly useful because it isn't connected to any one thing; It's more like an arbitrary number. Think of a crazy homeless guy on the street: If you ask him what time it is, and he answers you with a rant about something "they" are putting in the water. He indeed did tell you something, but was it connected to what you wanted to know? Was it helpful to your cause?

Here is a good example of that:

http://i78.photobucket.com/albums/j84/Darkker13/Mobile%20Uploads/IMG_20160124_145616_zps0jwkwsb5.jpg


Relying upon the "signs" shown in the picture, normal people would say that the load was WAAAAYY to hot, yes? Blown primer and ejector mark is indeed a "sign", but a sign of what? That load was between 50-55K psi. The problem with it had nothing to do with pressure, it had to do with that Federal case having a soft head. Federal GMM ammo is partially as consistent as it is because of softer cases, they obturate very quickly to seal to the chamber. Good for accuracy, not good for long brass life; or being able to accurately measure case head expansion. Unless you know this, you don't know it; and it adds a further complication to what you think the "signs" are telling you.

In some instances there is no good data available(wildcats, new cartridges, etc), so the only thing you have to use as a judgement of pressure, are signs. But with a handful of unknown variables, choosing one on, for lack of a better word, faith, doesn't get you an understanding of what is actually taking place. Most folks don't have a very good understanding of what SAAMI MAP is anyway. So what are they asking for if they want to know if it is "too hot"? It could be:
a) Well.... It didn't blow-up.
b) SAAMI MAP
c) Book tested pressure
d) Something else

Most of us know that with mass production, sometimes things slip past QC regardless of intent. If the average Joe saw the case above, could he use signs for anything helpful to not repeat that event? Would it tell him if he had a bad case, would it tell him what his pressures were, would it tell him how much if any he needed to back off the load, that his powder burning rate had shifted? Signs can't reliably answer any of those questions, even though they told him something.

Cheers

[Robinhood]

Excellent feedback Darkker. Have you heard that fluoride is a byproduct of pesticide manufacturing process and is toxic?

[darkker]

Have you heard that fluoride is a byproduct of pesticide manufacturing process and is toxic?

Naw, that little fella is just your typical monatomic anion of element #9 on the periodic chart.:cool:

The exciting news for all the "naturalists" in this state, that like to lay out on and take home granite. Uranium would qualify as Vegan.

[JASmith]

I have used the Pressure Trace on just one cartridge and rifle so far -- the 6.5 Grendel in a TC Encore.

The first thing I discovered is that the lug under the chamber significantly reduces the strain seen even at the top of the chamber where my gage is located.

I therefore tested close to ten loads from two different powder manufacturers to calibrate. Now when the system says "50 ksi" I know that it means my load has a good chance of being within about 5% of that pressure when tested in the powder manufacturers' pressure breeches.

It dies NOT mean that actual pressure is 50ksi, only that the number has a good chance of being consistent with published data.

BOTTOM LINE: When possible, test against known loads before assessing your own loads. If you have a wildcat, try at least to pressure test with known loads in the parent case.

[DanSavage]

With Lapua brass your probably a little warm. With tight headspace and a short throat, I ran at 41-42 gr. IMR 4064 with 178 amax reaching 2800 fps. Using a 26" Shilen Select Match barrel.With Lapua brass.

[DanSavage]

I have run 44gr imr 4064 with a 175 SMK but it was in Winchester brass,, good load.

[darkker]

The first thing I discovered is that the lug under the chamber significantly reduces the strain seen even at the top of the chamber where my gage is located.


Yes, that gets cautioned against by the folks at RSI, you have to know exactly what the dimensions of the barrel outter diameter are. A lug will mess with that pretty good.:(
We have used Ruger's or Savages without a nut on short action cartridges. You can also jump to the SAAMI website and they list all the various mfgrs part numbers for reference ammo. So you can call whichever you prefer and order tested reference ammo if you wish for a good calibration.

[bigedp51]

Excellent feedback Darkker. Have you heard that fluoride is a byproduct of pesticide manufacturing process and is toxic?

In the mid 1970s Paul Harvey on his radio program said "Research scientists have discovered that Orange Juice causes cancer in gay rats"

Are you saying these rats may have ingested fluoride or do you and Dakker live in Colorado and are on a John Denver rock mountain high.

[bigedp51]

Excellent feedback Darkker. Have you heard that fluoride is a byproduct of pesticide manufacturing process and is toxic?

In the mid 1970s Paul Harvey on his radio program said "Research scientists have discovered that Orange Juice causes cancer in gay rats"

Are you saying these rats may have ingested fluoride or do you and Dakker live in Colorado and both of you are on a John Denver rocky mountain high.

[m12lrs]

i think i will stick with sticky bolt lift and condition of the brass to tell me where my max is. It has worked for me for over 40 years. of course i am not one of those shooters seeking max velocity.

I am not one of those people who believe everything some computer spits out.

[darkker]

Just depends on what you want to call "max", and what you are after.
Assuming there is no soft brass, or other issues in the burning curve; my work with the 308 *TENDS* to show stiff bolt lift when you are above 70,000 PSI.
I also don't run full pressure on most things anymore. I'm more of a light and tight(groups) shooter. Keeps components lasting a loooooong time.
Still running some brass with heastamps from the 60's!

[Deadshot2]

Just depends on what you want to call "max", and what you are after.
Assuming there is no soft brass, or other issues in the burning curve; my work with the 308 *TENDS* to show stiff bolt lift when you are above 70,000 PSI.
I also don't run full pressure on most things anymore. I'm more of a light and tight(groups) shooter. Keeps components lasting a loooooong time.
Still running some brass with heastamps from the 60's!

I went down the rabbit hole of trying to see how much speed I could get out of my various rifles/calibers. Didn't break anything but I did learn that when I stuck to working UP my loads from a modest start I usually found a load that was super accurate and had more than enough speed to get it to the target at any distance I was interested in. Any more powder, speed, pressure, was overkill and also a pain in the butt when it came to hot weather.

I figure that if I need to reach out farther I'll just get a rifle chambered with a cartridge designed to shoot that far.

[darkker]

Can have some challenging fun with slower moving stuff sometimes. Couple years back MZ5 came up and we did some shooting to a mile. My 308 was changing those barrel lids at something silly like 850fps.
Makes reading wind a real trick!

[bearcatrp]

I figure that if I need to reach out farther I'll just get a rifle chambered with a cartridge designed to shoot that far.
Best answer right there. Reason why I sold my 6.5 CM and picked up a 338LM.

[Savage11]

Somewhere between the starting load and the maximum will show the best accuracy, I usually end up with a load that is about 2 grains off max, very safe, very accurate.
Last hunting season I tagged a nice buck and a huge black bear with my 308, both were taken with 165 grain bullets, one shot each.
The 308 doesn't have to be loaded to dangerous levels to be very effective and accurate.
When I get the urge to reach out there , I shoot 300 mag or borrow a buddy's 338 Lapua.
The 308 is not one of the above, when used as designed it will fill the freezer and still have enough in the tank to hit gongs at respectable distances.

[wbm]

Somewhere between the starting load and the maximum will show the best accuracy, I usually end up with a load that is about 2 grains off max,


Years ago one of the techs at Sierra suggested that if you start 2 grains below maximum with their bullet data more often than not you will end up with a very accurate load and I have found that to be true more often than not.

[Savage11]

Years ago one of the techs at Sierra suggested that if you start 2 grains below maximum with their bullet data more often than not you will end up with a very accurate load and I have found that to be true more often than not.


I have found that two grains below max works well for me, I do have some loads that are book max and find no difference in hunting situations.
i am saying that trying to make a 308 into a 300 mag isn't possible.