Why no pressure signs???

[DeauxJoe]

Loaded a ladder test for my .308 started at 40 grains and went to 47.5. Loading manual states max loads at 42.5 grains. I monitored my cases closely and never saw any pressure signs. It's looking like my most accurate loads are in the 46.5-47 range. What's y'all opinion about this?

H4895
168 Noslers
New Win brass
20 inch barrel

 

[turbo54]

Re: Why no pressure signs???

If you're not seeing pressure, you're good to go.

You might wanna check your casehead expansion to be sure.

 

[targaflorio]

Re: Why no pressure signs???

Would you like to post pics of your brass? I have never used h4895, but that seems like a long way past book. Do you have a chrono? Bolt gun? No difficult bolt lift? As mentioned, measuring expansion of the case is a better way to check than simply eyeballing.

 

[remaction]

Re: Why no pressure signs???

I'd second Turbo54's suggestion. I was working up some .223 Ackley loads earlier this fall (70 degrees) and was measuring the case head expansion in addition to the other "classic" signs (hard bolt lift, flattened priners, etc.). I noticed case head expansion of .0005" before getting the other signs (in this particular gun), so I stopped and backed down a bit as I didn't want issues if I used this setup in 95 degree temps.

Next time I work up loads, I think I'm going to fire some testing brass once using a proven middle of the road charge, and then work up the loads while measuring the caseheads throughout the testing process. This will give the brass a first time expansion and then I'll have a baseline for testing. The Ackley brass I was using had been fired before, so it was harder to get a baseline (similar diameter for each case), so I had to measure the casehead before and after firing each one.

 

[remaction]

Re: Why no pressure signs???

Also, I see you used new Win. brass. I'm entering dangerous territory here as I do not have hard data on this and it is mere speculation on my part so do not take this as gospel!

But I sometimes wonder that since new unfired brass has more springback, perhaps the hard bolt lift does not show up until the next, or the next firing. I'm sticking my neck out a bit here, but had an issue with a .284 Win one time and had worked up a good load and then subsequent firings had high pressure (no, the cases were not too long and up into the leade).

 

[DeauxJoe]

Re: Why no pressure signs???

Just measure the diameter of my fired cases? Ok I'll check some and yeah I'll take pics of my brass and you guys can tell me. But no I never saw any flatten primers all had nice round firing pin marks no heavy bolt lift or anything like that.

 

[targaflorio]

Re: Why no pressure signs???

You have to compare the measurements before and after firing. Hopefully, you didn't shoot it all?!

 

[TresMon]

Re: Why no pressure signs???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: turbo54</div><div class="ubbcode-body">If you're not seeing pressure, you're good to go.

You might wanna check your casehead expansion to be sure.</div></div>

Exactly.

and some of the manuals are REALLY conservative. But don't forget your Cold, blow and snow winter loads might be safe and then really hurt you or the riffle come August.

 

[bigwheeler]

Re: Why no pressure signs???

My older Hodgdon manual shows 43.5 as max with a sierra 168. The nosler manual gives the load with IMR4895 at 43.0 max. I sure would be careful to back
all the way down under 43 on your next can of powder. Something is way off.

 

[MALLARD]

Re: Why no pressure signs???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: TresMon</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: turbo54</div><div class="ubbcode-body">If you're not seeing pressure, you're good to go.

</div></div>

Exactly.

and some of the manuals are REALLY conservative. But don't forget your Cold, blow and snow winter loads might be safe and then really hurt you or the riffle come August. </div></div>

+1

 

[DeauxJoe]

Re: Why no pressure signs???

Well remember I am in south Louisiana so our cold, blow and snow days are in the 60's lol. In fact it is currently 66 outside right now.

So here are some pictures I put together and maybe you guys can help me out some more.

This is a group of factory federal loads with 168 Sierra MatchKings.


Uploaded with ImageShack.us

*Note the powder burns down the neck. I posted another thread about this but I couldn't get the pictures to come out. Whats ya'll take on this?


-this is a post fired Federal load.


Uploaded with ImageShack.us

-this is a win brass that is ready to be loaded but have never been fired.


Uploaded with ImageShack.us

This is a post fired win brass one of the hottest loads I fired. I measured the federal to see if there would be a lot of difference but as we can see not much.


Uploaded with ImageShack.us

-The only thing I noticed that was different from factory rounds and my reloads were these marks on top of the case. Can anyone tell me what they are?


Uploaded with ImageShack.us


-This was the one case that stood out, I don't know if you guys can see it but it looks as if the top of the case is almost crushed a little bit.


Uploaded with ImageShack.us

 

[DanSavage]

Re: Why no pressure signs???

Did you crimp the Winchester brass I hope. Also you want to be measuring the base of the case about 3/8" up from the bottom. I'd check the length of the case because it looks to mee like the neck is moving forward quit a bit and you may have to do some serious trimming (which isn't good for long case life.)

 

[TexIndian]

Re: Why no pressure signs???

Case trimming is something that crossed my mind too when looking at the pictures. That can cause just as much trouble as over-charging if they get too long. I assume your new brass was at min length when you started. How long are they now? Excessive growth can be a pressure warning, too.

remaction's remarks above tickled something in my memory about new brass sometimes not developing the same pressures during the 'fireforming' stage as when fired a second time. I'd sure drop down when trying the second firing of this brass. Reloading manuals can be very conservative but you seem to be getting way over the line with those loads. My pucker factor alarm is going off. Something ain't right here and that has a habit of coming back to bite you. What kind of gun are you shooting? Oversized chambers tend to develop less pressure, but still something ain't right here.

 

[DeauxJoe]

Re: Why no pressure signs???

I am shooting a B series m700 action with an aftermarket barrel but I'm not sure what kind. Mile High shooting put it all together for me. When I get back Monday I will measure the base of the brass and the COAL. I have another ladder test loaded at the same grains ready to go so I need to figure out this issue before I put this next one down the barrel.

 

[bigwheeler]

Re: Why no pressure signs???

Those are just the factory crimp marks, a lee factory crimp die leaves similar marks.

 

[X-fan]

Re: Why no pressure signs???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: turbo54</div><div class="ubbcode-body">If you're not seeing pressure, you're good to go.

You might wanna check your casehead expansion to be sure. </div></div>

This is going to ruffle some feathers, but....

No offense intended, but nothing could be further from the truth.
You absolutely can have extreme pressure without seeing it.

I own both an old Oehler 43 and a brand new CED (RSI) pressure trace. My budds and I have tried numerous case measurements against the strain gauge (buddy is a machinist). In EVERY case the measurement method was an utterly unreliable system for determining max pressure.

The only somewhat reliable pressure indicator is velocity.

Hodgdon shows a 168HPBT over 43.5gr of H-4895 as max (50,000 CUP)so I am positive 47grains and the Nosler are way over pressure.

I would like to see a close up picture of the case head.

Here is some reference info for the scoffers.
http://www.shootingsoftware.com/ftp/dbramwell%20july%2019%2004.pdf

 

[DeauxJoe]

Re: Why no pressure signs???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: X-fan</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: turbo54</div><div class="ubbcode-body">If you're not seeing pressure, you're good to go.

You might wanna check your casehead expansion to be sure. </div></div>

This is going to ruffle some feathers, but....

No offense intended, but nothing could be further from the truth.
You absolutely can have extreme pressure without seeing it.

I own both an old Oehler 43 and a brand new CED (RSI) pressure trace. My budds and I have tried numerous case measurements against the strain gauge (buddy is a machinist). In EVERY case the measurement method was an utterly unreliable system for determining max pressure.

The only somewhat reliable pressure indicator is velocity.

Hodgdon shows a 168HPBT over 43.5gr of H-4895 as max (50,000 CUP)so I am positive 47grains and the Nosler are way over pressure.

I would like to see a close up picture of the case head.

Here is some reference info for the scoffers.
http://www.shootingsoftware.com/ftp/dbramwell%20july%2019%2004.pdf </div></div>

When I get in Monday I will get some pictures of case heads and tri to measure a few in addition to the other stuff. I was hoping to shoot my other ladder Monday afternoon. I will bring my chrony out. Is there a specific fps I should not go over?

 

[turbo54]

Re: Why no pressure signs???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: X-fan</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: turbo54</div><div class="ubbcode-body">If you're not seeing pressure, you're good to go.

You might wanna check your casehead expansion to be sure. </div></div>

This is going to ruffle some feathers, but....

No offense intended, but nothing could be further from the truth.
You absolutely can have extreme pressure without seeing it.

I own both an old Oehler 43 and a brand new CED (RSI) pressure trace. My budds and I have tried numerous case measurements against the strain gauge (buddy is a machinist). In EVERY case the measurement method was an utterly unreliable system for determining max pressure.

The only somewhat reliable pressure indicator is velocity.

Hodgdon shows a 168HPBT over 43.5gr of H-4895 as max (50,000 CUP)so I am positive 47grains and the Nosler are way over pressure.

I would like to see a close up picture of the case head.

Here is some reference info for the scoffers.
http://www.shootingsoftware.com/ftp/dbramwell%20july%2019%2004.pdf </div></div>

No offense taken. You're probably right, and he probably IS overpressure according to SAAMI. However, 99.999% of reloaders don't have pressure trace instrumentation, and 90%+ don't have a chrony. They rely (rather successfully, I might point out), on bolt lift, primer flatness and ejector marks/swipes on the casehead. In fact, I contend that measuring casehead expansion is a rather "advanced" loading technique relatively few know about and use. These methods have served tens of thousands of folks well.

If the bolt lift is ok, primers aren't seriously flat (more an indication of HS than pressure), and you don't have ejector marks, there is a very small likelihood you're in a "damaging overpressure" zone. Good casehead growth numbers make the risks even smaller.

That all said, his charge weight does indeed sound HIGH! How much confidence do you gave in your scale????

 

[former naval person]

Re: Why no pressure signs???

Measuring case mouths only tell you what the fired diameter of the case mouth is. Nothing about pressure. Measure the base of the unfired case just ahead of the cannelure before firing. When you start the work up, measure the case each time you fire it at the same place. Go up in .3 grain increments. When the expansion reaches .001 at the same point...STOP increasing the charge. Fire several more in that same case at that charge. The expansion should remain the same throughout multiple firings of that case. If it continues to expand at that charge, back off .5 grains. and reload and refire a new case at that charge weight. If it stays at .001 without further expansion, you are GTG as far as maximum charge weight is concerned. (If you continue to increase the charge once it reaches .001 and get to the point that it continues to expand, the primer pockets will get loose quickly and the case is toast.) All that does not mean that the MAX charge determined is anywhere near the most accurate load. It just determines the point at which you can either start buying new cases, or spending your cash on more bullets and powder. JMHO

 

[X-fan]

Re: Why no pressure signs???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: turbo54</div><div class="ubbcode-body">
No offense taken. You're probably right, and he probably IS overpressure according to SAAMI. However, 99.999% of reloaders don't have pressure trace instrumentation, and 90%+ don't have a chrony. They rely (rather successfully, I might point out), on bolt lift, primer flatness and ejector marks/swipes on the casehead. In fact, I contend that measuring casehead expansion is a rather "advanced" loading technique relatively few know about and use. These methods have served tens of thousands of folks well.

If the bolt lift is ok, primers aren't seriously flat (more an indication of HS than pressure), and you don't have ejector marks, there is a very small likelihood you're in a "damaging overpressure" zone. Good casehead growth numbers make the risks even smaller.

That all said, his charge weight does indeed sound HIGH! How much confidence do you gave in your scale???? </div></div>

The reason I mention this is there is a tendency among quite a few experienced shooters on this site to place absolute trust in the case head measurement system...Even when they are drastically exceeding pressure tested data and velocity.

I have been around long enough to see several perfectly good bolt rifles blow with what seemed like perfectly good loads.
I fired one of those harmless looking loads (blueprinted Remington) and the bolt opened like butter....I then carefully examined the case. There was the slightest wisp of an extractor mark and a normal slightly flattened primer.
I near shit when I looked at the laptop!
The pressure curve ended at 80kpsi(the peak of my equipments abilities) and was headed north!

A rifle will not blow the first time you fire one of those, but what happens the hundredth...Or the thousandth time?

FWIW I always make my equipment available at the local range...I go so far as to make the local online guys aware of the capacity to use my equipment should they live close enough.

I figure if a guy wont do that he doesn't deserve to own it in the first place.

Peace

 

[Fester47]

Re: Why no pressure signs???

This is why I like to shoot over a crono when I do a ladder test. When the SD and the velocity is close to what I want then and I don't have any pressure sighns then I stop. No reasone to try to see when she blows.

 

[DeauxJoe]

Re: Why no pressure signs???

How do I figure out where my MV needs to be?

 

[Fester47]

Re: Why no pressure signs???

(How do I figure out where my MV needs to be?)

The best to tell where MV needs to be is in the top MV Nod.

Other people's reloading post. Reloading books. Compare to factory ammo MV. Common sense, if it looks like it is going to fast for that caliber and weight of bullet then it might not be safe. Stay within reloading guides and you good judgment. Just compare apples to apple as close as you can.

Speed kills your barrel and sometime isn’t worth it

 

[X-fan]

Re: Why no pressure signs???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: DeauxJoe</div><div class="ubbcode-body">How do I figure out where my MV needs to be? </div></div>

To add to Bryce's comments:

Here for pressure tested data
http://data.hodgdon.com/cartridge_load.asp

Input your cartridge and cross check your bullet weight.

You also need to make a minor correction for your short barrel....Not sure what to allow for the 4 inches....The 308 is not my thing, but I would guess 75 fps?
Someone else should chime in on that one.

 

[TexIndian]

Re: Why no pressure signs???

I use my chrono during testing just to see where I'm at in regard to other published loads. If most data shows 2600 fps with a max load and I'm getting 2850 with the same basic components, all my alarm bells are going off.

I've seen strong guns shoot over-pressure loads with no apparent problems. But each time they fire that load the gun gets a little weaker from stresses it wasn't designed to handle, IMO. It's just a matter of time before something gives. It's no different than taking a brand new pickup and driving hell bent for leather over the roughest roads you can find. It may not fall apart immediately but you are shortening its life for sure.

 

[Muttt]

Re: Why no pressure signs???

It sounds to me like a person new to reloading is just pushing the limits up into the "DANGER" range just because he can, without enough knowledge to even know what pressure sign really are. I say this because I've noticed some simple things in this thread.

1. OP had no idea what the "factory crimp" mark where
2. OP has no idea what the case head is. He was asked to post pics and he posted pics of the wrong end.
3. OP is wondering about the powder burns on the necks

The books where written by people with tons more knowledge than us. The mins and max are there for a reason.

 

[DeauxJoe]

Re: Why no pressure signs???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Muttt</div><div class="ubbcode-body">It sounds to me like a person new to reloading is just pushing the limits up into the "DANGER" range just because he can, without enough knowledge to even know what pressure sign really are. I say this because I've noticed some simple things in this thread.

1. OP had no idea what the "factory crimp" mark where
2. OP has no idea what the case head is. He was asked to post pics and he posted pics of the wrong end.
3. OP is wondering about the powder burns on the necks

The books where written by people with tons more knowledge than us. The mins and max are there for a reason. </div></div>

Mutt I by no means disagree with you about my lack of knowledge. As far as pushing the bound because "I can" that is simply not the case. I have read up on reloading a lot and monitored my cases closely through my entire ladder test. When I got through it I knew something was wrong that's why I came here to tap into the knowledge of people with far greater loading experience than me. I respect reloads and wouldn't do that on purpose.

 

[DeauxJoe]

Re: Why no pressure signs???

I was able to do more testing today a few results for you guys to evaluate.
I measured my case heads and I see to be gaining about .006. I also seem to be gaining about the same amount in COAL. It seems pretty normal when compared to factory cases.

I took the second half of my ladder test and shot it over the chrono. @ 45 grains I was @ 2715 fps which was right around the max my load data gave me. So with that being said I can only imagine how hot my last loads were. Question here is 45 grains is still 1.5 grains higher than the max grains suggested. Which should I go by?

 

[longshooter]

Re: Why no pressure signs???

I don't know if it's been mentioned, but you need to verify your powder drops are not light. Verify your scale accuracy with check weights.

 

[DeauxJoe]

Re: Why no pressure signs???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: longshooter</div><div class="ubbcode-body">I don't know if it's been mentioned, but you need to verify your powder drops are not light. Verify your scale accuracy with check weights. </div></div>

Good catch and yes that is something I have been doing.

 

[longshooter]

Re: Why no pressure signs???

You can probably add 100fps to your load to make up for the short barrel. Therefore, you're probably 2 grains and 100fps faster than book.

 

[Clark]

Re: Why no pressure signs???

I never worry about pressure* in a 243, just the effects of pressure on brass life.

I work up to the threshold of short brass life, and then back off a 4% margin in powder charge for my own loads for one rifle. Vernon Speer in 1956 wrote that he backed off 6% for writing load books.

I find that measuring the extractor groove all the way around with a dial indicator before and after firing is a better indicator than either looking for primers to fall out or feeling the effort to insert the next primer.

* If I knew and loaded based on actual absolute pressure, it would introduce a number of errors in the process of developing a personal hand load. It is important, however inaccurate, in commercial ammunition, starting loads, and recipes for beginners.

 

[X-fan]

Re: Why no pressure signs???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: longshooter</div><div class="ubbcode-body">You can probably add 100fps to your load to make up for the short barrel. Therefore, you're probably 2 grains and 100fps faster than book. </div></div>

This is what I am thinking.

DeauxJoe I think you are there and then some...As you are a beginner I would back it off a bit more and give yourself some headroom for error.
50fps wont make any difference.

Shoot some ladder tests at 200 (or more) so yards. generally speaking the overly hot loads don't shoot anyway.

 

[Mike Casselton]

Re: Why no pressure signs???

Start over. Don't work your way down into the known safe area. You work your way up and stop when signs indicate max pressure, then you go back a bit more to get into the actual safe zone.

If you have a chronograph, load in .3 gr increments and load at least five per charge. As you move away from the starting loads, you chronograph will indicate a steady increase in velocity. (Yes, there will be some errors and some totally over and under where they should be velocity-wise)When you reach a point of diminishing returns, you will notice the .3gr increase in powder didn't give you the normal velocity increase. Next one will do the same. (In fact if you graph it, you can pinpoint the exact place where you should stop.)Each successive increase will show the same lesser return. don't be surprised if sudenly you get a tremendous increase in velocity. That means you are WAAAAY over pressure.

For my loads, I chronograph them and find the velocity that gives me the best ACCURACY, as long as the loads remain safe pressure-wise. Guess what, most bullets of the same weight will shoot well at this same velocity. (There are some guns that will shoot only one bullet well, no matter what the velocity) I care way more about accuract than velocity.

There is plenty more to learn, but starting from the top and going up WILL eventually put you in the hospital...

 

[DeauxJoe]

Re: Why no pressure signs???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Mike Casselton</div><div class="ubbcode-body">Start over. Don't work your way down into the known safe area. You work your way up and stop when signs indicate max pressure, then you go back a bit more to get into the actual safe zone.

If you have a chronograph, load in .3 gr increments and load at least five per charge. As you move away from the starting loads, you chronograph will indicate a steady increase in velocity. (Yes, there will be some errors and some totally over and under where they should be velocity-wise)When you reach a point of diminishing returns, you will notice the .3gr increase in powder didn't give you the normal velocity increase. Next one will do the same. (In fact if you graph it, you can pinpoint the exact place where you should stop.)Each successive increase will show the same lesser return. don't be surprised if sudenly you get a tremendous increase in velocity. That means you are WAAAAY over pressure.

For my loads, I chronograph them and find the velocity that gives me the best ACCURACY, as long as the loads remain safe pressure-wise. Guess what, most bullets of the same weight will shoot well at this same velocity. (There are some guns that will shoot only one bullet well, no matter what the velocity) I care way more about accuract than velocity.

There is plenty more to learn, but starting from the top and going up WILL eventually put you in the hospital... </div></div>

Gret advice thanks. When you fire your rounds do you fire one of each load and then come back around or do you fire all of one load then fire the next diet of loads?

 

[Mike Casselton]

Re: Why no pressure signs???

Firing one of each load won't tell you much. Problem is that even though carefully weighed, sometimes a loaded round will be totally off the scale (or under it) in regards to pressure. The only way to know for sure is using pressure test barrels.

Get some graph paper, create a velocity/powder amount scale on it and using a chronograph, chart your progress. Make the chart in 25 fps increments and in whatever your powder differences are (ie:.3 or .5 gr or whatever you use) If you fire near the upper load and you see the drop in velocity gains referred to above, there is no need to get into the danger zone as far as pressure is concerned.