Help reading pressure signs on fired brass

[harry_x1]

Hi Friends,

I regularly shoot 338 lapua from a 26 inch barrell with 300 grain bergers, loading 90 grain H1000. Velocity ~2763 fps.

Attached are some pictures of fired brass. Can some experienced reloaders help me read any pressure signs from these pictures ? Rifles shoots perfectly but want to make sure I am not in too much of a danger zone.


Thanks
Harjeet

 

[B y r o n]

Just looking at the case heads it doesn't look like there is anything in the extreme range. I don't see any ejector marks or swipes from the case stuck in the chamber when the bolt is rotated. How did things feel when you went to chamber the next round? Did the bolt lift seem difficult? I'd ask about the recoil but not knowing what brake/barrel combination or your level of feel for recoil energy that would be pointless.

 

[TheOfficeT-Rex]

Primers look pretty flat, and like they may have a slightly cratered strike.

ETA: GRT puts that load on default settings at almost 69k psi, FWIW.

 

[harry_x1]

Just looking at the case heads it doesn't look like there is anything in the extreme range. I don't see any ejector marks or swipes from the case stuck in the chamber when the bolt is rotated. How did things feel when you went to chamber the next round? Did the bolt lift seem difficult? I'd ask about the recoil but not knowing what brake/barrel combination or your level of feel for recoil energy that would be pointless.

Its an AI AXMC and we fired rougly 50 rounds...unfortunately I was just spotting, but the shooter tells me that he was experiencing heavy bolt lifts in approx ~50% of the rounds. I had taken initial 5 shots and did not experience heavy bolt lift on first 5 shots, seems the heavy bolt lift started around 10-15 shots in.

Recoil was very manageable.

 

[nn8734]

Sounds like the load is slightly over pressure. Back off .5g and see if it still performs after a string of 15-20 without any heavy bolt lift

 

[whatsupdoc]

I see some ejector marks, your pictures are not great but never the less if you have hard bold lift you need to
reduce the load. Test with some factory ammo to see if bolt lift improves.

 

[supercorndogs]

I see ejector marks and swipes on a lot of brass. Especially coupled with heavy bolt, if I wanted the brass to last I would want to figure out if the ejector marks are from headspace. Like you get in your first firing with a lot of belted cases, or high pressure. The few swipes I see, and the report of heavy bold lift makes me think pressure. And that the brass wont last long on that corse.

 

[redbullitt]

Id say its not for sure a pipe bomb, but looks pretty hot. Id back off and see if you can get things looking a bit more tame.

That heavy bolt lift definitely is a big red flag. Combine that with the flat primers and i see a very notable sign to lower the charge.

 

[straightshooter1]

Hi Friends,

I regularly shoot 338 lapua from a 26 inch barrell with 300 grain bergers, loading 90 grain H1000. Velocity ~2763 fps.

Attached are some pictures of fired brass. Can some experienced reloaders help me read any pressure signs from these pictures ? Rifles shoots perfectly but want to make sure I am not in too much of a danger zone.


Thanks
Harjeet

There's definite signs of overpressure, being the flattened primers and mainly the ejector imprints being left on the base.

 

[ArTeeKay]

Take it back a couple percent. Rifles rarely shoot at their best at their limits, and so you're likely to see both an improvement in accuracy and long term performance if you dial things back some. Most everything regarding specifics of pressure signs has been touched on already, otherwise.

 

[John Glidewell]

 

[Huskydriver]

90 grains is a very stiff load.

 

[Huskydriver]

For reference with a factory ai 338 barrel and an axmc I could only ever get 84 ish grains safely.

Ymmv

 

[redbullitt]

The speed is likely not doing you any favors. As said above, usually rifle is not doing its best work pushed up there. it's risky with component variations and that nice lapua brass will get retired way way to quick for my liking lol.

 

[Yondering]

There are some indications that might be high pressure (primarily the heavy bolt lift and hot load), but the primers aren't one of them. Without knowing headspace/bump (or if this is the first firing, etc) or what primers were used, one can't accurately say those flat primers indicate high pressure. It could just as easily be excess headspace causing flat primers and ejector marks, and a rough chamber causing heavy bolt lift.

Backing off is always a safe bet, but I don't see enough evidence here to say for sure that it's needed or if there are other things to fix first.

 

[Doom]

Heavy bolt lift is a reliable indication of overpressure and is much more reliable than looking for ejector marks or flattened primers. Your velocity is significantly higher than Hodgdon or Berger. You can expect these cases to last a very small number of reloading.

 

[OkieMike]

View attachment 7990876

Im going to say first that I agree with you.

But I'm also going to say that I have found Berger load data to be extremely "conservative."

And I hate to use the word conservative because I feel a lot of load data tends to deserve the label "candy ass" more than conservative.

I'm not saying the OP should continue shooting 90 gr of H1000... I'm saying he should back off to a charge that gets rid of heavy bolt lift, ejector swipes, smiley faces, and flattened primers while giving good accuracy... And if it's over Berger's listed max, then it's up to him to decide if it's still safe.

In my opinion, if lawyers and insurance underwriters designed roller coasters they would all be on a straight, level track 10 feet long and powered by a gondolier with a push pole.

Note: John I wasn't trying to pick on you or your post specifically. My point was that manufacturers don't just answer to their customers... The lawyers and insurance guys are always there wagging their fingers and saying, "Just to be on the safe side..."

Mike

 

[Doom]

Im going to say first that I agree with you.

But I'm also going to say that I have found Berger load data to be extremely "conservative."

And I hate to use the word conservative because I feel a lot of load data tends to deserve the label "candy ass" more than conservative.

I'm not saying the OP should continue shooting 90 gr of H1000... I'm saying he should back off to a charge that gets rid of heavy bolt lift, ejector swipes, smiley faces, and flattened primers while giving good accuracy... And if it's over Berger's listed max, then it's up to him to decide if it's still safe.

In my opinion, if lawyers and insurance underwriters designed roller coasters they would all be on a straight, level track 10 feet long and powered by a gondolier with a push pole.

Note: John I wasn't trying to pick on you or your post specifically. My point was that manufacturers don't just answer to their customers... The lawyers and insurance guys are always there wagging their fingers and saying, "Just to be on the safe side..."

Mike

I asked for some load data from Berger a while back and was told the data was from Quickload. I don't have have the Berger manual but it might state how the load was developed. Could the maximum be a Quickload calc that was then tested to see if it exhibited overpressure signs? Hornady says they pressure test then shoot real rifles for velocity. Hodgdon posts pressure (one to the few). In some cases they only shoot in real rifles and look for pressure signs. Most manuals do not give a maximum pressure but instead give a maximum safe load. That load may or not be a maximum pressure load. In Hornady's method of presenting data the load shown as maximum can easily be be 99 FPS lower than the maximum since their data is given in 100fps increments. In a 308 that's about 1.5 grains and in 223 its about 0.8 grains. Several bullet manufactures list the same charges for multiple bullets. Do they have the same maximum loading at rated pressure? I doubt it. In Nosler's 6th Edition they state they tested the loads in actual rifles and handguns in good condition. I suspect that they tested until they saw a traditional pressure sign and backed off. Do they have the same maximum loading at rated pressure? I doubt it. The data represents a safe load that is the maximum represented.

It's also important to understand that the rifle is the strongest part of the firing system. US manufactured rifles are proofed at around 1.335x the SAMMI service pressure. In the case of a 300 WM that's a minimum of 85,500 PSI. Primers and brass will fail well below that pressure. That is why we use those items to detect high pressure. I have seen estimates that hard bolt lift typically occurs around 70,000psi.

My point is that the maximum load shown in any manual is a maximum load determined by that manufacturer to be safe. It is not necessarily the load at maximum rated(SAAMI) pressure for the cartridge.

Lawyers and high level management would not set the data. They would and should require that the data be supportable. A lawyer would have issues explaining his data in court if a mistake were made. It's far outside his area of expertise.

 

[rmfield]

I had the same experience when I asked Berger for some load data on a cartridge not included in their printed manual. What I got was ultra-conservative Quick-Load data. It was pretty much useless except to establish a very safe starting point.

Regarding the OP's .338 loads, they definitely look too hot to me and the heavy bolt lift he describes just confirms that. I would suggest backing off at least 5 grains or what ever it takes to get rid of the pressure signs. Expect loose primers if those cases are reloaded.

 

[Doom]

I had the same experience when I asked Berger for some load data on a cartridge not included in their printed manual. What I got was ultra-conservative Quick-Load data. It was pretty much useless except to establish a very safe starting point.

Regarding the OP's .338 loads, they definitely look too hot to me and the heavy bolt lift he describes just confirms that. I would suggest backing off at least 5 grains or what ever it takes to get rid of the pressure signs. Expect loose primers if those cases are reloaded.

They sent me a page out of the manual with that statement.

 

[Supersubes]

Looks hot to me. Many ejector swipes. On a case that size, reducing a full grain of H1000 is only gonna shave about 30 fps, so backing off a few tenths will do nothing. Id back down to 87-88gr or so.

 

[OkieMike]

I asked for some load data from Berger a while back and was told the data was from Quickload. I don't have have the Berger manual but it might state how the load was developed. Could the maximum be a Quickload calc that was then tested to see if it exhibited overpressure signs? Hornady says they pressure test then shoot real rifles for velocity. Hodgdon posts pressure (one to the few). In some cases they only shoot in real rifles and look for pressure signs. Most manuals do not give a maximum pressure but instead give a maximum safe load. That load may or not be a maximum pressure load. In Hornady's method of presenting data the load shown as maximum can easily be be 99 FPS lower than the maximum since their data is given in 100fps increments. In a 308 that's about 1.5 grains and in 223 its about 0.8 grains. Several bullet manufactures list the same charges for multiple bullets. Do they have the same maximum loading at rated pressure? I doubt it. In Nosler's 6th Edition they state they tested the loads in actual rifles and handguns in good condition. I suspect that they tested until they saw a traditional pressure sign and backed off. Do they have the same maximum loading at rated pressure? I doubt it. The data represents a safe load that is the maximum represented.

It's also important to understand that the rifle is the strongest part of the firing system. US manufactured rifles are proofed at around 1.335x the SAMMI service pressure. In the case of a 300 WM that's a minimum of 85,500 PSI. Primers and brass will fail well below that pressure. That is why we use those items to detect high pressure. I have seen estimates that hard bolt lift typically occurs around 70,000psi.

My point is that the maximum load shown in any manual is a maximum load determined by that manufacturer to be safe. It is not necessarily the load at maximum rated(SAAMI) pressure for the cartridge.

Lawyers and high level management would not set the data. They would and should require that the data be supportable. A lawyer would have issues explaining his data in court if a mistake were made. It's far outside his area of expertise.

Touche sir, you have a point.

When I review load data I tend to forget they are listing stuff loaded to SAAMI spec... I can't imagine cramming a 225 ELD Match bullet into my .300 Win Mag brass at 3.340" I'm nearly 1/4" over that now. 1/4" is almost a mile where capacity/pressure are concerned.

And of course brass is another aspect that tends to get glossed over. Hodgdon data seems to be derived from Winchester brass almost exclusively.

So perhaps I was being a bit unfair to manufacturers in my previous post. However, when I compare Berger data to... say Nosler data for instance, you'll see some decent differences in listed max charges and recorded velocities. Yes, different brass and bullet profiles for each... But Berger does seem to tend towards the lighter side.

Mike

 

[Yondering]

I asked for some load data from Berger a while back and was told the data was from Quickload. I don't have have the Berger manual but it might state how the load was developed. Could the maximum be a Quickload calc that was then tested to see if it exhibited overpressure signs? Hornady says they pressure test then shoot real rifles for velocity. Hodgdon posts pressure (one to the few). In some cases they only shoot in real rifles and look for pressure signs. Most manuals do not give a maximum pressure but instead give a maximum safe load. That load may or not be a maximum pressure load. In Hornady's method of presenting data the load shown as maximum can easily be be 99 FPS lower than the maximum since their data is given in 100fps increments. In a 308 that's about 1.5 grains and in 223 its about 0.8 grains. Several bullet manufactures list the same charges for multiple bullets. Do they have the same maximum loading at rated pressure? I doubt it. In Nosler's 6th Edition they state they tested the loads in actual rifles and handguns in good condition. I suspect that they tested until they saw a traditional pressure sign and backed off. Do they have the same maximum loading at rated pressure? I doubt it. The data represents a safe load that is the maximum represented.

It's also important to understand that the rifle is the strongest part of the firing system. US manufactured rifles are proofed at around 1.335x the SAMMI service pressure. In the case of a 300 WM that's a minimum of 85,500 PSI. Primers and brass will fail well below that pressure. That is why we use those items to detect high pressure. I have seen estimates that hard bolt lift typically occurs around 70,000psi.

My point is that the maximum load shown in any manual is a maximum load determined by that manufacturer to be safe. It is not necessarily the load at maximum rated(SAAMI) pressure for the cartridge.

Lawyers and high level management would not set the data. They would and should require that the data be supportable. A lawyer would have issues explaining his data in court if a mistake were made. It's far outside his area of expertise.

I'm not defending Nosler, but they do have actual pressure testing equipment. They'll show it to you if you take a tour of their facility.

When I saw it, one of the setups was one of their actions mounted to a pressure barrel IIRC. So I'm not sure how much that represents "actual rifles", since those usually have tighter chambers/throats to make sure data is safe in most production rifles. IMO the difference between pressure barrel chambers and production rifle chambers is most of the reason for load data being conservative. And to be fair, that's the way it should be; a lot of reloaders don't take the time to learn this stuff well enough to be safe otherwise. But since we know that difference, and know how to work up safe loads - I'm with you on this, and have no problem going over published loads when circumstances indicate it.

For example, I've got a cheap RAR in 243 Win that won't get within 200-300 fps of published velocities with any powder, without going several grains over max. From what I can tell, it's got a very generous chamber and throat, and I suspect a slightly looser bore as well. Probably going to rebarrel it, but it's an example of my comments above.

 

[Doom]

When I saw it, one of the setups was one of their actions mounted to a pressure barrel IIRC. So I'm not sure how much that represents "actual rifles", since those usually have tighter chambers/throats to make sure data is safe in most production rifles. IMO the difference between pressure barrel chambers and production rifle chambers is most of the reason for load data being conservative. And to be fair, that's the way it should be; a lot of reloaders don't take the time to learn this stuff well enough to be safe otherwise. But since we know that difference, and know how to work up safe loads - I'm with you on this, and have no problem going over published loads when circumstances indicate it.

I would expect that they are using a universal receiver and using a SAMMI test barrel. That chamber would be specified by SAAMI for each cartridge. It is tight and is basically the smallest chamber that would be encountered in a commercial application. Some manufacturers (Like Remington) actually make their chambers larger, usually in the free bore. My 308 has a loooong free bore so velocity and pressure run low.

 

[lariat]

Did you do a ladder test? Is there a lower grain load that gives good/better results?

 

[Doom]

Touche sir, you have a point.

When I review load data I tend to forget they are listing stuff loaded to SAAMI spec... I can't imagine cramming a 225 ELD Match bullet into my .300 Win Mag brass at 3.340" I'm nearly 1/4" over that now. 1/4" is almost a mile where capacity/pressure are concerned.

And of course brass is another aspect that tends to get glossed over. Hodgdon data seems to be derived from Winchester brass almost exclusively.

So perhaps I was being a bit unfair to manufacturers in my previous post. However, when I compare Berger data to... say Nosler data for instance, you'll see some decent differences in listed max charges and recorded velocities. Yes, different brass and bullet profiles for each... But Berger does seem to tend towards the lighter side.

Mike

I think Hodgdon data was 92 gr compressed when I checked it at something between 2500 and 2600fps!

 

[cas6969]

Really flat and starting to cup. I'd say so.

Most people's "pressure signs" are in fact red flag danger danger run away signs, but with their trained eyeball, they know better than people in a lab setting with pressure testing equipment.

I've read people say things like "no real pressure signs like blown primers". That's like, "no early indications of heart trouble, like major near fatal heart attacks. "

 

[Pharmseller]

I don’t consider primer appearance as indicative of overpressure.

Velocity, bolt lift, and ejector marks are my keys.

Looks like you’re a tad aggressive on all three. Not too badly, but you might want to back off a bit, especially with regards to bolt lift.




P

 

[harry_x1]

Did you do a ladder test? Is there a lower grain load that gives good/better results?

Yeah, I can easily back off to 88 or 89.5 while retaining the node....I was not expecting such great input this question. Was super helpful. Will report back with new pictures (88 as well as 89.5) to get more feedback...thanks

 

[Yondering]

I would expect that they are using a universal receiver and using a SAMMI test barrel. That chamber would be specified by SAAMI for each cartridge. It is tight and is basically the smallest chamber that would be encountered in a commercial application. Some manufacturers (Like Remington) actually make their chambers larger, usually in the free bore. My 308 has a loooong free bore so velocity and pressure run low.

In my experience pretty much all major commercial rifle makers do that - making their chambers more generous, with longer and wider throats. Of course there are exceptions, but it's common enough to be broadly applicable.

 

[Haney]

Im going to say first that I agree with you.

But I'm also going to say that I have found Berger load data to be extremely "conservative."

And I hate to use the word conservative because I feel a lot of load data tends to deserve the label "candy ass" more than conservative.

I'm not saying the OP should continue shooting 90 gr of H1000... I'm saying he should back off to a charge that gets rid of heavy bolt lift, ejector swipes, smiley faces, and flattened primers while giving good accuracy... And if it's over Berger's listed max, then it's up to him to decide if it's still safe.

In my opinion, if lawyers and insurance underwriters designed roller coasters they would all be on a straight, level track 10 feet long and powered by a gondolier with a push pole.

Note: John I wasn't trying to pick on you or your post specifically. My point was that manufacturers don't just answer to their customers... The lawyers and insurance guys are always there wagging their fingers and saying, "Just to be on the safe side..."

Mike

I don't mean to make sense , but a Starting load is conservative for a reason . Unless you have test equipment like the big boys you don't know shit about actual pressure in a given rifle . Fact

 

[brianf]

not calling people out but its obvious that some people on this thread should not be giving advice on "brass reading"

additionally if you think its hot...its already over sammi...guaranteed

 

[Pharmseller]

not calling people out but its obvious that some people on this thread should not be giving advice on "brass reading"

Instead of peeing in the pool then walking off, why don’t you offer your own interpretation on the brass appearance?

That way we can all learn something.




P

 

[OkieMike]

I don't mean to make sense , but a Starting load is conservative for a reason . Unless you have test equipment like the big boys you don't know shit about actual pressure in a given rifle . Fact

Yes, a starting load is conservative for a reason. However book MAX shows 85 gr... OP was running 90 and still has a face, although he's showing serious signs of pressure.

Would you consider it foolish to back off to 85 and if there are no signs at 85, slowly working back up? Or are you going to pound your fist on the table and yell "Damn it, 85 is book max and no one should EVER go beyond it!"

Mike

 

[brianf]

Instead of peeing in the pool then walking off, why don’t you offer your own interpretation on the brass appearance?

That way we can all learn something.




P

Obvious pressure signs

Some partially cratered
Some ejector marks
Some swipe marks

I have also done piezo pressure testing in a previous life, so I can say with certainty more often than not handloaders are above sammi.

Now it could be bolt face flex, wet chamber, wax on brass, chamber too smooth, particular lot of brass, powder open to the environment, powder at the bottom of the bottle that has more fines/mesh size …the list goes on.

Brass isn’t the be all end all of “signs”. It’s just the simple one

 

[brianf]

Yes, a starting load is conservative for a reason. However book MAX shows 85 gr... OP was running 90 and still has a face, although he's showing serious signs of pressure.

Would you consider it foolish to back off to 85 and if there are no signs at 85, slowly working back up? Or are you going to pound your fist on the table and yell "Damn it, 85 is book max and no one should EVER go beyond it!"

Mike

problem with going above max in general

pressure curves are not linear, it gets to a point and spikes

is the shooter testing with equipment

although he "still has a face" is he aware of the max pressure the action can handle, has the mfg published destruction testing

does the shooter know if the lugs are getting set back causing other issues

the list of possible negatives far outweighs the possible positives

 

[338dude]

Just looking at the case heads it doesn't look like there is anything in the extreme range. I don't see any ejector marks or swipes from the case stuck in the chamber when the bolt is rotated. How did things feel when you went to chamber the next round? Did the bolt lift seem difficult? I'd ask about the recoil but not knowing what brake/barrel combination or your level of feel for recoil energy that would be pointless.

I see more flat edged primers than round edged primers I would say you are there,if you go any direction it should be down.

 

[lariat]

I'm still in the camp of finding a lower accuracy node that isn't above or near max load and being cool with that accuracy and lower fps. Change the bullet to something with a smaller bearing surface on the rifling, etc. Nobody wants to immediately regret a decision one day or have a buddy shoot the rifle and live with his injury on one's conscience. Drop the testosterone from 11 on this and be safe.

 

[Pharmseller]

Obvious pressure signs

Some partially cratered
Some ejector marks
Some swipe marks

I have also done piezo pressure testing in a previous life, so I can say with certainty more often than not handloaders are above sammi.

Now it could be bolt face flex, wet chamber, wax on brass, chamber too smooth, particular lot of brass, powder open to the environment, powder at the bottom of the bottle that has more fines/mesh size …the list goes on.

Brass isn’t the be all end all of “signs”. It’s just the simple one

I’m not as experienced as most, but how reliable is primer appearance? Don’t primers have varying degrees of hardness? As a result, don’t some show high pressure where high pressure might not exist? In addition, doesn’t primer seating variances cause different degrees of appearance?

 

[Frank Green]

Just looking at the pics.... and then the OP saying it had heavy bolt lift. Your over pressure.

Also to everyone reading this......just because you don't have pressure signs at all.....on the brass or on bolt lift doesn't mean you are not over the max working pressure for a given cartridge.

I won't say what caliber but I took some of my ammo before real data was released for a new cartridge....and being as we where making the test barrels for the new cartridge...I asked the ammo maker if I could send them some of my ammo for testing in regards to pressure. I gave them 10 loads of each. Same bullet, same lot of powder, they're cases (from the same lot) and the primers I used and the lot number as well. At one grain of powder over of what they considered a max load my pressure jumped 5k or 6k psi over the max saami listed for the cartridge. There where no pressure signs at all. No flat primers, no ejector swipes no hard bolt lift etc...so just because you don't see it or feel it....or can measure the brass etc...doesn't mean your not over max working pressure.

At 90gr of powder I'd say your about 5 grains of powder give or take a couple of grains over a max load. I ran a similar load doing some testing for Remington back in March of 2009 prior to the original PSR solicitation. I had heavy bolt lift and ejector marks and swipes on the brass. Frickin load accuracy wise just pounded stupid small groups though. Go figure as usually that doesn't happen!

What the OP doesn't say and no one has touched on as well.....what chamber spec reamer was used to cut the chamber? This can have an effect on pressures as well.

Also you don't know as to what spec. the barrel was made to on the bore and groove size. Factory AI rifle built here in the States. Most of the barrels are ours but that doesn't mean the OP has not replaced/rebuilt the gun with a different barrel and or the barrel is not ours. Unless requested by the customer we run saami min spec. on the bore and groove sizes and tolerances. If your barrel is tight on bore and or groove size or if both dimensions are tight....you will easily drive up pressures and velocities and give you false readings on your brass and or bolt lift. Even if it is our barrel we don't chamber the barrels for AI. I don't know what spec. AI uses for the chambers and or if the barrel was replaced...again what reamer was used to cut the chamber can make a difference.

Also to the OP....you said the first 5 rounds fired you had no hard bolt lift but then bolt lift started getting hard? If so and you started with a clean barrel....that's also a sign as you start laying down the carbon fouling / build up that will also influence pressures as well and it's telling you that you are too hot on the load.

Either way my vote is your loads are too hot. Back them off.

Go for the accuracy first. So what if the load is a 100fps slower than what you want or think you should get. Put an extra click or two on the scope and don't worry about it too much. Accuracy first and reliability and safety regardless of temperature you are shooting the gun is what I look for. I like fast also and can be a velocity freak at times myself but I also deal in reality.

Later, Frank
Bartlein Barrels

 

[Haney]

Yes, a starting load is conservative for a reason. However book MAX shows 85 gr... OP was running 90 and still has a face, although he's showing serious signs of pressure.

Would you consider it foolish to back off to 85 and if there are no signs at 85, slowly working back up? Or are you going to pound your fist on the table and yell "Damn it, 85 is book max and no one should EVER go beyond it!"

Mike

Take a look at what Frank just posted . Maybe you will learn something . Experience is the best teacher .

 

[OkieMike]

Take a look at what Frank just posted . Maybe you will learn something . Experience is the best teacher .

Gee, thanks dad. Does that include blazing up at the range too?

Mike

 

[ma smith]

Gee, thanks dad. Does that include blazing up at the range too?

Mike

Don't have a dog in this fight, butI'll quote part of Frank's advice which should clue us all in to pay attention...

with emphasis added on the 'real world' experience bit...

At 90gr of powder I'd say your about 5 grains of powder give or take a couple of grains over a max load. I ran a similar load doing some testing for Remington back in March of 2009 prior to the original PSR solicitation. I had heavy bolt lift and ejector marks and swipes on the brass. Frickin load accuracy wise just pounded stupid small groups though. Go figure as usually that doesn't happen!

 

[OkieMike]

Don't have a dog in this fight, butI'll quote part of Frank's advice which should clue us all in to pay attention...

with emphasis added on the 'real world' experience bit...

That's fine. But here's the big question...

It was stated earlier in the thread that it's likely that most handloaders are over pressure... And that the telltale "signs of pressure" aren't really reliable... But they're all we have. (Unless you have a piezoelectric strain gauge laying around)

So if you are at the upper end of book limits and have no telltale signs of pressure... How do you know you aren't already over pressure?

Simple. You don't.

So your choices are A) Trust the time honored signs indicating overpressure conditions... Or B) Load at book minimum... Or C) Hang it up and buy factory ammo only.

Or D) buy a PE strain gauge.

Mike

 

[Frank Green]

That's fine. But here's the big question...

It was stated earlier in the thread that it's likely that most handloaders are over pressure... And that the telltale "signs of pressure" aren't really reliable... But they're all we have. (Unless you have a piezoelectric strain gauge laying around)

So if you are at the upper end of book limits and have no telltale signs of pressure... How do you know you aren't already over pressure?

Simple. You don't.

So your choices are A) Trust the time honored signs indicating overpressure conditions... Or B) Load at book minimum... Or C) Hang it up and buy factory ammo only.

Or D) buy a PE strain gauge.

Mike

Mike, You hit it on the head! Or most of it!?

All I can tell you is trust the loading books. I don't trust loading books from 30 or 40 years ago. I've got plenty of examples of why not to.

Also for the simple reason when you change the lot of powder or brass or primers or bullets etc...that's why they say to back off your load you where running and recheck everything. Even changing the reamer spec. will have an effect.

Do I always do that? Back off the load when I make a component change like a different lot of primers....No. Just being honest there!

I trust the Hornady data, most of the Federal cartridge stuff, and Sierra data. Why? I know we make nearly all of they're ammunition test barrels. If there is a problem going on...I'll know about it way before anyone else. We are just getting back to making barrels for the old Remington ammo plant again along with another place. We also make test barrels for other places as well but don't know if they use us exclusively. We do stuff for Barnes and even Weatherby now etc…

I don't push it past the max recommended loads. Go back to my example where 1 grain of powder over the max listed load I gave...and pressure went up like 5k or 6kpsi.

A good example is on my 6.5CM. Both of my comp guns that I would use to sling 150gr/153gr bullets thru. I'm at the max book load and maybe a .1 or .2 over. Depends on which book you look at. I have no pressure signs at all anywhere along with normal bolt lift. 150gr bullets at an honest 2700fps give or take a couple of fps. but I in no way will even think about adding another couple of grains of powder to the case.

A strain gauge on the side of the barrel isn't a good way to check for pressure. It's an indicator but not a real accurate one.

 

[Yondering]

A good example is on my 6.5CM. Both of my comp guns that I would use to sling 150gr/153gr bullets thru. I'm at the max book load and maybe a .1 or .2 over. Depends on which book you look at. I have no pressure signs at all anywhere along with normal bolt lift. 150gr bullets at an honest 2700fps give or take a couple of fps. but I in no way will even think about adding another couple of grains of powder to the case.

A strain gauge on the side of the barrel isn't a good way to check for pressure. It's an indicator but not a real accurate one.

In the case of that CM load, I fully agree, but I'm betting you know from reference to published data that your velocity is right up at the top end of where it should be as well. And IMHO, that's a pretty important piece of data.

Now take the exact same load in a different barrel, one where you know the throat is longer for example - and say the velocity is only 2550 fps. Say it's the same barrel length, to make it easy. In that case, IMO it's a pretty safe bet pressure is lower in this second barrel, and within reason it can be safe to increase the load a little to approach that 2700 fps number again. That doesn't mean a good loading practice is "more powder until you hit book velocity"; I'm not saying that at all. But velocity is an important indicator, and IMO a far more reliable indication of relative pressure with identical components than primer appearance or some other things mentioned in this thread. That's not my own made-up idea either, it's come from several ballisticians who've worked for some of the ammunition manufacturers.


The problem with a strain gauge reading is that you don't have a baseline for reference. (OK, a second problem is frequency of the data aquisition and missing spikes, but that's a separate, and much more nerdy, discussion.) You or I can measure a strain value on our rifles, but we don't have any way to accurately correlate that value to pressure. Since chamber dimensions, temperature, fouling, and all sorts of other things affect pressure, you can't just fire a factory load and say that measurement is max pressure - it most likely may be well under pressure, or in some few cases it might even be over. I've been working hands-on with strain gauge data recording for over 20 years, but this one fact is why I've never bothered with it on my rifles. The value is just very limited.