I've been reading an article by Nick Harvey called 'Work Up To Maximum Loads Safely' (Sporting Shooter March 2021) in which he deals with the matter of measuring head expansion.

First he says that expansion of the solid head of as much as.001" is a warning signal of excess pressure, and I agree. However, he then says that the charge should be reduced by 6 per cent. It seems to me that in many cases that would take the load back to below manuals' starting levels.

I would have thought that we should drop back to at least where there is no measurable expansion but that to go back 6 per cent suggests any conservative reloader who never gets to observable expansion is not safe, just not risking his safety to find out what is safe.

Even stranger, he then says Hornady engineers "found case head expansion for low-pressure cartridges like the.30-30 should be .003 to .004 inch maximum, while mid-pressure range cases like the .22-250 or .30-06 should be .005 to .006 maximum ...".

Much as I appreciate his going into these matters, I think there is also a problem with that last statement and suspect the Hornady engineers were in fact measuring the webs ahead of the solid heads; I had always understood that measuring solid heads did not apply to "low-pressure cartridges" because by the time any expansion could be detected there, you'd be so far into dangerous territory that serious damage to the brass and rifle might already be occurring, esp. in doubles and lever-actions.

What does the membership here think about this subject?

All complete nonsense. Sure, back in the day, it was de rigeur to measure the solid head for expansion. I never subscribed to the method, and always considered it to be non representative of anything. Because as we know, all brass is not the same, even from the same maker in different years of production, so how can we use the case to determine pressure? Even the hard extraction sign can vary. But at least we know, for that brass, we are at a max for it. Even if not for the rifle.
As for measuring the brass ahead of the solid head, that is super bogus and tells you Nothing.
I go by the factors we all discuss here; primers, case extraction. that's it.

I tried taking case head expansion measurements for a time but gave up due to doubt of its usefulness. For reliability I think ( IIRC ) measurement is to be made on the same case at the same position on the circumference every time ( very difficult ). When doing this religiously, with the same lot of brass, readings were far from consistent, varying from no apparent expansion to more than recommended. I couldn't interpret what it meant. And it all took so much time it became pointless. I did this with only the one calibre, .270 W and Norma brass, although originally intended to include all calibres I shoot.
Among the few guys with whom I discuss handloading these days it's just not a topic that comes up. I don't know anyone who relies on this method. My handloading approach is to work up in careful steps, checking on case extraction and primer condition with each shot, aiming for the ideal load at NEAR maximum, not absolute maximum. Usually I find this with an appropriate powder and nearly full case ( my preferred scenario ). With medium to slow powders I find pressure warning signs ( sticky extraction, very flat primers ) usually come on gradually and I've never run into dangerous territory with my approach. Fast powders, which I rarely use, are a different proposition going from safe to overpressure with the slightest powder weight increase. Overpressure loads with these have given me both sticky extraction and the odd blown primer, at least showing excess pressure with certainty !
Beyond settling on what I consider any safe load I have ongoing awareness of brass condition ( e.g. split necks, loose primer pockets ) as pressure indicators. Any early onset of these indicates pressures may still be a little high and need tweaking back slightly into safer territory.

the key is to use factory ammo as a baseline.
then taking apart some of the rounds in that box and using the virgin cases to compare your loads to theirs.

the point of that is to have an apples to apples comparison of known tested safe pressures.

that's all you get from the exercise.

I never use factory ammo.
And, I submit, it still tells you nothing of value because are using different make or year of brass.
It will always be apples to tomatoes no matter what you do. Maybe breaking down a factory round and using the exact same brass, might be valid.

Thanks guys,
What do you do when you do perceive excess pressure: back off 6% as Nick Harvey advised or just go back a grain or two?

quote:

sambarman338
posted 02 January 2023 20:27
Thanks guys,
What do you do when you do perceive excess pressure: back off 6% as Nick Harvey advised or just go back a grain or two?

Yes, with the medium & slow powders I tend to use I drop back to the charge under the one showing ( suspect ) excess pressure. That's usually about 0.8 - 1.5 gns. Then I target shoot that load again to ensure the accuracy remains acceptable.

There many indications of high pressure.

One only knows them by experience.

I don't know of many; just two. Sticky extraction is #1; really flat primers might be another, leaking primers is definitely one. Or it might be the make of primer.
Remember, our rifles can take FAR more pressure than the primer/case interface can. That is the weak link. And that is how SIG is making the new Army 6.8 and 338s; steel case heads. Operates at 80K psi. And that is how our M256 tank cannon works at ump to 100K PSI; steel case and screwed in electric primers.
There is no formula for backing off; since I work UP to the load, when one gives signs of high pressure, I then go BACK to the load that didn't. Not automatically one, 6, or anything.

quote:

Originally posted by dpcd:
I don't know of many; just two. Sticky extraction is #1; really flat primers might be another, leaking primers is definitely one. Or it might be the make of primer.
Remember, our rifles can take FAR more pressure than the primer/case interface can. That is the weak link. And that is how SIG is making the new Army 6.8 and 338s; steel case heads. Operates at 80K psi. And that is how our M256 tank cannon works at ump to 100K PSI; steel case and screwed in electric primers.
There is no formula for backing off; since I work UP to the load, when one gives signs of high pressure, I then go BACK to the load that didn't. Not automatically one, 6, or anything.

Agree . . . would you include an extractor mark on the case head?

Ejector hole on Remingtons, ejector slot on CRF ones. Extractor cut like on a Sako. CRF bolts aren't cut for extractors.

I remember that this was all Ken Water’s method. Meticulous measurement of case head expansion. I always remember his loads being lower than most all book loads.

The availability of hobbyist strain gauges has shown how off CHE is. It’s very subjective and not at all accurate.

If you use rather minimal criteria, you certainly won’t get in trouble, but it doesn’t tell you much about real maximums.

quote:

Originally posted by crbutler:
I remember that this was all Ken Water’s method. Meticulous measurement of case head expansion. I always remember his loads being lower than most all book loads.

The availability of hobbyist strain gauges has shown how off CHE is. It’s very subjective and not at all accurate.

If you use rather minimal criteria, you certainly won’t get in trouble, but it doesn’t tell you much about real maximums.

I was staying at Steve Vogel's house, he was married to Bill Ruger's daughter and in charge of Ruger.

He was a close friend of Ken Waters, and took me to Ken's house.

We talked about all sorts of things related to shooting and reloading.

Ken was extremely knowledgeable about this subject, and I learned a lot from him.

We stayed in touch until his passing.

Excessive pressure indications in every rifle is subject to THAT rifle alone.

I get all sorts of rifles here, many of them from very small custom makers in Europe.

Practically all of them are made to much closer tolerances.

Some will take loads that are over book maximum.

Others might not handle loads that are minimum in some books.

This is normal.

I have had BRNO rifles in 243 Winchester that will blow factory ammo primers completely.

The primers pockets were so expanded the primers fall out.

The same factory ammo shoots just normally in other rifles.

I don't even flirt with pressure.... much.

all I look for is accuracy and enough speed to get the job done.

my 30-06 runs a 150 at 2800.

the wifes runs a 150 but only to 2650 ish.
she ain't gonna shoot a deer at 300 yds., and she is comfortable with the rifle.

I run my 25-06 at 3-K with a 100gr. bullet.
the other one is 3-K with a 120.
my 257-R is 2750. with a 120.
my ICL is 2875 with a 139
the standard 7X57 [the youngest girl shoots] is 2750 with the same bullet.
my other 257R shoots an 86gr. bullet at... 2400 fps.
my 358 win is 2350 with a 250gr. bullet.

they all have room for more, some a lot more.
but they like it where they are, and they all do the job they are asked to do.

I get no surprises, no ejection or chambering problems, and I know what the bullet is gonna do when it gets there.

I've never ever once had an animal walk over to me and give me a bullet back, then walk off laughing
nobody has ever looked at one of my targets and said man you need more practice either.

Thanks everone,
Compared with you, I am indeed an amateur, one who has perhaps had the misfortune to have repeatedly bought rifles with tight dimensions, whereby I've never got to any book maximum.

In bolt-action calibres I find some primer flattening universal though I've only ever seen cratering a few times, and always with factory ammo.

Because I want my barrels to last as long as possible, I space out my shots at the range when I can by checking head expansion, primers and velocities, as well as where that bullet went on the target, before I shoot again.

Unlike Nick Harvey, I don't put my (conventional) micrometer in front of the 338 magnum's belt, because the web(?) in front of that gets in the way as it expands to fill the chamber. So, I measure the belt or solid head just in front of the extraction cannelure, expansion of which might relate to enlarged primer pockets.

Though this is inexact, I have occasionally seen the solid heads expand by .001" over what they were before firing, beyond the initial expansion from virgin brass. At that point I'm inclined to dpcd's outlook - back off to a load where no visible expansion occurs.

I've never had any primers fall out but try to check for that likelihood in some calibres by tapping out the old ones with a pin and hammer rather than using the resizing-die pin. If ever primers come out with fewer than five or six taps, I'll start to wonder.

I like looking at chronograph results, too, thinking that if velocities exceed what the manuals give as max, something may be amiss.

I've only encountered difficulty in opening a bolt with one rifle, my old 1927 Breda Greek MS. There, my reloads have been so conservative that I suspect setback, so may retire it to the cupboard.

Feel free to criticise these thoughts - I'd rather be labelled as blind to the truth than be blinded by a blow up.

Just to address something in your first post: I'm guessing the article wasn't suggesting measuring in front of solid web and getting .003 to .004 expansion for mild cartridges and .006 to .007 CHE for hot cartridges. I'm betting he mis placed the decimal point and was talking about measuring at base.

part of the problem with the che measuring is that you got brass and a chamber.
the brass is gonna swell up to fit whatever hole it's in.
re-size it and it swells back up again.
how much did you size it down?
you could get 10-12 thou of swell with 30-K if your just blindly sizing and measuring.

Well, skl1, Nick did add the Hornady maximum figures for high-intensity cartridges (.006 to .007"), too, which makes me think the figures were as intended. That they were miles away from his initial claim that .001" was excessive still bothers me, though. Nick must be at least 90 now and that magazine's proof reading is often dodgy, but he has published an accepted reloading manual in the past.

I think I see what you're suggesting, though, that those figures should have been 10,000ths, eg .0006 to .0007".

Yes, Lamar, brass will expand to fill chambers but I think that expansion is reduced once we get back into the solid head.

I rarely set my dies to full-length resize completely but initial measurements from which I judge expansion are those found just before firing, then compared with the ones afterwards. I usually measure the diameter across from the first letter of the brand name but take others as well in case of great divergence.

Huge misconception; Measuring forward of the solid head tells you NOTHING: forget that idea.
And for me, measuring the solid head, tells me nothing of value.

the relevant units at 0.000X not 0.00Y ..

while you CAN measure a case, fire it, and measure it again, those measurements are ONLY, repeat ONLY relevant to that singular case.. you can't take an average and work from there. and ONLY relevant to that specific chamber it was fired in ... and a sloppy oversized chamber COULD return "Scarey" results

unfired brass expanded more (or less) on first firing.

I tried this on my reloading journey - found no value in it, really, as a 0.0005 expansion might still show rounded edges on primers, or a leaky primer ..

Yes, dpcd, I agree, esp in regard to front-locking bolt actions. I have been known to compare expansion at the web on .45-70 cases, however, because waiting to find it on the solid head could be disastrous and the primers are supposed to say nothing at all. That web checking may also be meaningless but did make me wonder about a particular bullet: all other loads enlarged the cases by about three thou there but with this one they soon grew to 0.007" yet the primers were still perfectly bevelled.

Thanks jeffeosso, I guess your observation about the individuality of cases is correct,too, but if each of the cases from my three-shot groups at one load level show a similar expanding tendency, I'm inclined to take notice.

I have read somewhere that some expansion in a factory load is to be expected and that it is any expansion after that that we need to watch out for. I don't reload cases from my son's .30-06 on the rare occasion he uses it, though, because I know it has 12-thou headspace and probably ruins every one.

Maybe 0.0005" at the solid head is or isn't enough to worry about. I had previously thought 0.001" indicated excess pressure. If you think 0.0005" is too much, then perhaps some primers don't flatten soon enough. I see now that Joyce Hornady certainly considered that 0.0005" was too much, so I had better pull my head in - at the range if not the reloading bench.

Ive seen a lot of reloaders say that checking primers is unreliable. That has not been my experience. I go by published factory specs, chronograph velocity and primers. And more often than not they tend to correspond pretty well. Of course there will be some variation. But typically if a 30-06 shooting 180 grain pills is close to 3000 fs that is probably not within the ideal pressure range. Just an exaggeration to illustrate the point.
Primers are my primary pressure check though. And if you have hard bolt lift, then chances are good that you had flattened primers several grains of powder before ever getting to that point.
I dont have the patience or expertise to measure case heads. My above method has always served me pretty well.

I have spent a lifetime working up max loads in all my hunting rifles..One indication of pressure alone is normally insignificant. two indicators is to be acknowledged at least..

I look for pressure by the numbers, starting with a flat primer, but primer hardness is a varible. then a flat primer with a black ring and a smear, gets my attention, so may proceed at half gr. increments . until I get a ejector mark at which point I see head expansion as a rule, and time to back off a grain or two and a good time to test on the chronograph and brass condition such as primber snugness..Some times I push the string at this point and go a bit more, looking for a blast sound as opposed to a boom, sticky bolt, and ring around the base of the case. At various times I may stop at any point especially if I get two or more indications, and yes Im flying by the seat of my pants, and at 60 plus years I have only had minor set backs, and a couple of iffy times when I ran backwards, but never injured self or gun..and not always in the order as posted, stayed considerate of each indication..Even used heavy gloves and a welders Helmet a few times, I say a few times..

I measured case heads sometimes, and it is an indicator or sorts IMO, when combined with other indicators it seems to match up and be in order, I know that .005 is always max and .oo2 is usually a hot good max load ( I said usually) but I always combined that with other max load indicators..

and above all I remained flexible, and always have known "my guns max"..after testing, followed by long time use and reloading numbers, and cutting back a few times at this point..

[/QUOTE] Thanks guys,
What do you do when you do perceive excess pressure: back off 6% as Nick Harvey advised or just go back a grain or two?[QUOTE]

Sambarman, "In the beginning", the reloader was suppose to match factory loads. It was suggested the reloader measure before and again after, measure what? Measure the diameter of the case head. It was suggested the factory load expanded the case head .000250". If the reloader was able to match the factory load with powder and bullet the second firing with the identical load should increase the case head diameter by .000250. meaning the case head diameter should measure .00050", thinking ahead, after firing the case 4 times the case head diameter should measure .001250".

I have loaded once fired cases that expanded the case head .005" and I have loaded once fired cases that expanded the case head .010" and everything in between.

And then there are tools that are used to measure the diameter of the case head. The first micrometers I used were bladed micrometers. after that came the indicator micrometers, I can not afford new indicator micrometers, new micrometers start out in the $500.00 range. And then I made a few tools that would allow me to measure the effect the load had on the case head. I sent a few gages to an old friend, the last I read about his writings indicate he has can not find them. All of the tools were based on the idea if you did not measure before it is too late to measure afterwards.

F. Guffey

Thanks again, all advice evaluated and absorbed. If I ever feel the need of a welder's helmet, hopefully it will have clear 'glass' as well as dark

I never needed the helmet, just felt like it might be a good idea in a couple of cases, but it never was...I was dealing with lever guns in both cases and all litature was with bolt guns in those days. Today based on those early load workups I just work up to about book max and cut two grs. and call it good with the SAvage 99 and Win. 94s etc.

I have seen articles by other gun writers where they just loaded new brass to a mid-level in the manual - and guess for one shot that works well enough.

I have to tuck long/mono bullets so far into cases, though, that maybe even starting loads are sometimes too high.

I have used the method and it works, however it only works in the rifle your testing in with the brass you're using. Also, the limits of the brass don't tell you what the pressure was. Brass doesn't just grow in a linear fashion according to pressure. It goes up a little, like .0002, then levels off for close to 1/2 grain. Then goes up again before leveling off. The 3rd time it goes up, STOP. Nothing good will happen after this point.

Keep in mind the rifles in question. My BAT actions won't even blink at loads that a Savage couldn't even dream of.

quote:

Keep in mind the rifles in question. My BAT actions won't even blink at loads that a Savage couldn't even dream of.

I call BS. Any modern turnbolt action will contain pressure FAR beyond that which will rupture the far weaker primer and brass case.

It may well be true that, due to the chamber variations, bore/groove diameter, interior barrel finish, etc., that one rifle will show significantly higher pressures than another in the same caliber, but it has nothing to do with the action itself, BAT, Savage, or otherwise. By the way, I'm no fan of Savage actions, but not because of any lack of "strength".

Never ever measured case heads for pressure sign, complete waste of time. While primers may give an indication of higher pressures without any other indications such sticky bolt lift or incipient case head separation, there is nothing wrong with this higher pressure.
Below is the case head of a fired factory 7x61 S&H round with very flattened primer. Fired in the rear locking Schultz and Larsen rifle which have been tested to over 120,000psi with no ill effect. If sized to headspace on the shoulder these Norma cases gave good case life.



The Hornady Superformance ammo for 7mm-08's shows good flattened primers and I reload with same Hornady case and 139gr SST bullet to same velocity and primer flattening with no sign of sticky bolt lift, ejector mark or premature degradation of cases and primer pockets.

Velocity and accuracy are what I load for, I don't get my knickers in a twist trying to measure case expansion or determine pressure.

The appearance of the primer may have nothing at all to do with the pressure of the load. If the chamber is slightly long relative to the brass case (a bit more headspace than necessary) then upon firing the primer will first back out until it meets the bolt face as the brass case grips the chamber walls and remains in its forward position. Next the case head will move rearward (stretching slightly at the pressure ring where the brass becomes thin enough to grip the chamber walls). When the case head moves rearward the primer is "reseated", so to speak. But the primer has flattened and spread slightly against the bolt face, thus giving the appearance of a primer flattened by pressure.

It is only when headspace is minimized (as with a once-fired and neck sized second loading) that an excessively flattened primer provides an indication of higher pressures.

Cratering around the firing pin strike can also be a sign of high pressure, but that depends on how snugly the firing pin fits in the firing pin hole in the bolt face. If a sloppy fit then "normal" pressures can show cratering on the primer.

Bottom line: Visible pressure indications may be dependent on the particular gun and ammunition. However, sticky bolt function is usually, though not always, an indication of pressures beyond the level of sustainability with that particular lot of brass.

quote:

Originally posted by 30.06king:
I tried taking case head expansion measurements for a time but gave up due to doubt of its usefulness. For reliability I think ( IIRC ) measurement is to be made on the same case at the same position on the circumference every time ( very difficult ). When doing this religiously, with the same lot of brass, readings were far from consistent, varying from no apparent expansion to more than recommended. I couldn't interpret what it meant. And it all took so much time it became pointless.

My experience mirrors this exactly.

I mic a case head on new brass, fire the round, then measure the case head..It measures depending on the rifle/chamber, but its consistent and seems to agree with other fly by the seat of our pants, nor does any one shot test, what we do is better than using a coffee cup of powder..flat primers vari but need to be a warning, primer material seems to vary in hardness btw. smokey rings is another warning, an exracter mark in the case head is time to back off, now after the above measuring a case head is not a bad idea..a crack sound as opposed to a boom is an indicater Im told and it seems to be btw..You are now pretty close to a stickey bolt and case head seperation...Like I said we fly by the seat of our pants, those newbies to reloading would do well to start at book beginning loads and work up using one case, a chronograph and watch for loose primers, and it works well enough and seems to keep you out of trouble and never go beyond 2 grs over book max!..Just my two bits.

quote:

Originally posted by Stonecreek:

quote:

Keep in mind the rifles in question. My BAT actions won't even blink at loads that a Savage couldn't even dream of.

I call BS. Any modern turnbolt action will contain pressure FAR beyond that which will rupture the far weaker primer and brass case.

It may well be true that, due to the chamber variations, bore/groove diameter, interior barrel finish, etc., that one rifle will show significantly higher pressures than another in the same caliber, but it has nothing to do with the action itself, BAT, Savage, or otherwise. By the way, I'm no fan of Savage actions, but not because of any lack of "strength".

I have 2 savages, and the loads that the BAT action runs with would have primer pockets blown out 4grs of powder earlier.

If that test is not with the SAME barrel, then your test, and assertion, is completely invalid.
It ain't the action that causes the pressure.
I've said this before but no one listens; modern bolt actions can withstand FAR more pressure than we can contain safely in a brass case. I use a case in point which I am quite familiar with; the M256 tank cannon. It is nothing but a big sharps dropping block action, but our ammo routinely operates at close to 100K PSI. And the bullet goes out at 4850 FPS. How? We use steel cartridge cases and a steel, electric, screwed in primer.
Look at the new SIG M5 Infantry rifle; steel heads and operates at like 80K psi.
If you don't understand that there are literally an infinite number of variables involved in hand loading for the rifles we are using, you need a new hobby. I recommend knitting. It's much safer.

quote:

Originally posted by dpcd:
If that test is not with the SAME barrel, then your test, and assertion, is completely invalid.
It ain't the action that causes the pressure.
I've said this before but no one listens; modern bolt actions can withstand FAR more pressure than we can contain safely in a brass case. I use a case in point which I am quite familiar with; the M256 tank cannon. It is nothing but a big sharps dropping block action, but our ammo routinely operates at close to 100K PSI. And the bullet goes out at 4850 FPS. How? We use steel cartridge cases and a steel, electric, screwed in primer.
Look at the new SIG M5 Infantry rifle; steel heads and operates at like 80K psi.
If you don't understand that there are literally an infinite number of variables involved in hand loading for the rifles we are using, you need a new hobby. I recommend knitting. It's much safer.

Thanks, dpcd.

I've tried to explain this over and over, but some people simply reject logic in preference of prejudice.

I have no idea whether a BAT action or a Savage action's integrity would be exceeded first nor at what pressure, but in either instance the brass case would have failed at a fraction of that pressure. Sainted gunsmith Parker Ackely did a series of blow up tests and felt that the Japanese Arisaka was the toughest he tested (but again, the internal pressures in his tests with different cartridges, powder, and brass would have been apples and oranges, so I'm not sure I'd have that much confidence in his assessment.)

Another way a chronograph can be useful in watching for excessive pressures is to watch for sudden velocity spikes. Say for instance you are working a ladder in .5 grain increments and the velocity gains average 35-40 fs per increment, then you suddenly see a 85-90 fs gain. The odds are real good that will have come with a flattened primer as well.

quote:

If sized to headspace on the shoulder these Norma cases gave good case life.

"Never ever measured case heads for pressure sign, complete waste of time".
If I had the luxury of disagreeing , I would disagree.

F. Guffey

If I see flattened primers, extractor marks on the case head. I back off a couple of grains. If I have sticky extraction I back way off and probably change to a different powder. That being said I have a pet load for my 270 Win, that gets 3000 fps out of a BDL with a 22" barrel with 150g Partitions. Not a light load but zero excessive pressure signs. I reload cases 10 times then throw them out. So I'm not extremely conservative but I am careful.

quote:

If sized to headspace on the shoulder these Norma cases gave good case life.

If sized to seat on the shoulder the case body ahead of the belt will not will not have case body support ahead of the belt.

F. Guffey