Was discussing this with a friend over the weekend. Has anyone scientifically documented that this has happened rather than just by deduction and "assume" that that is what happened when they see excess pressure signs with what should have been mild loads. It should be possible to see it on the pressure trace shold it not? Or is the whole SSE thing a myth?
Regards,
JohnT
No it happened last night after 10 Burritos and a half doz. bottles of Alaskan Amber!!!!
It's not a myth.
It happens.
I can produce it at will but don't since I'm not "into" blowing guns up.
There are more than one way to get the result, which I long ago resolved not to write about, because as sure as shootin', some nitwit would blow some fingers off just trying to prove me wrong. I frequently warn about these unwise loading practices, of course, but I don't present them as causes of the "SEE" or mention them in discussions of the "SEE."
The simplest way to put it is that you don't have to worry about the "SEE" if
(a) you don't try to wring the last possible foot/second of muzzle velocity out of your gun
and
(b) you always use ninety to a hundred percent of a case-filling charge of your optimum powder (which may not be your personal favorite and may not be listed in your manual).
Seems like Dr. Howell wrote an article about it in RifleShooter mag several years ago...I see if I can dig it up.
OK, April 1998...page 70. If you can find a copy it will cover a lot without him having to type it all again.
I seem to recall that most of the SEE blowups (and to the OP, no there wern't signs of excess pressure) were from working down "mouse fart" loads, not trying to gain a few extra FPS.
This "sample" is hanging on my gunsmiths wall, the load data presented is what he remembers (it's been more than a few years) loading it with. 9 rounds fired, 9 holes in the target, rifle blew on shot # 10.
![[Linked Image]](http://i81.photobucket.com/albums/j212/Tailgunner1954/Blown86Win2.jpg)
True about working up "mouse" loads. But P. T. Kekkonen wrote of S.E.E. occurring in a .243 WCF, 80 grain bullet, and a reduced charge of then new Norma MRP. He wrote that the pressure test setup blew up - "disintegrated" - and the test was repeated. The second testing setup blew up after a few shots (pressures slightly less than normal) with the piezo gauge peaking out at its maximum, about 150,000 PSI, before breaking. He opined that the actual peak pressure could have exceeded ten times that.
THE POWDER CHARGE WAS ONLY 15 PERCENT BELOW MAXIMUM, MAXIMUM BEING A COMPRESSED LOAD!The lesson I drew is that if you go below tested starting loads you
MAY be getting into S.E.E. territory, particularly with slow powders.
Source:
I`ve always been under the assumption S.E.E was a product of light charges of slow powder along with light for caliber bullets. Tailgunners example of a 45/70, 500 gr bullet with 3031 shoots that all to......
3031 is a middle of the road 45/70 powder though, as far as burn rates go.
Tailgunner how did the guy pulling the trigger fair? The rifle "looks" painful!
No it happened last night after 10 Burritos and a half doz. bottles of Alaskan Amber!!!!
Greenhouse Gases, eh?
BMT
FWIW:
Light loads that are safe to use are listed by Hodgdon as "youth" loads.
Freely available information.
No need to go blowing things up to make up loads.
BMT
I'm no engineer, and when By Smalley (rocket engineer and cartridge designer) tried to explain Secondary Explosion Effect to me, I simply got lost in the explanation. I'm certain that I can't even begin to reproduce his words, but the SEE phenomenon has something to do with reflected wave fronts, harmonic amplification and localized powder heating. I think. The true SEE requires slow powders coupled with a certain amount of airspace and also depends on case shape, IIRC.
Other "blowups" can happen, but are not caused by a true SEE, the cause usually being double or excessive powder charge. The classic blowup is the .38 Special target load of 2.7 Bullseye under a deep-seated wadcutter, except that the burst load probably contained a 5.4 Bullseye double charge.
There used to be a lot more intelligent examination of it in the reloading press. It seems that, as Rocky points out, it has been explained to the satisfaction of those who understand such things, but remains a mystery to those of us in the great unwashed. What I find truly curious is that there exists an editor of a well-known publication who maintains that there is no such thing and that the problem is solely due to those stupid handloaders who overcharge cases.
I`ve always been under the assumption S.E.E was a product of light charges of slow powder...
That's mostly where you hear about it but apparently it can happen with "moderate" charges under certain circumstances. In the .243 example Kikkonen wrote "then new" Norma MRP. I'm guessing a range of loading data was being worked up when the test barrel exploded much to everyone's surprise. So surprised that the test was repeated to verify and one wouldn't risk such expensive equipment lightly. It's anecdotal and apparently an unusual case, but makes for a
BIG caution sign. Note that about everybody would consider MRP too slow to be useful for reduced-loading a .243 WCF.
I don't think there's a consensus on what causes S.E.E. It seems to happen mostly with light charges of slow for volume, relatively hard to ignite powder in big cases leaving a lot of air space. Jacketed bullets which would offer more resistance in entering the bore seem to exacerbate the problem.
I know only what I've read. It's not something that I want to personally experience and exercise an abundance of caution to avoid. Particularly since nobody can define the boundary at which S.E.E becomes a possibility.
If you look at the decades-old data from Dr. Brownell, the evidence for instability in light loads of slow burning powder is clearly present.
He shows a graph of pressure vs. load. In the lower part of the curve, greatly increased pressure variability is clearly present. Undoubtedly, he noticed that effect. But, as far as I have found, he did not comment on it, or what may have caused it.
I have a hard time accepting the notion of pressure waves standing in the cavity, and hold that explanation as tentative. There is just too much you have to assume in order to accept that idea, as far as I can tell. However, SOMETHING clearly happens. Danged if I know what. So I can't criticize that theory, because I don't have anything that is as good, let alone better.
Denton, alternate theory from Kikkonen, slightly embellished, no idea if it's right.
Slow powders with a heavy deterrent coating are hard to ignite. Given a large air space in the cartridge and the powder not necessarily near the flash hole the energy of the primer would to a greater extent dissipate rather than couple into the powder. Further any gas from burning would have more volume in which to expand, slowing the rate of pressure (heat) increase. The powder does not ignite cleanly and "smolders" which produces explosive products of nitrocellulose decomposition. Heat from compression, burning through the deterrent coating, or something else causes chamber temperature to rise and ignite the explosive gas.
In favor of this theory Kikkonen noted that there was something less than a 100 millisecond delay between the primer firing and the explosion in the .243 example. He also wrote that people experiencing what was likely S.E.E noted a slight hang fire.
Again, I don't know.
--- edit
Also in working with very light loads (with very fast powder) I noted a point at which powder residue reduced markedly. This correlated with a small jump in velocity, below and beyond which velocity increased more or less in proportion to powder charge. Not that this necessarily means anything, particularly since it wasn't under controlled conditions.
I`ve always been under the assumption S.E.E was a product of light charges of slow powder along with light for caliber bullets. Tailgunners example of a 45/70, 500 gr bullet with 3031 shoots that all to......
3031 is a middle of the road 45/70 powder though, as far as burn rates go.
Tailgunner how did the guy pulling the trigger fair? The rifle "looks" painful!
He's got a couple fingers that are an inch shorter than normal.
You go real close to his shop on your way to/from work.
The whole thing may never be truly understood - unless and until we find a way to observe what actually happens inside a cartridge. Right now, we cannot. What we "observe" now are merely secondary or even tertiary results of what happened. We guess at pressures based on what effect that pressure has on something else, for example. We observe long-after-the-fact effects and infer a cause, but we cannot directly observe the process at all, much less in anything like real time.
I read long ago that some people who know about such things said it was a detonation instead of an explosion.
A detonation would seem more logical, because considering the chemical construction of powder, it doesn't seem there would be enough stored energy in a small amount of powder to cause that much destruction.
Clue:
Solids like wood, for example, don't burn as solids until initial heat converts 'em to gas.
I used to demonstrate this � back in the days when coffee cans had steel lids � by filling a coffee can half full of sawdust, punching a nail hole in the lid, heating the closed can on a stove, igniting the hot gas that spewed from the hole, blowing the flame out, letting the can cool-off, and finally opening the can to show that the sawdust wasn't even browned or charred � certainly not burnt.
All this takes place with wood over a much longer time than it does with powder.
When you really, thoroughly grasp this principle and assimilate it into your thinking, several ways that the "SEE" can occur begin to become very clear to you. (This isn't the only phenomenon that's part of it, of course.)
123...,
It's not how much energy is in the powder so much as how it's released. Detonation, explosion, deflagration, whichever it is, it happens very quickly, at least faster than the bullet can move (inertia) and make enough space to control the evolving gas.
nighthawk and Ken...
At first blush, that sounds like a more plausible explanation. It certainly requires fewer assumptions.
With all the extra space, the powder would burn more as it does in open air at first. Also, a small amount of oxygen would be available for the first little while.
In Brownell's writings, you can clearly see numerous very fast spikes riding on the normal pressure wave when using small charges. They appear to be fairly regular in frequency, but very irregular in amplitude.
Do you see those spikes with small charges of high nitro-cellolose, single base flake, with the small charges?
This ties to an article I've saved from Precision Loading or Varmint Hunter, IRC.
Going to see if can dig the article up in a little bit.
I like this article; "Mystery Solved," Charles E. Petty, Handloader 187, June-July 1997
Nighthawk:
There is an incident described in Hatcher's Notebook where he was trying to remove a barrel obstruction by firing a bulletless cartridge. The powder ignited, and was trapped in the barrel until the bolt was opened. That is the type of energy I am referring to. The powder gas expanded, but there was not enough stored energy to cause the rifle to blow up. Had there been a detonation, I think the rifle would have been destroyed.
When you have a detonation, there is a shock wave, and this is just my opinion, but if a small amount of powder is the cause of the blow up, it is because of the shock wave that is produced and not the force of the explosion.
The way a shock wave is produced, under certain conditions, instead of an expansion of powder gases, which is the normal function of gun powder when it is ignited and used as a propellant, is beyond my field of knowledge.
The extent of damage caused by an explosion from gunpowder is limited to the bursting of the container, in the event the pressure exceeds the strength of the container. What this means is, you couldn't blow up a building with gunpowder, unless you some how caused it to detonate.
Solids like wood, for example, don't burn as solids until initial heat converts 'em to gas.
Ken
So the thought is the powder is "boiling off" sort of like gasoline and its vapors that will ignite violantly once they have reached a certain density?
Bob, that smith wouldn`t be Bruce?
Well there you go. From the discussion above looks like its going to remain a "mystery" for a lot of us for some time to come. Lots of conjecture but very little scientific fact.
Regards
JohnT
Further in Hatcher's Notebook he describes an explosion caused by shooting into a large container of smokeless powder. Whether detonation or really fast deflagration it must have been impressive! S.E.E. may well describe a detonation, I don't know, but I do know I don't want it (detonation being generally described as producing shock wave propagating faster than the speed of sound).
The point is that the rate of liberation of energy is often more important than the amount of energy. Ferinstance a rifle cartridge filled with a slow powder like 4831 may be just dandy. Fill it with Bullseye and it's a pipe bomb - Bullseye releases about the same amount of energy but a whole lot faster, but does not detonate.
Found the article on a website. Copyright warning there also. Should I just give link, or whole page, appears to be public website.
This article made sense to me, one who has no ballistic, thermodynamic background.
To me he is saying detonation is possible with some pistol powders according to the igniability (not the RQ) of a particular powder in relation to the 'system' limits.
This would explain some of the strange occurences I've been hearing or picking up on with Lil'Gun in some cartridges. A relative new powder, and folks doing things with it, it was not intended for.
[quote] Bob, that smith wouldn`t be Bruce?
Bingo
Has SEE ever been recorded when using ball powders?
I use Greg�s data in several cartridges and it works very well for me. When using fast powders in large cases extra care is required in loading. Alliant Bullseye and Accurate Arms No. 2 work well in large cases.
I have shot his .218 Bee, .25-20 and .25-35 data extensively in my rifles and my data has parallel his.
Not sure, but I think a shock wave reaches about 20,000 FPS, and another property it has is that it is very difficult to stop, if it can be stopped at all.
This ability to try to keep going, no matter what it comes in contact with, is the reason a shock wave is so destructive.
Solids like wood, for example, don't burn as solids until initial heat converts 'em to gas.
So the thought is the powder is "boiling off" sort of like gasoline and its vapors that will ignite violantly once they have reached a certain density? �
Please excuse me, my friend � I'm simply not interested in taking part in a long, drawn-out discussion of this.
always use ninety to a hundred percent of a case-filling charge of your optimum powder
How is "optimum" defined in this sense? Is this basically saying use any powder which lets you fill the case without raising pressures higher than acceptable? Does this work for even big black powder cases, which must keep pressures down in the 20's?
I wondered when someone would mention Greg's work. Based on Greg's data, I load 11 grains of Unique and NO FILLER under a 400 grain cast bullet in my 45-70s for about 1000 fps and extreme accuracy. Load density is extremely low - like less than 10%. The powder supposedly detonates, but maximum pressure is limited by the small amount of fuel (powder) in the case. Whatever the reason, it works. I can shoot these loads all day long without discomfort, and so can my 11-year-old son.
Again, this load is to be used with NO FILLER.
-
this occurs with very light loads of slow burning powder..Proper handloading can totally prevent this.
� always use ninety to a hundred percent of a case-filling charge of your optimum powder
How is "optimum" defined in this sense? Is this basically saying use any powder which lets you fill the case without raising pressures higher than acceptable? Does this work for even big black powder cases, which must keep pressures down in the 20's?
That's right.
Here are two graphs from Brownell's work that bear on the issue. One shows a "spikey" pressure curve that he observed, and the other shows powder charge vs. pressure for 3031. Note that below about 30 grains of powder, the variability of the pressure increases greatly, and that one 20 grain charge produced an unusually high pressure.
Something's going on. Danged if I know what.
I think Bob Greenleaf, formerly of Savage, did an article on this in Handloader several years ago. He was of the opinion that it was due in part to erosion of the throat, causing the bullets to grab, then skip, then grab again (paraphrasing, obviously) which was causing pressure spikes, sometimes using wholly appropriate powder charges and bullets, just in highly eroded bores. It was a very interesting article, but I gave it to a cousin who was having difficulties with a worn .243 at the time, so I can't access it.
I believe the article you are thinking of is; "Mystery Solved," Charles E. Petty, Handloader 187, June-July 1997. This was about PMC and their experiences blowing up a 6.5 X 55 rifle and then blowing the same barrel off their pressure gun. I wrote Dave Scovill about this article and told him I thought it was the article of the decade. Dave wrote back, nice fellow, but I don�t recall what he said.
I read that article, too, but Greenleaf wrote the one I was thinking of, as it was pertaining in particular to .243s in Savage 110 rifles.
Do you remember the year?
It might be as far back as the mid-80s, it was quite a while ago. Like I said, I gave the article to a cousin who needed some info from it.
I used to save all the back issues, but finally cleaned house.
Oh, and it might have been "Rifle" magazine, it was a long time ago, but it was definitely a Wolfe pub.
I found Charles Petty's article that was mentioned. Was on a South Africa website.
Have not had success with Greenleaf but still looking. Could someone give a key word from that Greenleaf article title. Tried .243 as key word with name in combos, didn't work.
As a side note, have seen some brass flow graphs with the .243 Win. The high end loads with that cartridge, and the graphs are spooky, and from some of the brass flow, would not cause much of a spike to blow head severely, guesstimating 5000 psi spike (if detonation happened?, question mark means I just don't know) over max, IF brass flow is maxed at that point. The graphs I saw, were researching anomalys with .243 throat erosion and some blow-ups of safe ammo. Think maybe what Petty is writing about could pertain to some of what perhaps was mentioned by the Greenleaf article.
Do we want to Petty article up here? The link is public domain, not Wolfe.
It is spooky, if you read and understand the possibilities.
Nighthawk has referenced P. T. Kekkonen, who has now passed on, a couple of times. P.T. did give a little more detail on what happened than what has been reported so far.
A main reason of S.E.E. is disorder of powder ignition. Powder charge does not burn after the explosion of a priming pellet. It smoulders like a German tinder, developing a cocktail of explosive gasses like nitrogen oxides, hydrogen (very reactive "In Statu Nascendi" hydrogen - not yet bound to H2 molecules), and carbon monoxide. When this highly flammable mixture of gasses catches fire from still smouldering solid powder remnants, may the "BANG !" be horrible. Mere three grains of gasses may literally wreck the strong .308 Win. rifle action. (Three grains of smouldered solid powder is still three grains of material, despite of it's gaseous form of existence).
Some of the details of the incidents are:
Highest measured detonation pressure was 10 000 atmospheres. A pietzo-electric pressure gauge was broken and highest grade on the pressure scale was this 10 kilobars. A sturdy test-barrel of a German gun-proofing laboratory was wrecked, of course.
This disastrous test was repeated with another set of equipment for the sake of comparison. Pressures of first shots were slightly less than normal. It might be fifth or sixth shot, when the new test-shooting barrel blew up. Again a pressure gauge disintegrated and a scale told: 10 000 atmospheres! It was presumably just a fraction from whole horrible truth, because so called "wave pressure" of a detonation may exceed reading A HUNDRED THOUSAND ATMOSPHERES, when the explosive material is in gaseous form of existence, pre-heated and pressurized before explosion.
Caliber of tested cartridge was .243 Winchester, bullet weight 80 grains, powder then-new NORMA MRP, and the charge... surprisingly... just 15 % less than a maximum (compressed !) load. It was STILL A REDUCED CHARGE DETONATION; not one caused by an excessive charge, because the charge could not be excessive with those components in use. Light bullet and slowly burning powder is not an advisable combination of loading components for .243 Win., known as a caliber prone to S.E. Effect. (It's "big brother" .308 and "kid brother" .22-250 are considerably less risky; last mentioned presumably because of more steep 25 degrees shoulder angle).
Needless to say: All the loading components were examined carefully afterwards. They were faultless. Just the burning rate of powder was selected wrongly for the bullet weight. MRP powder is O.K. for .243 Win., but for the heaviest bullets of this caliber; weight 100 or 105 grains. For the most usual 90 grainer bullets is some more fast-burning propellant advisable.
Noted was a slightly less than a tenth of second lasting delay between hit of a striker and explosion. This same delay is noted also by survivors of S.E.E. accidents, if they can remember something from the "big bang". (Usual recollection is: "I squeezed the trigger and woke up in the hospital"). If the delay lasts a second or more, it is just an usual hang-fire, without signs of excessive pressure.
The warning is the same as what Ken H. has said in regards to using loads of at least 90%.
I have spent a few years tracking the incident down, from P.T.'s reference to
P.S. That story about two broken .243 Win. test-barrels and purposeful courting of S.E.E. in Germany is told in the book "Handbuch f�r den Wiederlader" by K.D.MEYER, who was then a director of German DEVA Institute.
One of the Swiss members of the S&W forum has a copy of the referenced book and provided this translation from German.
For getting a starting-load, orient yourself on rounds with known load-data. Look for rounds with similar case volume and similar bullet diameter and reduce the max.-load of this rounds 25% (better 30%) Don't do this with very progressive powders like f. e. Norma 205, because "underloads", like described anywhere else in this book with this kind of powders can cause S.E.E.
This effect is still a problem for the ballisticans. In the proofhouse of the city Ulm, happened this effect two times in a very short time period. The pressure-measure was dimensioned very big so this part could be used further after the S.E.E. But most of the other parts and the test barrels were destroyed. If fired in a hunting rifle, this load would destroy the rifle in numerous parts.
My information came from one of the 18 parts from
http://guns.connect.fi/gow/QA.html
After rooting thru the back issues of Wolfe, I don't find anything that rings a bell on the Greenleaf article, but I distinctly recall it being in an older issue, before they went to color pictures, so it was quite awhile back. I don't know if Greenleaf is still around, he'd retired already from Savage when he wrote that article, but I've seen an article of his in TVHM a few years back, regarding something else altogether.
Paul5388...
Informative post. Thanks. Pretty much supports the theory put forward by Ken Howell earlier.
I think P.T. was describing something akin to a miniature fuel/air bomb of a similar variety to what was used in the OK City bombing. There was a dispersant/atomizer and a subsequent igniter. There was also a similar methodology used in Viet Nam.
In relation to the S&W forum issue, it seems to be predominantly a rifle phenomenon, involving slow burning powders with not too greatly reduced loads.
In handguns, it seems more likely that double or even triple charges and/or multiple projectiles and/or bore obstructions account for most Ka-Booms. Other factors can be involved, so the list doesn't have all the possibilities, but there were sufficient "and/or" to get the point across.
always use ninety to a hundred percent of a case-filling charge of your optimum powder
How is "optimum" defined in this sense? Is this basically saying use any powder which lets you fill the case without raising pressures higher than acceptable? Does this work for even big black powder cases, which must keep pressures down in the 20's?
I would have to say that filling "big black powder cases" with black powder would be a safe bet.
This has been a CRAZY year for all sortsa' off the wall "B.P. Substitute / Equivalent load data.
Great thread, all,....really enjoyed this read.
GTC
I would have to say that filling "big black powder cases" with black powder would be a safe bet.
Certainly, but as you point out, people do try all sorts of equivalents. I've wondered if any of those involving smokeless powders are safe.
I can see where a hang-fire might generate some gases which later go off, these gases forming something of a super-primer. This would light up the main charge far faster than a regular primer, and the result would be similar to having used too fast a powder, ie. the entire charge burns off before the bullet is far enough down the bore.
However, I'm not sure I see why a light bullet is required in the recipe. Does this mean the light bullet jumps down the bore a bit more, giving a larger (and cooler) combustion chamber, allowing more gases to cook off? If so, then a heavy bullet should have a similar effect if the charge is reduced further still.
always use ninety to a hundred percent of a case-filling charge
Is Hodgdon playing some odds in advocating greatly reduced charges of H4895? How about the BP folks shooting light charges of 4227 and 4198 in the medium length (eg. 38-55 and 45-70) cases? Or is it only the heavily deterred powders which create problems?
One theory I have heard is that when using slow or hard-to-ignite powders, the primer spark itself can propel the bullet forward lodging it in the rifling before the powder actually ignites, which makes the lodged bullet act like a bore obstruction. It would seem a lighter bullet would be more prone to this. It would also seem that low bullet pull would contribute as well. This is why I carefully brush-out any dry lube from case necks before seating new bullets. As a rule, I also do not use light-for-caliber bullets or light charges of slow powders.
-
There may well be something to that, BR. And the rougher the throat, the worse the "obstruction" might be. There IS a correlation of these events to rifles with worn or dirty throats, so maybe...
The only quibble I have with your post is the word "spark" because the primer does a whale of a lot more. It's quite the small-scale explosion, in fact. The primer alone can generate over 3,000 psi and temps of over a thousand degrees.
Okay, I stand corrected. You must be retired or something.
-
"The Genie's Bad When He's Mad"
Always liked the title to that Chapter . . .
. . . and I plagiarize Dr. Howell.
It's doesn't cover SSE, but covers internal ballistics (IB) as much as I care to know about it at present.
Ken, I thought you were coming out with a new one on this topic? Did you? If so, where is it available.
A single bullet cannot act as a bore obstruction in the usual sense. Read Hatcher.
Alternate theory, and I emphasize THEORY. I don't know.
Assume that the idea that incomplete ignition produces enough heat to decompose nitrocellulose into a mix of explosive gas but not enough temperature to ignite the gas (Kikkonen again, more or less) is correct. Pressure rises as slow decomposition continues and eventually the compression raises the temperature above the point of ignition (diesel effect). Ignition propagates through the gas almost instantly and BOOM!
Now allow the bullet to move forward. The volume of gas increases but there's more space for the gas to occupy. Less compression, less heat, cooler gas temperature. Perhaps the gas never gets hot enough to ignite and the bullet pops out of the barrel.
Ok, now the bullet encounters some resistance to its movement. Could be rifling, rough throat, additional friction from being copper jacketed or whatever. The bullet slows appreciably, space for the gas to expand doesn't increase as quickly, pressure, compression, and temperature rise. Possibly to the ignition point of the gas.
As far as bullet weight, remember that in the .243 WCF fiasco the powder was SLOW FOR BULLET WEIGHT. Heavy bullets have greater inertia and are slower to move forward, allowing less room for gas expansion. Pressure and temperatures rise more quickly and the nitrocellulose is quickly and completely decomposed.
Let me emphasize this is all pretty much guesswork, but seems to fit (so far).
The hard part in thinking about this is that it all happens very fast, much faster than things in our common experience. Even the slowest event is over in less than a tenth of a second. And that is much slower than the normal course of events, where the round fires properly.
I've seen a number of pressure traces with secondary peaks along the bullet's travel between case and muzzle, apparently caused by rough or constricted bores. None of these secondary peaks was nearly as high as the maximum peak that kick-started the bullet from its stock-still position in the tight grip of the case neck. The bullet was, of course, already moving pretty fast when it encountered the rough spot or constriction along the way.
It would be fun to design experiments to see just what's going on if someone would cough up a couple hundred grand to equip a lab. Don't think it'll happen since SEE doesn't come into play with reasonable loads. As I read it Kikkonen got into it because Europeans wanted subsonic loads for .308 WCF and the like to use with their silencers, and curiosity over European WWII gallery loads. I experimented with very light loads (with unjacketed bullets and the fastest powder I could get) out of curiosity. But it was pretty much pointless with .22 rimfire standard, subsonic and CB caps available.
I've been out of town for a few days and didn't have a wireless connection.
I think you'll find the use of "guard" loads (reduced power practice loads) were actually in existence in the US also. Most of these "guard" loads were for .30-06 and other rounds, that existed around the turn of the 20th century, very much prior to the introduction of the .308 WCF.
I actually use quite a few subsonic loads, i.e. 12.0 gr of Green Dot in .45-70, that are much more useful than a .22 rimfire of any sort.
