Oops!

0.243" diameter bullets, NOT 0.0243".

Thanks,Red,I often wondered why I had headspace questions with this sporter.The history of the rifle by it's date 8-18 and it's cartouches,marks,indicated it was a Canadian Army 30.06,POW guard or home guard,that it wasn't much used.The barrel is sharp,the accuracy is so good it sounds boastful.But that tip is filed off, allowing the rifle to fired before the bolt fully closed, hammering the receiver.I,too,am lucky and have a soft not brittle receiver.The steel is" 31/2 % Nickle Steel" the same alloy as pre-war M-70s.
If you Successfully fill your tag the first day,all you can do the rest of the hunt is sit in camp and drink beer

Was the brass cleaned in a tumbler? Could there possibly be a piece of walnut shell lodged in the flash hole causing a delay in combustion, resulting in an excessive pressure spike. As Old Actions post says - something fell or crawled in, it wouldn't have to be very large and you would not notice a difference in the charge volume. This has been my thoughts as I read through the posts.

I have just been re-reading all the posts and it has reminded me of a couple of experiences I have had which relate to rifle blow up. I reloaded for a .243 years ago by loading up 5 rounds each of differnt increments of powder and taking 20 rounds to the range each night to test them. On one of these evenings I got to the range and met a father trying to teach his son (age about 12) to shoot his 30/06. The kid was almost in tears from the pain of the recoil and his father couldn't understand the kids problem. I explained to the father the difference in recoil between a .243 and /06 and offered to let the kid shoot my rifle. They agreed and after two shots the kid complained that the .243 hurt too much. I advised them that they should wait until the kid grows some more before he trys shooting a large bore again. After they left the range I sat down and proceeded to do my shooting. First shot, damn this thing kicked, must not have held it properly. Second shot, double damn it really was kicking too hard. Packed up, went home and started pulling bullets. The ones the kid and I had fired had 5 gr. more than the load I had been loading for. Scared the crap out of me. How could this happen? At that time of my reloading career many writers were stating that you should always re-set your powder scale every 10 rounds to make sure the scale has not changed. I had re-set the scale wrong. Lesson learned - set the scale and leave it alone until your finished loading and always check the volume of powder in the cartridges when they are in the loading block so you can get a visible comparison in all cartridges. This later resulted in catching loads that varied when using a powder measure and coarse powder. A few granules of powder were sometimes hanging up in the powder measure due to using the small diameter drop tube for the .243. The rifle used was a "poor man's Weatherby" Voere Shikar and the powder used was IMR4064. This powder has always been quite forgiving in my estimation, by showing small increases in pressure and 4895 would show little or no signs and add a half grain more and pressure would instantly skyrocket.

Pyrotec, You know, I can't think of any bolt action which utilises a bolt requiring one full turn for lock-up, either. The P13,14,17 bolts have a spiral cam locking lug surface and seat. The rate of advance is generally given in the ammount of movement lengthwise in terms of one complete revolution or 360 degrees. In most receivers I have measured this is equivalent to a lengthwise movement of .100" in a complete revolution of the cylinder- bolt body in this instance. It is also eqivalent to the pitch of 10 threads per inch of length. Reloading dies of the common standard are 14 threads per inch.A full revolution causes a lengthwise movement of
.0714, and .007 movement is one tenth which is 1/10 of a 360 degree circle which is 36 degrees. It is not unusual for a reloader who does not wish to change a seating depth on his bullet seater to simply add a fraction of a turn to the seater in the press for a short run with a longer bullet to achieve desired depth or ctg.OAL and then change back to his permanent setting. I thought that giving that sort of degree = thousandths description would be understood. Red has received several posts on "his" thread about this. He has patiently answered in true gentlemanly fashion in a manner that I would really have to work at to accomplish as he has done in his replies. To get the lug seat pocketing which he describes in even the lowest hardness M 17 receiver implies the brass squirting like a liquid, or failing that the print would have vanished on the head of the case,
if the brass had a soft head. It would give first, and as it did so increase the volume of the envelope, and in most instances NOT pocket the lug seats of the receiver in the process. The results which he quite adequately describes are usually termed in ordinance circles as a detonation, and that term does not mean that the extreme pressure in one end of the vessel is the same as that in the other end, nor does it mean that you count the greatest pressure as that which did the deed. You can, however, suspect that the wall of pressure in wave form moving toward another pressure wave of lesser intensity, and meeting it somewhere will increase exponentially in intensity of pressure because it has hit a wall of increasing resistance and that result in turn confining the higher intensity end to become even more violent in its confinement,and this because nitro cellulose burns ever more faster under pressure increasing as the retardent coatings on the cylindrical bodies is burned off. Blasting engineers have used this principle for years to enable the use of a pick-up load of "powder" ( powders- plural) to achieve the desired effects once requiring a semi-load to duplicate. A common way to graphically illustrate this principle is to pitch rocks through the still surface of a water pond causing ripples and note what happens when the 2 sets of ripples collide at the point of collision. It is even more interesting if there are floating objects at the point of collision. It is a very long way from all of the factors in play during an undesired ctg detonation but it is a start in the direction of understanding.

downwindtracker2

Glad that my comments were of some use or interest. When you said earlier on that your cases stretch 11 to 13 thou on firing, is this in overall length, or in the head to shoulder length? Either way, it sounds quite a lot, more than could be accounted for just by firing with the bolt handle raised slightly. Have you had the chamber checked with headspace gauges? If not, I feel that you would be well advised to hunt out a gunsmith with the appropriate gauges and get it done, so you know where you stand with it.

> If you Successfully fill your tag the first day,all you can do the rest of the hunt is sit in camp and drink beer

It�s a bit different over here � the deer season is 24 hours a day, every day of the year, with no license and no bag limit. Most hunts start with some hours walking, almost invariably uphill, with all your supplies for the duration of the hunt on your back. You gotta be either super-fit or a devout alcoholic to take beer with you. (I�m neither, so I drink tea when I�m in the bush!)

shortshot:

> Was the brass cleaned in a tumbler?

No. As I have previously said, the cases in that group were only on their second firing, and they were still bright and shiny. After the first firing they were wiped over on the outside with No. 9 on a rag, and the insides of the necks were cleaned with a stiff nylon brush. Then the necks were lubed inside and out, and re-sized, after which all traces of the lube and No. 9 were cleaned off. (inside and out)

> something fell or crawled in, it wouldn't have to be very large and you would not notice a difference in the charge volume.

This is not totally impossible, but I think it�s highly unlikely. Straight after I had re-sized and cleaned the cases, I cleaned the primer pockets, re-primed them, filled them with weighed charges, and seated the bullets, all in one continuous session. The ceiling and walls of my basement workshop are lined and painted, and are not dripping with dust and dirt, and I wasn�t tossing any loose materials around in the midst of doing reloading. I actually keep the place quite clean most of the time, as workshops go, because my wife gets annoyed if I tramp metal swarf, filings, sawdust, and other such debris into the rest of the house, and grind it into the carpets. Women can act a bit funny about things like that :-)

I suppose a small insect or spider MIGHT have crawled into one case between the time I primed it and when I seated the bullet, but what do you think the chances of that occurring are? Very slight, I would think. And what effect would it have, anyway? Its body would probably consist of more water than anything else, and on firing, may actually reduce the amount of heat generated by the powder burning (and hence the gas pressure) rather than increase it. Though this is just intuitive guesswork on my part.

Today, a neighbour of mine took some photos of the blown 6mm case with her new digital camera, but they came out rather blurry. However, one of them - the best of a bad lot - may suffice to illustrate what happened to the case.

Question: How do I find a site to �host� the photo so that I can display it here? Can anybody help me, please?

Red

When I was much younger I loaded a case full of Bullseye to see what it would do to an old Carcano rifle. I fired it by remote control (string on the trigger) from behind a barrier, and the result was much like what has been described in these posts.

redrover---

As it stands now and without seeing the pictures I'd say there's two main possibilies---

1) The cartridge was lacking in support. This is my favorite therory as of now. I don't have a P-17 here to measure but I've seen the same thing on a M-70 and, of course, on badly done M-1911 colts. If the safety breech angle is wrong the case is unsupported too far up the case.

2) This is a combination..... and without a microscope and other testing gear to actually examine the brass with, it's just a guess.

Either the brass failed due to metallurgical defect from normal pressure, OR the case failed due to a high pressure spike.

If the brass was defective I think it can be seen under magnification, but probably not proven enough to have recourse against the maker.

If a high pressure spike it could be--

1) Wrong powder,
2) Wrong charge,
3) Wrong bullet,
4) Wrong bullet tension,
5) Bore obstruction (including grease or oil),
6) Wrong headspace.

There could be other, but more unlikely causes, but that seems to sum up so-far the possibilities.

Last week I was loading surplus 4831 with a Redding BR measure. Fifty grains is right up to the neck, but three out of the hundred had partial charges in them from the powder log jamming in the drop tube.

It only take one of those (and incredibly bad luck) to fragment a nice rifle.

Red,here tea is traditional in the bush,too.I like gator-aid or coffee.
The P-17 is a difficult rifle to headspace because of the advancing lugs.To check headspace,one must take apart the bolt and gently see how far the bolt closes. On a 30.06 +.006" is No-Go.Mine almost closed.Since I have a Lee trimmer and trim each time ,I had a base line for case overal length..013"-.011" =.002 is the difference between a tightly closed bolt and a sloppy one.
I was puzzled by the extra .005,so I gave up and had the rifle rechambered to 308 Norma Mag,a better fit than 300WinMag in the standard box.
Now I have to add that safety tab to prevent the set back again.Thanks,again,Red.

Redrover go to www.momentoffame.com and go to the "Hunting" section and follow the directions to post a new picture. It's free, and more importantly dead easy for even a computer illiterate like me.

JBelk; You may have hit on it with your last paragraph. Add to that the post by System98 on pressure wave and ,possibly,there it is. At a range here in Bc several years age I saw a custom 1911 blow up. It was similar to your rifle.Jammed up,mag blown down and out and violent recoil. As with you,luckily the shooter wasn't hurt. The conclusion everyone there came to was a short charge causing an overtraveling flame front from the primer,igniting the short charge too quickly. Conveging Pressure waves? Horrible over pressure results in horrific damage. Just a thought,the most important thing is that you weren't hurt,thank goodness. derf

Based on the description of how the gunsmith removed the case and opened the bolt, I am inclined to go with Jack Belk and either a case softness or rifle problem or both in combination.

In terms of a reduced load causing the problem, I have a couple difficulties buying that argument.

Firstly I have used reduced loads in about all formats and extensively for the last 30 years and without any problem. I realise of course if the reduced load trouble area is only a 1 in 100,000 thing then my own experience may not mean too much.

However, I think I can add some "theory" which supports my own experience. The major problem that sometimes occurs with reduced loads occurs when loads are worked up with powders that are too fast for the calibre and in combination with a big case capacity and especially with Winchester ball powder. What happens is that you get hangfires that are so small as the shooter does not notice them. The effect of the hangfire is to reduce the pressure and hence allow the shooter to keep increasing the load. This in turn allows a charge of powder to be used that in fact is too great when ignition is correct. However, as the charge is increased a point is reached where proper ignition takes place and then of course you have an over load.

So let us say we are going to work up loads with a powder like Varget in a 338/378. Before we start we need to calculate what the maximum load of Varget is likely to be, based on other loadings with appropriate powders like H4831 etc. Let us say that 85 grains of Varget calculates as a top load with 200 grainer in 338/378. If the rifle is showing very low pressure with perhaps 82 grains then we have an ignition problem which is a causing a false reading of the pressure of that load.

I don't buy the argument of over ignition of powder because of the powder lying flat due to half a case of powder. It is my understanding that when ignition is correct then all powder granules ignite together and the burn rate is controlled by each granule of powder rather than the rate at which the powder is set fire to. In other words it is totally different to the iginition of the fuel air mix in a car engine.

It might also be worth mentioning that for many years Dupont published full pressure loads for all their powders and for all calibres, including such combinations as 4227 and the 264 Winchester with 140 grain bullets.

Mike

Mr Burgess:

More questions:

What exactly do you mean by �lug seat pocketing�? I am trying to fit the term into what I have written about my damaged Enfield 6mm, and/or what downwindtracker2 and I have written about his Enfield 308 Norma Magnum, and I�m not succeeding.

What can cause detonation, as opposed to more or less controlled, progressive burning of the powder charge in a cartridge? Assuming that the charge consists of a normal quantity of an appropriate powder, and everything else is as it should be.

What causes these transient, very high pressure spikes you spoke of earlier, and what effect do they have? If they are typically of a duration which can only be measured in pico-seconds (10 to the power of minus 12, or one millionth of one millionth) and they do not register on a copper crusher pellet, how much direct effect do they have on a hard brass case head?

Can you give me references to research into this subject, investigating how these transients and/or rolling shock waves are alleviated by using full length sized cases? Or created by using neck sized cases?

Mr Belk:

Thank you for your concise summary. I think I have already said all that I am able to about each of these possibilities, so there is no point in repeating them.

I have saved all the targets I have shot testing loads and groups with this rifle since it was re-barrelled, and I have the full details of each load written on them. When I checked back, I found that I had in fact previously shot two five shot groups with the load that blew up. (100gr Sierra, moly coated, 42gr of H4350, standard WLR primers, re-formed Norma 7X57 cases, neck sized) Prior to that, I had tried the same bullets un-coated with 39, 40 and 41grs of H4350, in the same cases, etc, and 40 and 41grs with coated bullets. No visible pressure problems with any of them. The groups were inconsistent, though � some were less than an inch at 100 metres, while others were much larger. This has been typical of all bullets heavier than 70grs which I have tried in that rifle. No signs of bullet instability, and there shouldn�t be, either, as the barrel has a twist of 1 turn in 10 inches. Frustrating!

I�ll try posting a photo of the damaged case tomorrow (our time) though I'll warn you now that it is not very clear. If it is too fuzzy to be of any use, I'll try to get something of better quality.


BECoole:

Quote: No, You TURN when necking up, REAM when necking down! Think about where that brass is going in each case.

By the term �donut�, I mean an anular ring in the inside of the case neck, at the neck/shoulder junction. Is this your understanding of it also? If it is, I can�t follow the reasoning behind your statement above � maybe YOU should be thinking about where the brass comes from and goes to.

The conventional wisdom � usually supported by fact - is that the brass in the shoulder portion of a new case tends to be thicker than it is in the neck of it. If you neck a case UP, part of what was previously shoulder becomes the lower part of the neck. Full length sizing the expanded case forces any extra thickness of brass to the inside of the neck, forming a donut, and the action of an expander button or expander mandrel often does NOT push all of it back to the outside of the neck, where it can be removed by neck turning. This problem is often encountered when making 6PPC cases from Lapua 220 Russian brass.

If it is considered essential to get rid of any trace of the donut, inside reaming the neck does the best job of it. This may need to be followed by outside neck turning to obtain uniform necks of the required thickness.

When necking a case DOWN, part of what was the lower portion of the neck becomes part of the shoulder. This does not in itself tend to create a donut, though it can form later, with successive loadings and firings of the case, but this can occur with ANY case, re-formed or not.

Fjold:

Thank you for the information on how to post pictures here � much appreciated. I�ll give it a try tomorrow.

Red

Red, The only way to keep this from going to string 3 is to E Mail you. Bill Leeper up across the boundary "fence" from me, has come the closest to putting what I have said together. I used the word "pico" because that is what the H-Bomb builders like to use for the sequence of events in a thermo-nuke happening, or how fast the
molecules,atoms ,ions or whatever it is on the readable part of the sun's surface to indicate temperatures at one time they stated were like unto 44,000 degrees F. It is no doubt a far out of date reckoning, but on the other hand just as no one has actually been there thermometer in hand any more than the ballistics engineers seem to have no actual recording from inside a small ctg case as to temperature the actuality is still up for grabs. Mili might be too coarse,nano better.

Mr Burgess:

Quote: "The only way to keep this from going to string 3 is to E Mail you."

OK if you wish. My email address can be found under the envelope shaped icon at the top of my posts.

I certainly do not want this topic to become anything remotely like the length of the one on the �Reloading� forum about Sierra Matchkings. God forbid! I gave up reading that thread many months ago.

However, if you have some hard evidence, such as laboratory tests, that prove the phenomena you have referred to really do exist, caused by the factors you state and producing the results you suggest, then I�m sure that many readers as well as myself would like to hear about them in more detail. The phenomena I refer to are:

1 Transient high pressure spikes of very short duration and large magnitude. I am not clear whether you claim that these are CAUSED by the use of neck sized cases, that they are PREVENTED by using full length sized cases, or that using F/L sized cases simply attenuates them to a non-destructive level.

2 Sympathetic and/or colliding pressure waves. Same questions as for (1) above.

3 A powder charge detonating instead of burning progressively. (assuming a normal load of a suitable powder) What causes this, and what can be done to prevent it?

Quote: "Bill Leeper up across the boundary "fence" from me, has come the closest to putting what I have said together."

Does he? His statement that he considers the case neck to chamber neck clearance I was working with to be quite OK, and not a contributing factor to the case head failure I experienced, directly contradicts what you said earlier on. He makes no attempt to explain or elaborate on what you have said about pressure waves and/or spikes, he merely states that something like that MAY have been the cause of the failure.

I�m not trying to stir up a fight with you in public - or in private - and I do not aspire to become an authority on the subject of internal ballistics. I am simply wanting to get a clearer picture of the theories you have proposed, and also, establish how well they have been proven and what their implications might be for persons like myself who simply want to load their own ammunition for hunting and target shooting. (and who do NOT want to have their rifles �spontaneously disassembling� in their hands)

I have heard enough reports of rifles blowing up as the result of firing loads consisting of extra light charges of slow burning powder to convince me that this a dangerous practice, and it is one that I make every effort to avoid. I don�t pretend to understand all the theories that purport to explain WHY these blow-ups occur, though they have already been debated at enormous length on darned nearly every shooting forum on the internet, and doubtless will be again in the future. I hope this thread does not become another one of these debates � if it does, I�ll be out of it, except possibly as a �lurker�.

Red, Sent an E-mail 17.5+ hours ago, It may be lost in the ether, and another failure in communication for me. Wasn't it Carlyle who said something to the efect-- "He convinced against his will,unconvinced remains him still"? When that happens I look at it as a failure in communication on the part of the wannabe convincer. I see little point in trying for three.
I suspect I was never cut out to be a missionary anyhow. I sincerely hope that this sort of thing does not befall you ever again. Regards