Detonation Anyone?

[390ish]

Had a scary experience yesterday. 1905 Ross commercial chambered in 30-40 Krag. Shooting 28 grains of 5744 behind a Lyman 210 gc per the Lyman #4 cast manual. Pulled the bullet from my box where it was seated nose down. First shot gave the below results. Had been shooting 200 grainers with 40 grains of IMR 4350 all last year with really good results.

http://i236.photobucket.com/albums/ff206/390ish/rossbarrel.jpg

http://i236.photobucket.com/albums/ff206/390ish/IMG00092-20111031-1754.jpg

[ku4hx]

Dang! I'll assume from your coherent posting and pics of your hand that you're OK which is always a good thing.

Not 100% sure what you mean by "Pulled the bullet from my box where it was seated nose down." but if the cartridges were stored loaded nose down I'd suspect the powder got "stuck" up against the boolit's base and you had a classic case of detonation.

[elk hunter]

Scary doesn't even describe that. Are you OK?

Is that 28 grain 5744 load a Lyman recommended one? If so I'd call Lyman and tell them what happened.

[flounderman]

I have heard it is possible to assemble a ross wrong with bad results. by any chanch had you taken the gun apart and reassembled it?

[firefly1957]

I intentionally blew up a Siamese Mauser with a similar size 8MM case by loading it with Bullseye and it did not do that much damage. I was close to two hundred yards away when it went off that is about how much 17 pound line that that reel held.

[390ish]

Had to get one piece of metal taken out of my face. My forehead looks like I got shot with rock salt. Nothing permanent. Went into shock and passed out at the range, but I feel fortunate.

I am really going to miss that rifle. Shot it for a number of years with nothing but cast for the last three. I could have done a better job with my post as far as description -- I had the loaded cartridges pointing down in the box before loading. I was excited about trying boolits from this mould and did not think about powder position before loading.

Notwithstanding what happened, I think the 30-40 krag has to be one of the best cast cartridges out there and I think a Ross in decent shape is a superb rifle. I guess these things sometimes happen.

Funny that it is a straight pull action and although the receiver went into chunks, the bolt stayed in place. From what I read, it was supposed to be a remarkably strong action. Mine was not one of the models that could be re-assembled incorrectly. Think that was the MKIII that came in the higher pressure chambering options.

[376Steyr]

Since it happened on the first shot, I have to wonder if your 28 grains of 5744 wasn't something else. Glad you survived.

[felix]

A SEE can happen any time, any load, with reasons unknown. We know most of the conditions to avoid are not recognized as such because of minor violence. A load with high variances on target is one situation which is overlooked often. ... felix

[flounderman]

have you pulled a bullet from the remaining loaded shells and examined the powder and weighed the charge?

[390ish]

Powder is the same size as RL-22, but a bit darker. Looks the same as what was in the cannister of 5744 I still had on the bench after I got back from the hospital. Weight was spot on. I just have a hard time believing this happened with 5477, this about the only application for this powder. I sent Johanne at Accurate powder an email. Maybe he will have some ideas, he knows his stuff. Maybe I should have used a tuft of dacron filler. I just have never done that with a bottlenecked case -- have done it in the past with 38-55 loads.

[Hang Fire]

I have heard it is possible to assemble a ross wrong with bad results. by any chanch had you taken the gun apart and reassembled it?

Ditto on that, the Ross rifle design has a name for flaws, I would not fire one, period.

[390ish]

The bolt stayed put. The rest of the rifle went away. On some Ross rifles you could assemble it so that the lugs locked to the receiver, but the lugs were not locked to the bolt. The bolt would come flying back. Never took my bolt apart. It was a pain to take in and out of the rifle because the lugs were spring loaded and wanted to spin while trying to get the bolt down into the receiver.

[autofix4u]

Following this with intrest, I burn a lot of aa5744. The only issue I have ever had is some unburned powder left in the barrel and excessive smoke at low pressures.
My concen is that 28 grns would be at or above max for 30-40 size case. I cannot find any load data for 5744 in the 30-40, but the 7.62x54r is close and I find 28grs as max with a 200grn boolit at almost 40k psi. What is the max pressure for 30-40?.

Glad that you are ok, and I feel your loss of a nice rifle.

[uscra112]

That's a real shame, and I'm glad you weren't too much cut up.

The only coherent explanation of SEE I've ever read, and the only one supported by experimental evidence, is that it's a form of hang-fire. The initial primer pressure unseats the bullet and lodges it in the bore, followed by the eventual ignition of the powder behind what is now a bore obstruction. Low fill ratio is said to aggravate the hangfire, especially with hard-to-ignite powders. But 5744 isn't that hard to ignite, and lead boolits move so much more easily than jacketed that I would find it hard to state categorically that SEE was the cause of your blowup.

28 grains of 5744 in a 30-40 case is about 65% fill ratio, so a simple double charge doesn't seem likely either. But Quickload says your 28 grains is a pretty hot load with that heavy boolit. And 5744 doesn't flow through volumetric dispensers all that well. If you weren't weighing every charge, a partial hangup that dumped into the next case could have overcharged that case. Just two grains more and you had a 50K PSI load. Three grains and you had a 53K PSI load. Four grains and you're almost 60K. Did you find any of the remaining rounds with a below-normal charge?

Would be interesting to look very closely at the remains of the barrel, assuming you even found them all. That's "old metal", and evidence of an incipient crack in the chamber could be looked for.

[BCB]

I too have burned plenty of 5644 in the 223, 270, 30-30, 44, 445, and the 7-30 with no problems like that—thankfully…

As far as SEE, well, there are many opinions of that critter. I have read articles with much information. The main indication through all of the articles indicates slow burning powders. This I don’t know, and I don’t think 5744 is a slow burner…

Some even question SEE…

I think many times when something happens, as you show in your pics, it is just a good out to suggest SEE…

My opinion is that there was something very mechanically wrong with that rifle OR there was an obstruction in the barrel…

The 4th Ed. of Lyman does recommend the load you were using—but it is a maximum charge—yet, I doubt even a tad above maximum would do that type of damage…

Obstruction is my guess…

Good-luck…BCB

[Bret4207]

I'm with BCB, investigate the remains and look for a bore obstruction. You had a hot load to start with. Do you have mud daubers in Va.? I'd check all my remaining rounds.

Very sad and frightening way to lose a fine rifle. There's nothing wrong with the Ross design or materials at all. Glad you're okay!

[excess650]

My 10 year old lot of AA5744 flowed through the measures just fine. My new lot from 2011 tends to bridge in the same measures, so I'm very careful with it.

I use 29gr behind a 200gr Saeco #301 in my 30-06 with the old lot, and consider it a heavy load for cast. Recoil is noticeable, and I wouldn't consider putting the same charge in the smaller 30-40 Krag case.

In that 5744 has a high nitroglycerine content to minimize position sensitivity, I doubt that it was SEE. More likely would be just a high pressure load combined with a 106 year old rifle.

The early '03 Springfields have questionable metallurgy, so why not the Ross?

Mud daubers in Virginia? Yeah, they have 'em, but if you keep your doors closed and screens in the windows they stay OUTSIDE.

[Wayne Smith]

5744 bridges so badly in my measures (RCBS, Lyman 55, Pacific) that the only one I'll use it in is my Belding and Mull.

[405]

First, glad you'll be OK! Couldn't care less about the rifle.

5744 is a relatively fast but bulky powder. This, to me, does not at all sound like a SEE. Except that the end result looks the same.

I shoot a lot of 5744 in old original 30-40s including a Krag and two Win 95s. Old guns are old guns and they all have unknown histories and are most assuredly not as strong as modern guns even of the same design. The SAAMI max limit for the 30-40 is 40K CUP/PSI and that 28 grains under the 200 gr bullet according to Lyman data is flirting with that limit.

I looked at my 5744/30-40 load data recorded when working up loads for the Krag with a 187 gr GC bullet. My data indicate-- 23 gr of 5744, 1893 fps with a vel SD of 11 fps. Notation at bottom, "medium high pressure" that based on indicators on the case and subjective senses like sharpness of report, vibration and sharpness of recoil. I know it's not scientific but those indicators were telling me, "this load is entering the caution zone".

Bore obstruction is always possible but my pure WA'd guess is that load flirted into the danger zone once too often with a gun of unknown history that could have had cumulative metal fatigue issues.

[OnHoPr]

I kinda have the similar thoughts of firefly1957. That's pretty extensive damage if you look at the whole piece of barrel, barrel housing and straps of the action and the bolt, even if you look at it with a higher load.

405 40K CUP/PSI is an inaccurate or misprint. CUP is not the same measurement as PSI, it is one or the other. The two styles of measurement can not be placed or construed to the same numerical statement. IMO

[Judan_454]

Im glad you are ok,it looks scary. But its good that you posted these pictures because it lets us know not to take safety forgrated even though we have been reloading and casting bullets for years.
Dan

[Sonnypie]

I don't think you can shoot that pop-stick any more.:-(

[Mk42gunner]

Glad you didn't get seriously hurt. As to the rifle; it's like I told my daughter after she wrecked my new to me 15 year old truck (three weeks after I got it)-- "Things can be replaced, people can't."

Robert

[Brithunter]

The Ross 1905 is a totally different beast to the Ross M-10 or model 1910 which has the multi-lug cannot breech bolt lock up and which is the the one if you try really hard and are fairly daft you can put the bolt in incorrectly.

I believe Ross Seigfried (spelling) did an extensive test on this some years back.

A nice commercial sporting rifle in 280 Ross is still a serious desire for myself.


The only other rifle I have seen photos of destroyed like that using case bullets was a Swedish Mauser and it was discovered that he had somehow gotten a double charge in one case with the next but one case having no powder in it at all. He did a magazine article about it and has the ruined action mounted on a plaque above his hand-loading bench as a constant reminder to be more careful.

[405]

I kinda have the similar thoughts of firefly1957. That's pretty extensive damage if you look at the whole piece of barrel, barrel housing and straps of the action and the bolt, even if you look at it with a higher load.

405 40K CUP/PSI is an inaccurate or misprint. CUP is not the same measurement as PSI, it is one or the other. The two styles of measurement can not be placed or construed to the same numerical statement. IMO

I'm fully aware of the difference between PSI and CUP. But, the Lyman manual clearly states the SAAMI MAP for the 30-40 round is 40K CUP. Additionally, just so happens that the two different pressure measuring systems "cross paths" mathematically at very close to 40K. :)

No matter, the gun didn't blow up because it was too strong or from too little pressure :)

[390ish]

I really appreciate the input. Not looking to blame anyone or anything. Just trying to figure out what happened. That rifle would really shoot before it went away. Pulled the fourth shot in this 100 yard cast string:

http://i236.photobucket.com/albums/ff206/390ish/krag100yds.jpg

When I first got it I ran about 2 boxes of factor 180 grain through it for brass. I never had any pressure signs from the 40 grain IMR loading I used all last year. The top load was the velocity I wanted, so I decided I would try that for accuracy and work down if needed. That might have been the wrong move with an old rifle. Everything I had read stated these were strong actions. I am no scientist, but this does not look like an action failing -- it exploded. Went through two pairs of jeans I was using for elevation and blew through the side of the booster seat I was using as a rest. The range I use is on an uphill grade. 5477 looks to be too fast for a detonation. I did not run a patch through the bore that day because I had done it about two weeks earlier -- I do a check on the bores of my milsurps about 2x per month to keep away rust. I was not happy with the neck tension on these loads.

I had annealed the brass before this loading and the gas check really opened the necks. I had to use the crimp on my seating die to lock the bullets into place as there was not good neck tension. If cycling the action caused a projectile to fall into the case, what would happen? Think it would cause an explosion? Seems like the powder would blow by or not fully ignite in that scenario. I am just thinking of possibilities. I might leave the cast bullets to handguns for a little while.

I will take a photo of the brass case and the steel fragments folks saved for me and try to post tonight.

Whatever I did, make sure not to do it yourself!

[405]

Well, this can go around and around with no definitive answer. The only thing to do is take a bunch of educated guesses and lay out the most reasonable possibilities. No, the action in and of itself did not give way-- as in stripping bolt lugs off or tearing out the lug recesses. But judging by the photos the receiver ring fractured. High velocity gas then does its thing on exposed parts. There is really no readily visible difference between a strong action letting go at really high pressure and a compromised or weaker action letting go at 40K +/- CUP.

Don't know about a bullet that has dropped into the case body?? Doesn't sound good for sure but have never personally tested it. :shock:

But in your recount of having to crimp the bullet tight... that did set off a small light bulb with me. Also, since you have loaded these carts before with upper end loads they have likely stretched a bit. Any possibility that they could be too long for the chamber and you were able to chamber them because of the tight crimp? If that is the case then that crimp is running up against the end of the chamber thus HARD CRIMPING that bullet in place. It doesn't take much to do that... only a few thous. I know from experience that WILL spike pressures. Since you are up near max with these loads anyway, ANYTHING that bumps the pressure up could be the "straw that broke the camel's back". None of the above is anything more than a SWAG and you may never know for sure the root cause. Wish these were easier to pin down!

[BOOM BOOM]

HI,
Glad you are ok.
Sorry about your rifle.:Fire::Fire:

[303Guy]

Any possibility that they could be too long for the chamber and you were able to chamber them because of the tight crimp? That's a logical question to ask but looking at the sample target I would say no. Reading between the lines I would say that 390ish is an intelligent person who knows what he is doing. I'd suggest he would have noticed if something was wrong with pressures - especially if the groups were poor and there was barrel leading.

The possibility of bridging might be real (that's speculating on my part). Any chance of a boolit being deposited in the throat by an empty case and an assumption made that a spent case had not been ejected? (Don't laugh - I did that! OK, do laugh. It was really dumb! I tried hard to chamber the next round! Only the incompressibility of the powder charge saved me from blowing the gun up).

It does sound like a 'detonation' should not have occurred. But it did somehow - well an extreme pressure spike akin to a detonation occurred anyway.

390ish, might I ask you to post more picture of that shattered action? There is the interest factor on how actions might fail plus the morbid fascination factor.:wink: And than you for giving us the wake-up call!:drinks:

Last but not least - real sorry about the loss of your rifle. :sad:

Your face will heal but .... it's not like Ross rifles just lie around in the fields! :mrgreen: :drinks:

[badbob454]

Glad you are ok ...

[Wayne Smith]

How did you anneal the cases? This is highly consistent with Hatcher's reports of Springfield actions failing because of a series of too soft brass. If one case got annealed too low you created just that scenario.

[Ragnarok]

Makes me wonder if the action was on edge anyhow..maybe cracked or chrystalized...same for the barrel...combined with loads on the edge of maximum..she came unglued!

The possibility exists for something in the bore too..a patched jag came unscrewed...rifle's muzzle hit the dirt..leading in the throat..etc...Probably never know for sure why the gun ripped like a bomb.

[390ish]

I will try and use my wife's camera to take better photos of the action. I do have one so-so photo of the recovered brass:

http://i236.photobucket.com/albums/ff206/390ish/IMG00098-20111031-1944.jpg

The ballistician at Accurate Powder said that it is nigh impossible for 28 grains of 5477 to detonate. He implied that things can get more squirrely with cast bullets at pressure than jacketed because there are usually a few more variables, which sounds right to me. I am going to quit trying to figure this thing out and be as attentive and methodical as possible without taking anything for granted. I did not consider the issue of annealing -- yet another factor. I do know the length was right on all the cases as they did not require a trimming from the last firing. I annealed before resizing. At the end of the day, I created a situation that made too much pressure for that rifle, so the whole thing is definitely on me. Will post some better action photos. Thanks for the input. Take care.

[Char-Gar]

I am no expert, but I have a couple of observations about the issue.

1. It is clear the rifle came apart due to way over the top excessive pressure, but why the excess pressure?

2. You don't show a pic of the barrel, but if it was a bore obstruction the major rupture point would be in the barrel, but in your case it was the chamber and action that came apart, so I would opine that is where the pressure was.

4. In Hatcher's notebook, Gen. Hatcher details trying to blow up 03 Springfields by firing loaded rounds with a bullet stuck in the barrel. After three or four rounds behind the obstruction, the barrel was bulged but not ruptured. A barrel obstruction is a good way to ruin a barrel, but not likely to produce a destroyed action.

5. Having a bullet shoved back into the case will drastically increase the chamber pressure. So one should never load a round that does not have proper neck tension. Run a magazine load of rounds through the action into the chamber to make certain all if good and bullets are not being shoved back.

6. This annealing stuff is way over done and is rarely needed. If done wrong, it can produce a case to soft to contain the pressure.

5. Of course there is always the possibility you had too much powder or the wrong powder in the round. This is by far the most common cause of rifle blow ups and just by math is the most likely cause.

I am sorry about the loss of a fine performing rifle, but very glad you were not seriously injured. I do hope you can get a definitive answer to the issue, so it won't happen again.

[390ish]

Sent the photos to the ballistician at Accurate Powder. After looking at them, he thought that it went beyond a question of the pressure that could have been generated by a load of 28 grs of 5477 and that he that the level of destruction points to a metallurgical failure. Obviously the pressure was too great for the rifle. Maybe it would have blown this last time with the IMR loads or factory loads I have used in the past, I don't know.

I have a fair number of C&R rifles. Shot a "new" 1916 94 Swede for the first time right before setting off the Ross IED. Did great with J-word 160 grainers. Makes me want to magna-flux the receivers on all of the oldies, especially an 8mm lebel I have not yet fired.

My wife has a professor at University of Virginia who wants to look at the scraps of the receiver through the department electron microscope. She told him what happened and he got all excited and started talking in scientific/pinhead/patois about crystalline shear and so on. He is going to email me. I would call that informed morbid curoisity.

[Larry Gibson]

A bore obstruction is an intragal part of an SEE. It is cased as described by uscra112. In this case the load was a maximum for 5744, it was loaded with the powder in the forward part of the case, the primer force drove the bullet into the leade where it was stopped (i.e. the bore obstruction), the 5744 then ignited. Most powder's burn rate is reall accellerated if confined. In this case the burn of the 5744, being on the slow end of the fast burning powders, probably was really accellerated to very high psi before the bullet could get moving and the psi exceeded the capacity of the case to contain it.

This is very reminicent of the documented SEE using 2400 in the 45-70 case in a Contender where the barrel was pointed down and then raised to fire.

I use a lot of 2400 and 5744 but if I'm pushing cast bullets to top end I prefer to use a medium or slow burning powder. The same velocities can easily be achieved with less psi, a slower time/pressure curve and usually better and mor consistent accuracy.

I'll add that 5744 does bridge in many powder throwers. I damaged an action using such because 5744 bridged. I was interupted and did not do my usual visul inspection after charging the cases. Murphy caught me as it happened the one time I failed to check and I fired the "heavy" load first. I found the light load by pulling the bullets and checking.

I do now use a dacron filler with 2400, 5744, 4198 and 4759 BTW. I have found velocities, psi's and accuracy to be much more consistent.

I shoot a Ross Mark X in .303 quite regualrly. Mostly I shoot a 311299 over 4895 with a dacron filler. However, I have loaded jacketed 150 gr bullets to some pretty inmpressive velocities while staying within safe psi's. Given the "improved" size chamber of the Ross and the 29"+ barrel it sneaks up on standard '06 velocities. Like 390ish I don't take the bolt apart and have no problems with it. Glad he wasn't hurt that bad and thanks to him for his honest admission in providing the information here.

Larry Gibson

[oso]

Glad you didn't lose more than you did.
How many rounds left from this batch? No matter how many, I'd pull each one and check each remaining charge. Please.

[9.3X62AL]

While threads concerning this subject scare the living daylights outta me, I find myself drawn to them anyway--mostly to see what can be learned.

First--I AM GLAD YOU'RE ALL RIGHT, 390ish. I'm not sure how comfy I would be getting behind another rifle stock after having an experience like yours. I've managed to avoid any such incident (so far), and hope to keep that record intact. Knock on wood.

[leadman]

The older Accurate #2 loading manual lists a load with a 210gr boolit and 5744 at 25grs max.
Don't think 10grs of boolit weight should make that much difference in pressure.
Out of curosity I filled a 30-40 case to the top with 5744 and weighted it. 57grs, so a double charge is out as you would not be able to seat the boolit.

I have found errors in loading manuals before so it pays to confirm the data from a couple of sources and start low. In one incident the starting data proved to be just about max.

Anyway, I'm glad the OP was not injured more seriously. Hopefully the testing of the metal will give some clue. I would be pulling all the loads apart and weighing the charges and see if the powder did bridge.

[TheGrimReaper]

DANG!!! I hope you are okay.

[frankenfab]

While threads concerning this subject scare the living daylights outta me, I find myself drawn to them anyway--mostly to see what can be learned.

First--I AM GLAD YOU'RE ALL RIGHT, 390ish. I'm not sure how comfy I would be getting behind another rifle stock after having an experience like yours. I've managed to avoid any such incident (so far), and hope to keep that record intact. Knock on wood.

Yup, I have been all over this myself.

[Ragnarok]

Go over to the Gun Zone site..and dig around for M1A failure in the articals..you will find a few pics of a destroyed M1A rifle and another artical by the Fulton armory M14 guru(Clint McKee?)..with some structural analysis on the M1A's destroyed barrel. The barrel in this instance was was bogus..was improperly heat-treated to begin with..and over it's lifetime developed cracks at the land/groove junctions.

While the barrel on the M14 ripped like a banana peel from the breech forward..the similarity's to this cool old Ross's blowup stick in my mind...maybe it ain't the ammo?

From what I can gather the Ross was never made in .30-40 Krag, but was .303, .280(giant Ross), and .370(whatever this cartridge is?) and a couple other calibers...I dug around online for an hour googeling Ross rifles..and find no mention of Ross rifles being chambered for .30-40 from the factory.

So somewhere down the road this particular Ross got rebarreled. Just how good a barrel was this barrel?...Who made it?

[uscra112]

My wife has a professor at University of Virginia who wants to look at the scraps of the receiver through the department electron microscope. She told him what happened and he got all excited and started talking in scientific/pinhead/patois about crystalline shear and so on. He is going to email me. I would call that informed morbid curoisity.


NOW yer talkin' my language ! (Engineerese.) I've had access to an X-ray CAT scanner capable of not only scanning a cast iron engine block but also measuring the features it sees inside to an accuracy of a few microns, (in 3D). Ran a few receivers through that before they got too busy and started to ignore me. I've had scanning CMMs that could map a chamber against a CAD model to less than a micron. But an electron microscope - MAN am I jealous !!!

[390ish]

As best I could tell, this was a military model with a commercial stock because the stock had not been much messed with outside of some cosmetics. Not really shaped like the military stock, as I used to have one of those in 303 and traded it.

I took more photos, but with my phone again. My daughter was playing with the camera and it is now missing. One of the shots is the remnant of roll mark/stamp. This rifle was rechambered in 30-40 Krag and stamp read "CAL 30-40" and the gun retained its factory barrel, which was undoubtedly 303 british. The barrel retained the crossed pennant proof with the "C" mark from Canada that matched other Ross rifles on line. I never slugged the bore, but it shot cast bullets sized 311 very well.

Did only so-so with factory 30-40 ammo.

Partial caliber stamp:
http://i236.photobucket.com/albums/ff206/390ish/calstampross.jpg

Front view of action -- some washout from flash on broken metal:
http://i236.photobucket.com/albums/ff206/390ish/action1ross.jpg

Barrel views (3):
http://i236.photobucket.com/albums/ff206/390ish/barrel3ross.jpg

http://i236.photobucket.com/albums/ff206/390ish/barrel2ross.jpg

http://i236.photobucket.com/albums/ff206/390ish/barrel1ross.jpg

Pieces people picked up and gave to me:
http://i236.photobucket.com/albums/ff206/390ish/scrapsross1.jpg

Reverse view of pieces
http://i236.photobucket.com/albums/ff206/390ish/reversescraps1ross.jpg

The one in the lower left has crack, if that matters. My wife gave the contact info for the professor with the electron microscope. I talked to an engineer buddy today and he said it would not be difficult for a person (metallurgist) with the know how to tell if the metal had become plasticine over time giving rise to a crack or if the stress causing the break occurred all at once. I have probably run about 200-225 rounds total through the gun in the three or so years that I owned it.

[303Guy]

Holy cow! I didn't realise the chamber had blown. My late Uncle was the workshop manager at Musgrave in SA and he told me of a 308 cartridge being fired in a 270 on their test range and that the receiver split open and let the barrel go downrange. He said the barrel was undamaged i.e. re-usable. (The boolit hit the target). This was a test range so the gun was fired remotely so no safety issues.

In that instance there was extreme excess pressure involved. For a rifle chamber to burst like that? Not bulge or or distort then pop, just crack open like it was brittle. A gun barrel isn't brittle normally. It's tough but not hard. Unless of course the pressure spiked as in a detonation - then even softer steels would shatter. So could it be a true detonation? Could this happen again to someone else in another gun?

[Larry Gibson]

Got to say the way the chamber was blown that there was indeed a bore obstruction. Hard to say whether from an SEE event, 2 bullets in the case (possible from 390ish's earlier description of loose necks) or some got into or was left in the barrel. Very reminiscent of an M16A2 that blew....had a jag with patch left in the bore just in front of the chamber. I'd lean more toward 2 bullets inadvertently put into the case..........glad 390ish is basically alright. Too bad about the rifle.

BTW; I shoot a Ross Mk10 .303 quite often and don't take the bolt apart. It takes healthier loads than the SMLE but I keep psi's down in the 55,000 psi range. Rivals the '06 with 150 gr bullets having the reamed out (basically improved) chamber and the 29"+ barrel length.

Larry Gibson

[390ish]

Only only one bullet was seated in the case. Loading was accomplished about 2 hours before firing. Two bullets in a case would be silly. My supposition was that upon seating, the crimp on the bullet may have broken and the bullet slid down into the case.

Larry, do you load to 55k psi range with cast in Ross, or is that with jacketed bullets? I have been unable to determine if the proof rating of 62k psi on the 1910 model holds true with the 1905 model. Do you know?

This rifle had a 303 Brit bore rechambered to 30-40, which is smaller in diameter and with lower pressure than the 303.

[excess650]

I'll be curious to hear the results from the autopsy, but it sure looks like crystallized (brittle) metal to me. Steel from over 100 years ago is far different from the steel we've become accustomed to using in rifle barrels and receivers. Too, heat treatment has come a long way. I wouldn't be surprised if that old Ross was just case hardened, but just speculating.

The pictures from the phone are way better than some guys' camera photos.

[Larry Gibson]

390ish

"Larry, do you load to 55k psi range with cast in Ross, or is that with jacketed bullets? I have been unable to determine if the proof rating of 62k psi on the 1910 model holds true with the 1905 model. Do you know?"

That 55 psi is with jacketed bullets. My cast bullet loads with 311299 and 4895 with a dacron filler are around 23-25,000 psi depending on the flavor of 4895.

Understand that the 62K proof rating on the 1910 model is in C.U.P. "psi's". That is a much different figure these days using piezo transducers and strain gauges. I would suppose the 1905 used the standard .303 proof load(?) but that is just a guess. Perhaps some of our Canadian members know?

Larry Gibson

[303Guy]

I've seen a 22rf barrel split from the breach end a few inches along.

I can't help thinking there was nothing 390ish did that could have cause this. On the boolit being pushed back into the case, would that possibly have pushed pressure into detonation zone? The boolit canted so it could not move down the bore?

Then, assuming there was a bore obstruction, would there be enough energy from the charge to blow the gun? It was a lead boolit. It could have swaged and been flame eroded? Where did it go? It would be interesting to know if it hit the target or just got mashed and flame cut. Is there any sign of lead dust in the bore?

You know 390ish, as curious as this is it is not really fun. Seeing a fine rifle like that destroyed in seconds is actually quite sad. Of course I an greatful that you were not seriously injured, but the loss of that rifle ....

[390ish]

Thought I would update those of you who are interested.

I heard back from Tom Griffin at the Lyman laboratory. He said that he "tended to agree" with Johan at Accurate powder on this being a metallurgical rather than an overpressure issue.

"Hi Spencer,

Thank you for the additional info. Glad to hear that you did not have any serious injuries. From the damage that was done, it could have easily happened. It is really a shame that this happened to such a unique rifle also. I wish that I had a definite answer for what happened, although I would tend to agree with Johan. With the added safety factor of the rifle originally being chambered for the higher pressure 303 British cartridge, it would seem likely that the charge would have needed to be well over 28 grains to get into a serious pressure problem. I would not want to try to speculate on what charge would be needed to get up to the 45K, 50K, or 60K area, but would think that the case would be close to filled. If the professor does examine the metal, I would certainly be interested to know the outcome.

Tom"

[Southron Sanders]

First of All, I am Glad that you are O.K.

You might never know what caused your gun to blow up. Personally, I would never shoot a Ross.

Replace your Ross with a "High Number" Springfield '03. They are safe and the '06 can be loaded with cast bullets.

[Rokkit Syinss]

Glad to hear you're not seriously hurt. Some of the fractured areas look to have different coloration but that could be the fact you're using a phone to take the pics. The discoloration however does look similar to some fractured metals I have seen. Stress corrosion cracking maybe?

[303Guy]

I was looking at those discolourations too. Note also how the fracture at the chamber end has multiple faults. And why would the top piece break off at the thickest part of the barrel like that? Why not just bend up?

[390ish]

Engineer buddy of mine looked at it today. He is a retired mechanical engineer who worked at oil drill sites. He really cued in on what Rockkit Syniss said. There was oil that appeared to penetrate some of the crack sites. He thinks that the barrel may have been screwed into the receiver too tight. I don't remember all the terms he used, but in a nut shell, it started out as one or two small cracks that grew in a slow, linear nature.

The way he explained it was that the steel retains much of strength, even when it is cracking, then it reaches a point where it just completely fails. He thought that the crystalline look of the breaks was suggestive of the ductile steel being worked over time to where it became brittle. Thought that bad heat treating would not have lasted as long it did on a rifle and that it likely came from overtightening the barrel. I guess when it was re-chambered someone likely took the barrel off and then over tightened it, or just turned it in a rotation when there was not enough room for it, then rechambered.

On the plus side, the pan lube that I made up seemed to work well. Only a hint of leading in the barrel, and that might have been left over from the old liquid alox rounds I used previously. Going to head back to the range tomorrow and get my head right again.

[303Guy]

I understand the mechanism of under-tightened bolt failure and also of over-tightening thread stripping failure but a chamber shattering from over-tightening? I'm afraid I will have to disagree with the over-tightening hypotheses. The edge-line of the thread is visible in one of the photo's and I see no sign of thread damage, let alone from over-tightening. In all my years in the engineering field I have not seen proof of over-tightening failure of that nature. It's cyclic stress that causes stress fatigue failure and over-tightening does not do that. Under-tightening does. Well, over-tightening something to the point where it gets strained into the failure zone will cause a failure but that won't be longitudinal. I'm just saying I don't thinks so.

[geargnasher]

I tend to agree with 303Guy. It's been a long time since I did any substantial amount of failure analysis, but it looks to me that if the barrel was overtorqued in the receiver, the receiver would have failed and the barrel would simply have been blown forward as the receiver split. But it seems that the failure originated in the forward part of the chamber body, just ahead of the end of the receiver. It sure looks like Cosmoline seeped into some of those cracks, question is did it do so before or after the Kaboom?

Could be fatigue cracks from abuse in a previous life allowing the chamber metal to finally give up the ghost all at once, or it could be the boolit acted as an obstruction somehow.

Gear

[Larry Gibson]

+ another on 303Guy's comments. This is a very plain example of destruction from a bore obstruction.

Larry Gibson

[243winxb]

Powder problem - to much or wrong kind. Bore Obstruction-Bulged and/or split barrel. One or the other.

[BCB]

Powder problem - to much or wrong kind. Bore Obstruction-Bulged and/or split barrel. One or the other.


In one of the very early posts on my part, I said a bore obstruction--period...

I assumed he used the powder he listed--if not, then the wrong powder factor comes into play as stated by 243winxb...

It is just plain and simple...

Sorry engineers, sometimes we don't need to get to the atomic level of composition and structure to figure out what the problem might be...

If you’re holding a stick of dynamite and someone lights the fuse, we don't need to understand how or why dynamite explodes but we understand where you end up!!!

Sorry for the rant, but facts are sometimes facts...

Glad no one got hurt...

BCB

[uscra112]

Are the remains still going to UVA for the SEM analysis?

[390ish]

I am still waiting to hear back from my wife's professor. He told her Thursday that he would respond to my email here soon. He told her that one of the professors there used to do a fair bit forensic work on metal issues as an expert witness, but he is no longer there. She says that he has two big classes and no teaching assistant, so it might be a little while before he puts it under the big magnifying glass. I am a dumb lawyer and have a very good handle on what I did, but no real idea as to determining why this happened.

I did go to the range yesterday. Shot fine with a rimfire pistol. No so well at 150 yards with the Enfield. I am glad that after a week's time I no longer look like I went bird hunting with Dick Cheney. :grin:

[oso]

Good to hear you're back in the saddle.
I also hope you have time to pull the remaining rounds to check if there is one with a light charge. I'm just so insatiably curious I'll do it for you if you don't have the time.
My curiosity may be due to an unforgettable event about 3 pm 12/20/2004 while chronographing a test load of some decades old lot of W540 in a 38 Super. Boolit was a Lyman 356637 153 grains, C.O.L. 1.265", Win brass, PMC small pistol primer, air temp about 30 F.
First shot was 835 fps (in the expected range), second shot recorded was 429 fps and the third shot was way over pressure with over expanded brass and completely flattened primer but head stamp still legible. That shot was wild to say the least and not recorded on the chronograph.
I wasn't reading each velocity, but that low one may have tipped me off had I noticed it. That lot of powder didn't have any clumping that I could find, but there may have been static cling in the drop tube or something causing a lite charge followed by a heavy charge. The remaining charges were O.K. No further problems with that powder and boolit, even increased the charge, but I now routinely clean my powder measures with Dawn or fabric softener and check for spider webs and whatever. And I'm still at least curious.

[303Guy]

I developed the habit of placing all powdered cases upright in the shell holder tray and shining a torch down them all to check and compare levels and make sure they have powder in them.

[mpmarty]

Me too but I use a halogen desk lamp shining down into station 3 on my Dillon 550B.

[Rokkit Syinss]

I developed the habit of placing all powdered cases upright in the shell holder tray and shining a torch down them all to check and compare levels and make sure they have powder in them.

I use a mini maglite.

[uscra112]

I use a mini maglite.

Me, I weigh 'em all, no matter how long it takes. Only trickling the last tenths of a grain into the pan makes me feel safe and secure. Having thrown and weighed thousands upon thousands of charges, I trust measures about as far as I can throw a Buick. One-handed. And no case gets a charge until the previous one has its' boolit seated.

[geargnasher]

I developed the habit of placing all powdered cases upright in the shell holder tray and shining a torch down them all to check and compare levels and make sure they have powder in them.

Last time I used a torch to check powder levels I got a black face and no eyebrows!! :kidding:

Regional semantics are always interesting to me, I'll bet the term "flashlight" sounds kinda weird around your area.

Gear

[swheeler]

What I know for sure and for certain, SEE's happen and dacron is cheap. Glad you are OK!

[303Guy]

Are you saying Dacron will prevent a SEE? I've detected a dramatic reduction in pressure and velocity by firing a gun straight down with a 75% load density and no filler. (Neither values were actually measured, just summized).

I still chuckle at the torch comment.:mrgreen:
Well OK, I have a good laugh! We do know the term 'flashlight' and a torch is a thing with a flame on it but it produces light so ... [smilie=1: But it was funny!

[Marlin Junky]

I went right to the bottom of this thread after reading the first couple of posts, so I apologize if my post is out of context. However, QuickLoad indicates that load produces 45K PSI. Couldn't that be just too darn much pressure for this type of firearm, especially considering it's age?

MJ

[Larry Gibson]

If we understand what SEE is (it is not "detonation") then we understand how dacron can eliminate one of the factors that contributes to SEE. I have posted the Handloader article numerous times that explains what SEE is, how it happens and that it is very reproduceable in labs......or your gun if you want.........

If you can't find the article using the search function I can repost it.

Larry Gibson

[405]

I went right to the bottom of this thread after reading the first couple of posts, so I apologize if my post is out of context. However, QuickLoad indicates that load produces 45K PSI. Couldn't that be just too darn much pressure for this type of firearm, especially considering it's age?

MJ

Yes,

That's what first came to mind when I started following this thread. May never know 100% for sure the cause, but I'm still giving odds that is the most likely.

[390ish]

No word from the professor guys. Thought I would provide an update.deer season starts Saturday. Might take the M-39 with some cast Lee 200s or some j word factory silver tips and the 358 Savage. Don't have a mold or even dies for the 358.

[Capn Jack]

I had a shortening of the C.O.A.L. caused by a build up of lube in the seating die really cause chamber pressures to spike.

Why not a set back caused by recoil. I've had that caused by loose crimp on a .223. Luckily in both cases the rounds hung in the magazine.

Jack...:coffee:

[uscra112]

No word from the professor guys. Thought I would provide an update.deer season starts Saturday. Might take the M-39 with some cast Lee 200s or some j word factory silver tips and the 358 Savage. Don't have a mold or even dies for the 358.

Thanks for the update.

[303Guy]

If you can't find the article using the search function I can repost it.
I'd appreciate it if you would. Thanks, Larry.


QuickLoad indicates that load produces 45K PSI. Couldn't that be just too darn much pressure for this type of firearm, especially considering it's age?Not really, I should think. The locking lugs did not fail. The chamber walls do appear rather thin but the failure appears to be a shattering which is is suspicious (to me).

[Larry Gibson]

Here's the "copy". If you want an actual scanned copy of the article PM me with you email address and I can send it that way. The copy here is verbatum from the article, it is just missing the pictures.

Larry Gibson

Mystery Solved


Handloader- readers have doubtless heard of a term called secondary explosion effect (S.E.E.). It is a theory that attempts to explain the catastrophic failure of some rifles while firing seemingly reasonable handloads or reduced loads using slow-burning powders. Theories have been offered and debated in these pages and elsewhere, but they have been just that, theories, because no one has been able to reproduce effects under laboratory conditions. The purpose here is not to debate S.E.E. but rather to report on a specific incident and the results of tests done to discover the cause of catastrophic failure.

One of the great problems with attempting to theorize on the cause of catastrophic failures is that we must do so after the fact. We have the corpse, usually with some parts missing and must try to figure out what went wrong. Learned theories are offered, sometimes conflicting, and we end up with a bunch of folks shouting in print, 'You're wrong.' "No, you’re wrong." Since the event they're arguing about what without benefit of instrumentation, either one could be right. The events I describe here represent the first instance of an event produced under controlled laboratory conditions and documented on industry standard pressure measuring equipment that provides a plausible explanation offered to explain S.E.E.

The following is simple. It goes all the way back to Shooting 101 where we learned that bore obstructions blow up guns. There are no explosions, no mysterious wave amplifications; it's just a case of several factors, combining in worst case conditions to create a bore obstruction with the bullet.

In early 1989 a major manufacturer began development of a load for the 6.5x55mm Swedish that was to be added to their product line. Development was uneventful and all work was done using the copper crusher pressure measuring system, for there were no standards established for piezo-electric pressure measurement in the 6.5x55mm. The copper crusher method of pressure measurement has been with us for generations, but it is not without its limitations. The results obtained are not true "maximum" pressures, and it provides only a single data point. There is no way that one can deduce what is happening during the period the powder is burning, nor can one see other significant ballistic events.

A quantity of ammunition was loaded using a relatively slow-burning, non-canister propellant with a 140-grain bullet. After load development in ammunition manufacturer’s pressure guns, it is common practice to function test ammunition in a variety of available rifles to ensure satisfactory performance before it is released for sale to the public.

As function testing of the 6.5x55mm ammunition was begun using Swedish Mauser rifles, they noticed some of the same signs of excess pressure every handloader is taught to look for - flattened primers, enlarged primer pockets and heavy bolt lift. All the ammunition fired in the pressure gun had been perfectly acceptable, but SAAMI test barrels and chambers are made to tightly controlled specifications so the first supposition was that some element within the test gun was contributing to high pressures. Then a "spontaneous disassembly" occurred that destroyed the action but left the barrel undamaged. The bore was clear and showed no bulges. It was immediately identified as a high pressures failure and an investigation was begun. The barrel from the wrecked Mauser action was fitted with a collar that allowed it to be mounted in a universal receiver, and an industry standard conformal piezoelectric transducer was installed. Another test was performed using the Oehler Model 82 piezoelectric pressure measuring system equipped with a trace hold oscilloscope.

(Fig !)
round pressure (psi) velocity (fps)
1 48,820 2,601
2 53,849 2,662
3 57,609 2,708
4 57,999 2,720
5 54,093 2,687
6 58,634 2,731
7 62,150 2,754
8 82,120 2,875

Pressure tests are commonly done with a 10-round string and as you can see from the chart, pressures increased very gradually on rounds I through 4. At the fifth shot, pressure dropped and then continued to increase until, at the eighth shot, pressure, went to 82,120 psi; and the technician wisely stopped the test. The raw data was then used to prepare additional graphs (fig. 1) which show that, after ignition, pressures dropped momentarily to near zero on the graph before beginning to rise again.

To interpret this data we have to first understand the ground rules applicable to pressure testing with conformal transducers. The key term here is 'offset" which relates, primarily, to the specific cartridge and the brass used therein and must be determined for each transducer and lot of brass. The offset is the amount of pressure required to obturate the case to the chamber and begin to exert pressure upon the transducer. In this case the offset was 3,800 psi so when we look at the time/pressure curves produced in the test; we must understand that we are not actually seeing pressures below the level of the offset. There is a distinct dip in the curve, however, shortly after the pressure begins to rise when it drops to a level somewhere at or below the offset pressure. All we can say for sure is that, at this point, the pressure is <3,800 psi. Engineers calculated that for the specific bullet being used it would take pressure of at least 5,000 psi just to keep the bullet moving.

As I said, there are a number of variables at work here, but the main culprit is a very long leade or throat erosion. It takes relatively little pressure to eject the bullet from the cartridge case (de-bullet), which produces a significant increase in volume. Unless the rate of gas production is fast enough to keep up with the increase in volume, pressure must drop. The simple equation is PIVI=P2V' where P = pressure and V = volume. It is helpful in considering the phenomena reported here to view the rifle barrel and chamber as a cylinder whose volume is determined by the position of the bullet at any given point in time. If the bullet is moving, the volume is continuously increasing until the bullet exits the barrel.

If P2 is at or below the pressure required to keep the bullet moving it must stop. Then we run into our old friend inertia. Bodies at rest tend to remain at rest, but all the powder burning behind the resting bullet doesn't know about that. It keeps burning and pressure rises. Sometimes we get lucky and the bullet starts to move and relieve some of that pressure, but in a worst case of a rough bore and/or soft bullet it doesn't, and pressure continues to build until something else lets go. Most of the time this will occur around the primer pocket and gas will be released through the flash hole, but we're talking about events that are taking place quickly (milliseconds); and if pressure rises at a rate faster than it is being relieved, a catastrophic failure is inevitable It has been theorized that many 'accidents" represent a combination of effects which combine, in worst case conditions, to produce a catastrophic failure. Robert Greenleaf (Rifle No. 146) presents convincing evidence to show that conditions rarely remain the same, and the condition of the barrel and throat combined with different bullet characteristics can produce markedly different pressure levels for the same load. This is certainly seen in this data where a series of eight shots of the same ammunition delivered pressures ranging, and steadily increasing, from 48,820 psi up to 82,120 psi, at which point the test was stopped. We can, from looking at this test data, presume that all rounds (except perhaps the first) displayed some degree of temporary bore obstruction, but that the bullet was blown out of the barrel. Fortunately universal receivers are capable of containing considerable pressures, and it is certainly possible that the pressure generated by the last shot would have wrecked a standard rifle.

One factor that cannot be accurately measured with this data is the possible contribution of fouling from the bullet itself. It seems reasonable to assume that some accumulated fouling was blown out on the fourth shot, which accounts for the drop in pressure at shot No. 5.

When the engineers were able to examine and expand the time/pressure curves produced during this test, it became obvious that each shot showed a pronounced drop in pressure very early in the ignition/burning cycle and, on the shot where the pressure reached 82,120 psi, it dropped to the baseline before resuming a climb to the stratosphere. It would be easy to think that the fire went out, but a more reasonable explanation is that the burning rate of the powder became even slower. We know that pressure is a major component of the burning rate of any powder, and it depends upon adequate pressure levels being reached and maintained. In fact, what is shown in this case is that the amount of gas being generated was not sufficient to keep the bullet moving. If pressures drop below some optimum level, burning slows down and is often incomplete. Of course there will always be a quantity of unburned powder from any shot, and this observation has led to some of the conclusions regarding S.E.E.

In order for the pressure to rise to catastrophic proportions some other adverse conditions must also be present. These involve the cartridge case, the bullet, chamber and barrel and need to be discussed individually.

Bullet pull: We know that an adequate amount of tension between the case neck and bullet is a prerequisite for uniform combustion. This term, called bullet pull, is independent of the firearm and is routinely measured in the factories. Crimps may or may not be used to increase bullet pull, but most centerfire rifle cartridges depend primarily on tension between the case and bullet. If you've ever committed the sin of firing a cartridge into which you have neglected to dispense powder, you know that the primer alone is perfectly capable of propelling the bullet several inches down the barrel. Pressure generated by a primer alone can be as much as 4,000 psi in a conventional centerfire rifle cartridge; so it is certainly possible, in a normal round, for the primer impulse alone to be sufficient to get the bullet moving before little if any pressure has been generated by the powder charge.

Chamber: In the area of the case neck there must always be some clearance between the case and the chamber wall, but if this area is too large there is little resistance and the bullet can be released with very little pres sure behind it.

Condition of the barrel and throat: The impact of conditions within the chamber and throat are difficult for the handloader to analyze, and a throat that appears normal under cursory inspection may be revealed to be rough and irregular when seen through a bore scope. Greenleaf's report (Rifle No. 146) details how pressure increased as the number of rounds fired through a test barrel grew larger. This can only be attributable to a deterioration of the throat and leade on that particular barrel. In this instance SAAMI standard barrels were used and showed no irregularities, and it was only when the same ammunition was fired in a 'field' barrel with more generous tolerances and wear in these areas that problems were seen.

Bullet hardness and stiffness: The shape and construction of the specific bullet used can be a major factor in the levels of pressure developed by any given load. Bullets undergo some degree of deformation as they enter the bore, and the force required for them to engrave the rifling and obturate to bore dimensions can vary considerably.

Temperature: We know that pressures tend to increase as the barrel heats up, and a round that produces perfectly normal pressures from a cold barrel might show signs of excess pressure when the barrel is hot.

Work presented here answers questions. Some of the findings support theories offered to explain S.E.E. some don't. We haven't, for example, seen any evidence to indicate that there is ever an explosion, and many authorities doubt that there is. Perhaps what we need is a better name. Taken to its most basic component, what we have is that most fundamental cause of catastrophic failures: a bore obstruction. The difference here is that the offender is the bullet itself effect rather than some external source is both predictable and reproducible in the light of this new evidence, but it is highly dependent upon a combination of factors that produce disastrous results. If one or more is absent, everything will probably turn out fine; but when all come together, pressures rise and, sooner or later, sooner or later, something will fail. While it would appear that slow-burning powders contribute significantly, until now we didn't exactly know what to look for. I think it's at least theoretically possible for a bullet to stop in a barrel if the other conditions are bad enough with propellants other than the slower grades.

Have you ever fired a load that you had used often and suddenly gotten signs of excess pressure such as difficult bolt lift or flattened primers, and then fired another that seemed perfectly normal? I think this happens with some frequency, and our normal recourse is to shrug our shoulders and also be a bright red flag waving in keep on shooting; h6wever, this could front of our nose that is telling us that something is wrong. In the light of these findings, it could be telling us that a bullet did a stutter step before it went on out the barrel. The question then becomes what should we do about it. My first suggestion would be a careful investigation of the condition of the bore, especially the throat or leade to see if there is any erosion or roughness followed by thorough cleaning. A chamber cast might be in order to get precise measurements. If the barrel shows obvious signs of wear or throat erosion, the cure is obviously to replace it or set it back and rechamber. If the barrel appears to be within specifications, however, a change of bullet or propellant may be enough to solve the problem. The importance of this information is that it explains, with laboratory documentation, what can happen when the wheels fall off in the worst way. It seems like such a reasonable answer to many of the mysterious ka-booms that good reloaders have had with good handloads, and it is something we all need to keep in the back of our minds in case we encounter something out of the ordinary. While the data here was generated using the 6.5x55 Swedish cartridge, the observations are not specific to that round. They could occur with almost anything.

[FirstBrit]

[QUOTE=Larry Gibson;1464615]


(Fig !)
round pressure (psi) velocity (fps)
1 48,820 2,601
2 53,849 2,662
3 57,609 2,708
4 57,999 2,720
5 54,093 2,687
6 58,634 2,731
7 62,150 2,754
8 82,120 2,875

Pressure tests are commonly done with a 10-round string and as you can see from the chart, pressures increased very gradually on rounds I through 4. At the fifth shot, pressure dropped and then continued to increase until, at the eighth shot, pressure, went to 82,120 psi; and the technician wisely stopped the test. The raw data was then used to prepare additional graphs (fig. 1) which show that, after ignition, pressures dropped momentarily to near zero on the graph before beginning to rise again.

To interpret this data we have to first understand the ground rules applicable to pressure testing with conformal transducers. The key term here is 'offset" which relates, primarily, to the specific cartridge and the brass used therein and must be determined for each transducer and lot of brass. The offset is the amount of pressure required to obturate the case to the chamber and begin to exert pressure upon the transducer. In this case the offset was 3,800 psi so when we look at the time/pressure curves produced in the test; we must understand that we are not actually seeing pressures below the level of the offset. There is a distinct dip in the curve, however, shortly after the pressure begins to rise when it drops to a level somewhere at or below the offset pressure. All we can say for sure is that, at this point, the pressure is <3,800 psi. Engineers calculated that for the specific bullet being used it would take pressure of at least 5,000 psi just to keep the bullet moving.

Hello Larry,
I had some of my reduced loads tested at a German ballistic laboratory and have seen no drop in pressure curves to speak of. It would be interesting if the article showed any traces of pressure over time. I have included one of my traces with a 303 Brit. load for comparision.

Regarding the low pressure observed on shot #5 I myself would not attach too much importance to it. From a statistical point of view the standard deviation of chamber pressure in reduced loads can be any thing from 850 to 2000 psi ( piezo measurements) In fact I had one trace with light 123 gr. jacket bullets combined with 27,0 gr. of VV N-110 were standard devation was a high as 5,000 psi while Vo. was a mere 53 fps. Normal standard devation of my loads were between 1,000 and 1,500 psi.

The particular trace sown refers to a load with a 174 gr. cast bullet with a reduced load of 29,0 gr. VV-N-140 where a case filler similar to Buffer Mix # 47 from Ballistic Products Inc. was used so that no empty space was left between powder and bullet. Buffer was slightly compressed to avoid any mixing of buffer and powder in transit. Average Vo. 1844fps SD 28fps. P-max. 25.450 psi Sd 1440 psi. Sorry the original document is in German.

Best regards,
Adrian, Germany.

P.S. Upload of traces didn't work the files are slightly too large about 120/123k. as jpg. Can't seem to get them smaller without losing too much detail/sharpness

[FirstBrit]

P.S. Upload of traces didn't work the files are slightly too large about 120/123k. as jpg. Can't seem to get them smaller without losing too much detail/sharpness

As the old saying goes .... If at first you don't succeed try, try again! Eureka!

Best regards,

Adrian, Germany.

http://castboolits.gunloads.com/imagehosting/thum_72184ec260dbe15a2.jpg (http://castboolits.gunloads.com/vbimghost.php?do=displayimg&imgid=2708)http://castboolits.gunloads.com/imagehosting/thum_72184ec25dbef396d.jpg (http://castboolits.gunloads.com/vbimghost.php?do=displayimg&imgid=2707)

[Larry Gibson]

Adrian

Yes there is a "trace" that shows the drop in psi in the article. I too am having trouble getting the article to upload both here and in an email to you.......working on it though.

There is indeed an ES to psi measurements just as there is to velocities since very few measurements of the same load are identical. There is also an accepted ES spread for any load by SAAMI. SEE potential with cast bullets is reduced considerably because of the plastic nature of lead alloys vs copper jackets. The lead alloy bullets simply will give way well before jacketed bullets if they get "stuck" in the bore while pressures are still quite low and still safe. It is the jacketed bullet that gets stuck in the throat that creates the "bore obstruction".

I have many times had pressure traces (M43 Oehler) with cast bullets that show a slight leveling of psi as the bullet moves out of the case and into the throat before the trace rises as the psi rises. The information derived and observed in the article test is quite reproduceable and is thus a more positive answer than the unproven theories that abound.

Larry Gibson

[390ish]

Wife talked to her professor today. She told him the entire Internet reloading community wanted to know if he was going to follow through. He said he has been busy and is trying to get in touch with one of the aforementioned forensic experts to take a look.

[uscra112]

I'm still interested, no matter HOW long it takes.

Phil

[uscra112]

Thank you Larry for reposting that article. There's still a mountain of Bravo Sierra being blathered about on this and other forae about SEE.

And ain't having the proper instrumentation WONDERFUL?

OTOH, as one of my long-ago bosses moaned about my new laser interferometer: "This thing tells us things we didn't know we didn't want to know".

[390ish]

So, the article posted by Larry explains SEE as when the primer generally launches the bullet down the barrel, bullet stops, and in the interim the burning powder creates a pressure so great that it bursts the action before there is any chance of the bullet moving forward?

I guess that makes sense to me. As I stated early in the thread, these loads had poor neck tension. I had expanded the brass with a 31 cal M-Die plug and had to go back and taper crimp the rounds into place. The 30 cal plug had wandered out of the M-Die drawer in my room when I was loading these rounds. That is a good article, even if I had read it four times for it to sink in.

[Larry Gibson]

uscra112

And ain't having the proper instrumentation WONDERFUL?

OTOH, as one of my long-ago bosses moaned about my new laser interferometer: "This thing tells us things we didn't know we didn't want to know".

Boy, isn't that the truth....I am constantly amazed at the "offense" taken when such instrumentation tells us some of our pet theories, myths and old wife's tales are wrong. Some people get down right irritated about such.......I would have thought we'd all be interested in the truth of such but that certainly isn't the case with some......[smilie=b:

Larry Gibson

[gandydancer]

I have used a ton of 5744 over the last 20 years or so in just about any caliber you can think of 32/20 win to 458 win to 50/140 sharps and never a hickup. I don't think your trouble is with 5744 powder. but what ever I'm glad your OK. GD