Detonation in LIGHT Loads

[Kragman71]

When I started out handloading ammunition,years ago,I had quite a few underpowered rounds that failed to exit the barrel.
It was a good thing,because,now,I check the bore when ever I cannot find the bullethole,and something feels"different" when I fire a round.
I believe that it is just good policy to do this.
Frank

[slipup]

Has anyone had any success in getting better accuracy tuning the "bullet jump" on 223 handy rifles.  Best accuracy, for me, has been 7/8" using 50gr sierra over 27gr Varget.  good results with N133@23 gr under 50Vmax. doing 1".  i think the gun can do better since i found a bullet that will stretch to the lands, but was wondering if any of you experts have found the sweet spot to beat the freebore/bullet jump. 

[opatriot]

GDAY FRIENDS ... Well this is a funny thing .... i was just about to load up some reduced loads for my marlin 45-70 and had some time to kill so i thought i would flip through some posts ... and now im scared to death .. !!   I have the lyman#47 edition and they have two loads listed i was going to make up . . the 1st was .. 405gr jack/sp with unique .. 11gr start up to 15gr max .... the 2nd was 400gr cast with 13gr start up to 16gr max ... they list all the loads that they used fillers with and these two loads they " didnt " use fillers with ........ sooooo what do guys think ??  should i go ahead and work up some loads or is it a bad idea  ?               kind regards ........... Davey

[John Traveler]

The American Rifle technical advisor stopped recommending the use of dacron "kapok" fibre space fillers several years ago.  Previously, they advocated reduced and cast bullet loads using the space filler.  The stated reason is there have been many incidents of chamber "ringing" and throat damage from using such loads.  This type of damage has also been extensively reported in Rifle Magazine.  The problem is most common in large (.38-55, .45-70, etc straightwall calibers.  The melted dacron can apparently form a bore/chamber obstruction.

What some black powder cartridge rifle (BPCR) reloaders do is use Cream of Wheat cereal to fill the space, or use pastboard wads, or both, to obtain the proper black powder compression.  The same thing is done with equivalent smokeless loads.  Cotton fluff from medical grade cotton is also used.  These are considered to present much less risk to the gun chamber.

The Lyman loading manual you quote is over 35 years old.  The test data is likely a bit out of date.
Unique is favored for reduced-up-to-standard velocity loads for LEAD bullets in the .45-70.I do not use those reduced loads of Unique for 405 grain jacketed bullet loads.  There are more suitable powders available.

[Dave in WV]

I read a piece written by a retired US Army engineer that had worked at Aberdeen Proving Grounds, MD. He said the Army has known about detonation for years and had reproduced it. It occurs when the ignition from the primer can flash over the whole length of the powder column.

[opatriot]

GDAY ... THANX For your comments ........... i think ill do a little more research before loading my 45-70 with pistol powders ..... as far as cream of wheat fillers go ... has there been any complications with its use ... ??  and the same question for cotton .... ?? i wouldnt have a problem loading with fillers because its a slow process anthoo .....was wondering what the difference is between surgical cotton and the cotton balls from the drug store though ... ??     kind regards .... Davey

[Graybeard]

Detonation in cartridges is an unproven theory to explain why from time to time for no particularly apparent reason guns go BOOM rather than bang. Many have tried to duplicate it with all sorts of lab experiments and so far have failed miserably. It supposedly happens when you use light charges of slow burning powder not with small book listed loads of fast burning powders.

Unique is considered a fast burning powder and that is why it is widely recommended for light loads in fairly large cases. The smart thing to do is to ALWAYS use book loads and always use them as listed in the book. Don't play around and experiment by changing up a bunch of things to see if you can work up your own load just follow the book receipes. Load no lighter or heavier than the books recommend and most of the time you should be on safe ground.

Some few folks claim to KNOW beyond all shadow of a doubt they had a detonation or know someone who did but todate absolutely no one anywhere has come forth and produced documented evidence that they can duplicate the conditon and specify a load that did it. I remain of the opinion that either there was a barrel obstruction not noted or a double charge or maybe even both that created the detonations but like the theory of detonation that's merely a theory on my part. Far too much is made of this and most likely it creates more dangerous situations than it cures as a result.

Just follow pressure tested book loads and you should be just fine.

[opatriot]

Thanx graybeard ... for the advice ....I will stick to the book .. i think i will just load up a few without the filler like whats listed in lymans book and then check the bore after the first few tryal shots to make shure its clear ..........kind regards ............davey .......... oh and graybeard i agree ... Jesus is the way ...................

[calvon]

Back in 2002 Charles E. Petty had an excellent article on this in Handloader Magazine #187. I no longer have the magazine but I did scan the four pages that he wrote. These four pages are in jpeg format and the aggregate size of them is 2.5 MB. If you have enough bandwidth for this, let me know and I'll email them to you. It is a very revealing story that lays a lot of old wives' tales to rest.

calvon@bendbroadband.com

[beemanbeme]

As posted, I don't think the phenomenon has ever been replicated in a laboratory or a controlled situation.  IMO, I think it goes along with many of the "bullet failures" we read about.  Might even have to put it in there with those bullets that shoot 2" groups at 100 yards and then turn a corner and shoot 1" groups at 200 yards. 
If it sez they're okay in a current book, they should be okay.  Remember, info you get from someone in cyberspace may or may not be good. The person giving it has no liability at all. 

[coyotejoe]

Well Steve, it happened to me. I was loading a listed starting load of Winchester 760 in a neck-sized once fired 3006 with a 165 grain bullet seated as far out in the case as I could. The first round was a bit soft but I expected less than maximum recoil with a starting load. The bullet hit the target jut about dead center - next shot went puff.......   and then BOOM. The case was badly deformed with the head extruded to larger than normal, case body was bulged and the primer pocket was so big the primer was destroyed. After recovering from the shot I checked my gun and it seemed unharmed but I packed up and went to the gunsmith to have everything checked out. The weapon was fine - a Remington made 03A3 - and the only explaination was a "delayed detonation" from powder that was ignited poorly over a large surface area. In using low powder densities I always put the bullet to the OAL specified in the book.

PaulS

  Well I've told this story before but this seems a good time to tell it again. I was loading for a Winchester M-100 auto in .308 with 150 grain bullets and the only suitable powder I had was Hodgdon's H-414, same as Winchester 760. That is not an entirely suitable powder for 150 grain bullets in the .308 since 50 grains is all you can get in the case and my Lyman #47 manual lists that as producing only 37,500 CUP, well below standard operating pressure for the .308. I first loaded five rounds each with 47, 48, 49 and 50 grains. Fired all of those and pressures did seem very mild just as the Lyman book had predicted. I got the best group with 48 grains so I loaded the same 20 cases all with 48 grains and returned to the range within an hour. I was shooting prone and on the eighth shot I thought something sounded odd and thought I had caught a puff of smoke in my peripheral vision. I glanced to the right where the semi-auto was tossing brass and there was one case with a gaping black hole where the primer should have been. The case head was grossly distorted but the rifle was OK.
 Now when I tell this tale people want to explain it away. "Too much powder", no, the case won't hold enough of that powder to produce even normal pressure, no way you can overload with H-414 behind a 150 grain .308. "The wrong powder", no, I dropped all loads from the same powder measure, how could one case out of forty get the wrong powder. "soft case head", no, that case had been previously loaded with a similar or heavier load and the primer pocket was still tight. "Deep seated bullet", well it was a semi-auto rifle but it was also a compressed powder charge, not likely that the bullet could have been driven much deeper into the case in feeding.
  I do understand why people are reluctant to believe anything could go wrong with a load listed in a good manual but in this case it sure did. Normally that load would have produced only about 30,000 CUP and I believe that is borderline minimum pressure for H-414 or W-760 powders to burn properly and S.E.E. seems the likely explanation. Years later I had a similar experience with what should have been a mild load of H-414 in a Remington M-600 .243. It has been said that investigations have always concluded "reloader error". The truth is that very few of such incidents are ever "investigated" at all and if they do investigate and come up with no conclusion at all, then "reloader error" is the quick and easy answer. Don't believe it if you don't want to but I'm certain it can happen. We just don't know so much about how smokeles powder actually behaves as we may wish we knew.

[beemanbeme]

Well, I'm not a physicist nor a ballistician and I just can't get my mind around it.  Rifle powder is energy.  You ignite it and it gives up that energy.  In a confined space, as the powder burns, the pressure goes up and the powder burns faster and the pressure goes up and the powder burns faster.  You reduce the powder or increase the space and the pressure has to be less.  I think the original problem with reduced loads were hang fires, delayed fires, and bullets that failed to exit with a second round fired behind them.  It was easier to blame it on some sort of voodoo than say "I screwed up."

[coyotejoe]

Well sir, you have just restated the standard theory of smokeless powder, that is how it is supposed to work, in theory.In fact no one really knows what happens inside a firearm. The theory seems to work 99.999% of the time. But there are those instances which do crop up from time to time. The energy content of the powder is one thing and their rate of energy release is another. That is why we have so many propellants on the market, each having a rather narrow range of application, to obtain the proper rate of energy release. The difference between a detonation and a controlled burn is a matter of milliseconds. I look at it this way, all smokeless propellants are basically a high explosive which has been chemically and physically altered to behave as a propellant. If you were to extract the nitroglycerin content from a double based smokeless powder and load one drop of pure nitro into a cartridge, in that confined space it would surely wreck the firearm.  Whenever we touch off a load of smokeless powder we are basically hitching a race horse to a plow and hoping we reach the end of the row before the horse gets to going too fast.  All generally goes well, but then there is the time a hornet stings the horse in the butt!