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Further proof that "she ain't blowed up yet" is not a sign of safe loading practices. Amen. Ands thanx for the information Charlie. BMT
"The Church can and should help modern society by tirelessly insisting that the work of women in the home be recognized and respected by all in its irreplaceable value." Apostolic Exhortation On The Family, Pope John Paul II
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The gasses are rich in hydrogen, and hot enough to glow. When they hit the air, they re-ignite... BANG! Secondary spike.
Interesting. Not sure how pressure could build to the levels Charlie describes after the hot gasses are vented to the atmosphere (either vented by a muzzle break port(s) or the bullet leaving the barrel) Charlie, what is the elapsed time between the secondary pressure spike and the moment the bullet leaves the barrel? Is this time similar on all the pressure spikes? I assume it happens on barrels with and without muzzle breaks.
HogWild
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Not sure how pressure could build to the levels Charlie describes That's one of the big questions, isn't it? I see the same spikes, and wonder the same thing. One thing about them: They have a fast risetime. They may even be faster than the amplifiers in the PressureTrace can track. I know of one product that attributes those spikes to barrel vibrations, and suppresses them.
Be not weary in well doing.
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Very interesting info. Sounds like heavy bullets at moderate velocities are the safe ticket...oddly enough, they seem to be highly effective on game too.
A question, which may only reflect extreme ignorance...
Have you seen any difference in secondary spikes related to the presence or absence of bullet crimp?
Thanks for sharing your findings with us.
"The more you run over a dead cat, the flatter it gets."
"If you're asking me something technical, you may be looking for My Other Brother Darrell."
"It ain't foot-pounds that kills stuff -- it's broken body parts."
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Could it be possible that oxygen is being "sucked" in through the ports, after the bullet passes, and re-igniteing the powder from the hot bullet? Virgil B. <img src="/ubbthreads/images/graemlins/confused.gif" alt="" />
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Hogwild
The pressure curve follows right with the bullet as best my equipment can tell. Several loads show the bullet exiting the barrel in the 25000 to 65000 psi range.
Muzzle brakes dont seem to have any bearing one way or another.
Charlie
The data and opinions contained in these posts are the results of experiences with my equipment. NO CONCLUSIONS SHOULD BE DRAWN FROM ANY DATA PRESENTED, DO NOT, UNDER ANY CIRCUMSTANCES, ATTEMPT TO REPLICATE THESE RESULTSj
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Denton
You are right, those secondary spikes come up fast. And some folks say the spike rises even faster than the gage can read......thats pretty darn fast....
Charlie
The data and opinions contained in these posts are the results of experiences with my equipment. NO CONCLUSIONS SHOULD BE DRAWN FROM ANY DATA PRESENTED, DO NOT, UNDER ANY CIRCUMSTANCES, ATTEMPT TO REPLICATE THESE RESULTSj
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muledeer Crimping seems to have no affect on the secondary spike. It can make a huge difference on the first curve on some loads. Loads that have either a weak primer(not hardly hot enough for that particular load) or neck tension that varies, will have what looks like a "squiggly" <img src="/ubbthreads/images/graemlins/grin.gif" alt="" /> line through the curve instead of a "smooth" curve. Crimping will many times remove the "squiggly". Amother way is to resize the brass without an expander ball. Seems like with the proper weight bullet, the pressure will even out at about 9000 psi for the last 8 inches or so of barrel and the muzzle pressure will be so close its hard to tell one shot from another. Seems these loads shoot well and have very low deviation in pressure , velocity, and point-of-impact. Several times I have saw a rifle shoot(say the proper load was from 45 to 50 grains of X powder) 45 to 50 with almost no change in group size. Even tried several times mixing up loads in a group, say one or two with 45 then a few with 49, and still groups well. Seems most of the time you can mix bullets of the same weight with the right powder in a group and cant tell the difference. I'll say it before anyone else can, "that sounds like bulls#!t to me" <img src="/ubbthreads/images/graemlins/shocked.gif" alt="" />, sounds like it to me too but I've done it several times. Whitetail saw that some with his 358 when he was here. The more I learn about this stuff the more confused I get... <img src="/ubbthreads/images/graemlins/crazy.gif" alt="" /> Charlie
The data and opinions contained in these posts are the results of experiences with my equipment. NO CONCLUSIONS SHOULD BE DRAWN FROM ANY DATA PRESENTED, DO NOT, UNDER ANY CIRCUMSTANCES, ATTEMPT TO REPLICATE THESE RESULTSj
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It would be interesting to see what the effect of chopping off 1/2" increments of the barrel would be on the secondary spike. If this spike is a factor of barrel length then the secondary spike would begin to subside after a certain amount of the barrel had been bobbed. No?
This is extremely interesting, Charlie. We are fortunate that you are willing to share your data with us.
Dan
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Wizard
I have already performed this test..... ....the hard way.... .....I blew the end off a # 5 338 Win mag barrel. After the barrel was recrowned, it was shorter than where the spike started when at the previous length and disapeared all together.
Charlie
The data and opinions contained in these posts are the results of experiences with my equipment. NO CONCLUSIONS SHOULD BE DRAWN FROM ANY DATA PRESENTED, DO NOT, UNDER ANY CIRCUMSTANCES, ATTEMPT TO REPLICATE THESE RESULTSj
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Thanks Charlie. I had wondered if you checked for the presence of the secondary spike after the barrel had been shortened. Forgive me if I overlooked that information earlier.
This whole matter is certainly interesting to ponder...
Dan
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Campfire 'Bwana
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Mr. Sisk - just a wierd question - do you think you could "move" the spike up and down the tube with a BOSS type of attachment?
I thought I had read somewhere that the 2nd spike may be a side effect of barrel vibration. Doesn't seem to be to me - I still think it is a powder burn rate vs neck tension vs voodoo.
Me
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Teal325 I wish you hadn't ask that question... <img src="/ubbthreads/images/graemlins/shocked.gif" alt="" />.....now you've got me to thinking.... <img src="/ubbthreads/images/graemlins/crazy.gif" alt="" />...dangerous thing, that thinking is.......more test...... <img src="/ubbthreads/images/graemlins/ooo.gif" alt="" />.....I'll need to live to be 140 to be able to do all these... <img src="/ubbthreads/images/graemlins/grin.gif" alt="" /> Charlie
The data and opinions contained in these posts are the results of experiences with my equipment. NO CONCLUSIONS SHOULD BE DRAWN FROM ANY DATA PRESENTED, DO NOT, UNDER ANY CIRCUMSTANCES, ATTEMPT TO REPLICATE THESE RESULTSj
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What I have learned so far is that using a powder that completely fills the case doesn't seem to be the best idea. The powder manufacturers say to always use a powder that completely fills the case....why ?????? because they are in business to sell powder.... Now, I'm not sure that this is true of the powder makers but I was posting on another topic and found something interesting on a powder manufacturers site. Special note: The MAGPRO was developed to suit ALL of the Short magnums calibers, from both Winchester and Remington.
It�s a slow burning powder, which fills the case well in the .30 bore short magnum variants. As a result the loads will be compressed.
In the case of the short magnum designs, this compression is not bad, since the there is a lot of �unseen space� around the base/shank .
of the bullet, which protrudes deep into the case.
The loading density, will gradually improve with the smaller bore diameters i.e. 7mm and .270�.
The greatest mystery in life is who we really are.
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Campfire 'Bwana
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I am here to help!! <img src="/ubbthreads/images/graemlins/grin.gif" alt="" /> Few more variables - floated barrel or not? preassure tip on the forend of the stock? How much tip pressure? Bed the first coupla inches of the barrel? How about a tight vs "normal" chamber? Primer variations vs ignition of the powder column ? Possible variations in the level of lapping in the barrel - as in a hand lapped vs basic normal rough barrel? Moly barrel and or bullets? Need any more I 'm here all week, try the veal and don't forget to tip the waitress. <img src="/ubbthreads/images/graemlins/grin.gif" alt="" /> I wonder if there are too many variables to nail this little problem down - don't forget atmospheric preasure!!
Me
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Campfire 'Bwana
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Charlie - if you are still lurking - any updates to this? I realize it's 5 years old.... 
Me
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Wow, I thought Charlie was back posting again... Damn.
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Campfire 'Bwana
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He last posted in 10/11 of 2009 - he's around some. Not nearly as much as he used to be though.
Me
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Wow, I thought Charlie was back posting again... Damn. What he said !!!
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