Thread: Pressure / barrel speeds?

Originally Posted by Gibo

Nasty

Had a beer or two after that one

Originally Posted by BRADS

Had a beer or two after that one

I bet. Good tip on the handloads given with sale. Pull em or chuck em

Originally Posted by Gibo

I bet. Good tip on the handloads given with sale. Pull em or chuck em

Take you don't want 90 22-250 loads?
Warmish lol

Originally Posted by BRADS

Ok when your brass does this
This wasn't my loading....it came with a gun I brought.....
Guy said they where all sweet, he seemed two no his stuff,
the first few where all fine
I really spat the dummy bolt lift was REALLY hard. I was glad it was in a Sako, a lesser action the results may have been a very different......
Lesson.....never use loads your given
Let's use this as a worse case example

That definitely is a good one in the pressure department, I bought a Remington 788 in 243 a few years ago it came with some reloads from a well known ammo re-loader the shop told me who made the ammo all good with me but he never said fire at your own risk. First and second shot was sweet third shot big orange flash in my face with a big bang, bullet tumbles down range and smacks side on into target. Look at rifle smoke coming out of places it should not be coming out of along with the odor of burnt oil, go to open bolt hello it is jammed solid took it to feller who made ammo, the feller hammers bolt open, extracts case with case firmly implanted into bolt, hammers case out of bolt face primer drops on ground with a huge tit where it extruded into firing pin hole, primer pocket almost doubled in size and all case head stamping was just a bright shiny surface and all stampings gone, needless to say rifle was going to take a fair bit to fix.

Originally Posted by Gibo

Ok guys im trying to get my head around a few things.

Firstly pressure. Why is it lighter pills in the same cal can use more of the same powder than heavier pills. Is it to do with resistance?
How can this effect the case differently (pressure wise) ?

Secondly barrel speed?? If someone has told me my barrel is slow (tikka) how could a magnum of same cal same (tikka) go any faster?

Just getting my head around the basics of reloading so keen to learn. Hope these even make sense: D

1-The lighter pill gives less resistance to the explosive charge trying to move it, the charge is able to expand into the increased space as the lighter projectile is driven out of it's (the gas) way faster than a heavy one - the heavier projectile has more inertia for the gas to overcome before it can drive the projectile down the bore to relieve pressure by creating space (volume), so if the heavier charge is the same as the light charge, pressure spikes faster because it has nowhere to go. When the resistance is too great, the pressure will find somewhere other than the bore to go, like back through the primer and bolt vent.

2-Two barrels from the same manufacturing run, in the same length, twist rate and calibre will not (near impossible in mass production ) be identical in bore dimension, as the projectile swages to the bore, so it is gripped and rotated, the tiniest, microscopic difference in the bore dimensions will change the resistance level to the projectile, the one with greater resistance will be the slower of the two.

So in order to build a "fast barrel" one would want the minimum possible land hight and width while still managing to turn the projectile?

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No one has mentioned type of rifling or projectile bearing surface?

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Originally Posted by R93

No one has mentioned type of rifling or projectile bearing surface?

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Do tell?

Originally Posted by Gibo

Do tell?

Someone will no the proper answer but this is my basic understanding.
Some of the longer double banded (Barnes pills?)create way more pressure than the same weight in other pills,
Has caught a few out

Originally Posted by BRADS

Someone will no the proper answer but this is my basic understanding.
Some of the longer double banded (Barnes pills?)create way more pressure than the same weight in other pills,
Has caught a few out

Other way mate likes of Barnes and gs custom projectiles with more grooves have less engraving pressure so can load higher go faster for same pressures.

Gmx have a couple in them and nosler etips have none hard projectile engraves hard and puts pressure back up.

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Originally Posted by tui_man2

Other way mate likes of Barnes and gs custom projectiles with more grooves have less engraving pressure so can load higher go faster for same pressures.

Gmx have a couple in them and nosler etips have none hard projectile engraves hard and puts pressure back up.

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Thanks Abe that does make sense.

Here's a few pictures and details of what was bad. There was some good from this one though.................. the chamber didn't explode in my face! This had very, very high pressure.

This was/still is a 223 MAX in Remington Model 700 - 60gr Partition doing 3640fps in a 1:12 twist factory barrel. The chamber has been reamed deeper to allow the extra length and powder capacity. 31.5gr of 2206H (my current safe load is 30.5gr giving 3420fps)

This photo show the ejector pin mark(the half moon or simile mark) on the side of the base. this is from when the brass flows so much that the pressure is enough to push the ejector pin back into the bolt. Sometime this can just look like a polished half circle in the base.
Also in this picture the primmer pocket has expanded so much that the primmer fell out. Lastly you can see scratches on the case; these are from the case has expanded so much that any tooling marks from the chamber reamer has allowed the brass to fill the marks and therefore mark the case very, very hard to extract. Again, this is a pretty extreme case of high pressure.


This one shows how much of the case is out of the chamber. This is not meant to be a belted case.

Shit! Thanks for that

Backed off half a grain and called it good?

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Originally Posted by veitnamcam

Backed off half a grain and called it good?

That's what I did to start with, shot a deer and then the bolt still would open that easy. Just as will the stag went down straight away!

Backed off another half grain after that.