Thread: Remington 700 Sako and M16 extractor conversions

So running along the safe pressure/velocity theme whats the general opinion on quickload?

Originally Posted by Greg Duley

Hell no, you load to the same velocity, then you'll be getting the same pressure as the loading manual load. I wrote an extensive reloading series on this back a few issues. You may take more or less powder to equal the same velocity and pressure, depending on your individual rifle's chamber and barrel specs. The velocity is your best guide to pressure if you don't have pressure testing equipment. Just be sure you're comparing like with like, eg same barrel length - minor chamber dimension variations don't matter.

So if you swap out a barrel, with the same chamber specs, and need 4 more grains to acheive the same speed with all variables being equal, are you saying that chamber pressure is the same on both?

Originally Posted by veitnamcam

True but then how tight/rough/smooth was the test barrel? how accurate is your crony? how accurate was thiers? how well calibrated was their pressure test gear? and you can guarantee you are using different components to the test data so its a moot point really.
Let common sense prevail (even if its not that common)

Again I can see where you're coming from- but as you've just pointed out: that's even more variables that can lead things to things going astray.

-Common sense is a great cure for most problems (Just don't try telling a girlfriend that in the middle of an argument- I did, didn't work out well for me).
And I'm certainly not disagreeing with the fact that within normal scenarios most reloaders will be absolutley fine with the "load up till you get the same velocity" approach.

-What I'm disagreeing with is the statement that: same velocity = same pressure. Cos it's not correct.

Originally Posted by Spanners

So if you swap out a barrel, with the same chamber specs, and need 4 more grains to acheive the same speed with all variables being equal, are you saying that chamber pressure is the same on both?

That's what I was getting at Spanners. Physically speaking it just isn't possible.

No ones claiming exact same pressures are they? They'll be roughly close enough to be indicative. Anyone done the actual pressure testing to dispute this?

It’s a general guideline. The basic premise is that load data pressure barrels have minimum spec’d chambers and bores. And all factory barrels are at the looser end of the specs, some looser than others. If you match the test barrels velocity in the factory barrel you will have slightly less pressure. If the data was developed in a looser spec’d factory barrel and you match it, you’ll have about the same pressure. Obviously the same barrel length and components etc is a given. The only time you could get into trouble here is if you have a faulty barrel with a constriction or such a rough surface you’re tearing up jackets. We’ve never seen a barrel this bad, but have heard of the odd one, Davey Hughes 300 Blaster a case in point, not that exhibited particularly elevated pressures by the sound of it.
Even matching the velocity with a tight bore Lilja to a loose bore Broughton, you won’t get into trouble unless you were over the top in the Broughton in the first place. We have pressure tested this exact scenario many times.
Anyway, as Vietnamcam and others have said, if you exercise common sense and watch for the usual pressure signs, matching the velocity is the best way to match the maximum load in a loading manual unless you have access to pressure testing gear.

Spanners, if you replace barrels and need 4 grains more powder to match the velocity, everything is certainly not equal! Something is hugely different between the two. Depending on the size of the chambering you’re talking about, there would be a huge pressure difference in something like a 223, but not so much in something like Cheytac at the other end of the spectrum.

300 RUM, Factory SF2 barrels, both headspaced within 2 thou to each other, running fireformed and neck sized only brass.
Same ammo loaded on same day in same session for same component lots, fired over same chrony 2 days apart = 200 fps loss int he new barrel and 4gr required to get it back. Another chrony was used to check the -200 as it was not to be expected.
The difference between the 2 barrels was thread on the end - one metric, the other UNF - they had both had approx the same number of rds through them ~180 each, throats and bores looked identical through bore scope.
Fired cases fit either chamber, and a chamber cast confirms they are to the same spec less the 2 thou headspace
The +4gr load shows alot more pressure on the primer. The prior load showed next to no pressure on the primer - no way in hell would I shoot he +4 i the orginal barrel - would be hospital time.
The +4 load showed no soot at all on the neck, where the original had a wee bit 1/2 way down.
Given the primer signs, the fact the neck is sealing better, while disregarding knowing the load is +4gr heavier (~4%), and ignoring the simple physics of 'more bang bang in a sealed container', its obvious the pressure has increased.

The barrel is plain slow.. its shoots like a demon, but its dead slow.
A statement that adding powder till you get the same velocity, will give you the same pressure; is simply wrong

I wish it was true as I have an AR barrel which is super slow and at its pressure limits, where its twin has the speed I'm missing with no issues.
Maybe it was chambered from the wrong end?

Interesting, I'd love to hook our pressure gear up and have good look at those two barrels. There has to be some major differences in chamber or bore. Have you slugged the barrel? That will often show up constrictions and other bore variations. Bring them down some time if you would like to, and we'll stick strain gauges on them and check them out.

Anyway, this is the exception that proves the rule, and doesn't mean a reliable chronograph isn't your best tool for general load development working up to loading manual maximums. I have well and truly qualified this in the post above.

Even more interesting is that the Mfg of the pressure testing system was taken to task a couple of years ago on Acc Reloading and was completely unable to describe how his equipment could give a pressure reading for any given barrel - so perhaps take any information gained from one with a grain of salt! They can certainly show you a trend, but as for a reading in "that chamber" vs "another chamber" apparently not.

Originally Posted by Cyclist

Even more interesting is that the Mfg of the pressure testing system was taken to task a couple of years ago on Acc Reloading and was completely unable to describe how his equipment could give a pressure reading for any given barrel - so perhaps take any information gained from one with a grain of salt! They can certainly show you a trend, but as for a reading in "that chamber" vs "another chamber" apparently not.

I alluded to that above or maybe it was another thread but as per pressure testing,How can you truly calibrate a barrel and chamber?
You cant really.
You could thread and cap both ends and hydraulic test and calibrate the strain gauge but you would have to destroy a action to seal the camber end with the action attached?
Then this calibration would only be valid for that chamber/barrel/action.
No doubting its a lot better than looking at primers but I would put money on two different people with the same pressure test gear and the same rifle and same load but using there own measurements and stain gauge placement getting different numbers.

Agreed Cyclist.
Chamber diameter, barrel diameter, barrel material will all change these figures
The same chamber cut in a Chromoly barrel and a stainless, of equal external diameter, fired with the same load is going to indicate different pressures
The position of the sensor is going to change values as the hoop and radial stresses measured for the neck will be vastly different to the shoulder or case head.

This is no different form a DIY dyno - it will give you an idea on which direction you are heading, but you cant turn around and say that this number is it nor be even close IMO

Hell - Saami and CIP cant even get close to agreeing with each other, let alone a backyarders

Given brass yield of ~220 MPa (approx 32000psi) I would give their deformation and reading of as a pretty good gauge of pressure - after all they are all the same diameter, so its apples and apples regardless of case size
Copper cup primers ~100 Mpa - 14500psi..

You guys really do crack me up. The Oehler Ballistics laboratory is used by a lot of the bullet manufacturers ballistics labs to develop their loading manuals. I spent quite some time with the guys in the Nosler lab learning all the tricks of the trade.
Yes Spanners, most of the things you mention do matter, which is why it has different inputs for all of them, including the type of steel and its Rockwell hardness rating. You do not place the strain gauge randomly, it must be situated in a precise, repeatable spot over the case body.
As brass varies so very much in composition and hardness between brands, I find it amusing that you think this is a more reliable way of establishing. pressures. As for primers, there are again many variables between brands, and between how different rifles exhibit pressure signs on the primer.

Well we are getting pretty far from the original topic (which I dont believe that anybody actually disagrees with - this extractor that extractor = meh)

I also dont believe that any of the thoughtful reloaders on here believe that looking at a primer can give you any real information, perhaps measuring case webs is better but nothing a reloader can do can tell you what pressure they have reached.

Are we any worse off than the big boys though?

Copper units of pressure, lets all drill a hole in our chambers + its wildly inaccurate - MINT. Piezo transducer - similar problem.

Strain gauge compares deformation of the chamber area of your barrel during the shot to the deformation produced by a "reference load" - now if you can provide me with an actual real live "reference load" which you are using to calibrate your instrument then I will gladly swap one for as much rocking horse shit as you can carry away with some pixie dust to lighten the load. Why are strain gauge pressure figures never published I wonder? Yes its a tool they will use because it shows a trend nicely, but go on then = explain to me how this actually measures pressure inside a chamber and explain how that chamber can be compared to another in the absence of a calibrated load. (crickets chirping etc)

I will try to dig up the thread later, but the Strain guage dude was left with his dick in his hand (I will resist saying it was Ken Oehler till I find the thread, but im pretty sure it is him)

Originally Posted by Cyclist

Well we are getting pretty far from the original topic (which I dont believe that anybody actually disagrees with - this extractor that extractor = meh)

I also dont believe that any of the thoughtful reloaders on here believe that looking at a primer can give you any real information, perhaps measuring case webs is better but nothing a reloader can do can tell you what pressure they have reached.

Are we any worse off than the big boys though?

Copper units of pressure, lets all drill a hole in our chambers + its wildly inaccurate - MINT. Piezo transducer - similar problem.

Strain gauge compares deformation of the chamber area of your barrel during the shot to the deformation produced by a "reference load" - now if you can provide me with an actual real live "reference load" which you are using to calibrate your instrument then I will gladly swap one for as much rocking horse shit as you can carry away with some pixie dust to lighten the load. Why are strain gauge pressure figures never published I wonder? Yes its a tool they will use because it shows a trend nicely, but go on then = explain to me how this actually measures pressure inside a chamber and explain how that chamber can be compared to another in the absence of a calibrated load. (crickets chirping etc)

I will try to dig up the thread later, but the Strain guage dude was left with his dick in his hand (I will resist saying it was Ken Oehler till I find the thread, but im pretty sure it is him)

I would like to see this thread

Originally Posted by gimp

I would like to see this thread

+1


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