New Pressure trace discussion.......

[Richard]

Can't afford the bars and carousing with all I spend on bullets an powder Chuck ;D
Richard

[ET]

Richard

What I find interesting is comparing secondary spikes between using a sabot and sabotless. It appears that with sabotless the secondary spikes, if any are less intense in the duplex and triplex loads. I know this is an early small sampling but may be worth keeping an eye on with more sampling.
If this condition holds true it would be interesting to try and find out why.


Ed

[pposey]

I would say there is slightly more resistance with a sabotless load, correct??

[rossman40]

This is probly the most intense study since the earlier round of pressure trace testing RB and others did. And it is in .45! I doubt if any of the powder companies or Savage have gone this far.

If there was a Noble prize for muzzleloading research Richard would be the winner this year.

Now if we can get those that have a PT unit to collaborate and crosscheck that would be the berries.

[jeremylong]

Yup - kick butt stuff guys.

[Richard]

No Nobel prizes!! This was Jon's idea and his $$$ to provide the equipment. I just get to try and figure it out ;D. Edge provided me with a One Shot trace with a 300 gr. sabot less bullet and 55 gr. of N-120. I will try to duplicate it Tuesday and we can compare notes
Richard

[pposey]

That will be great, course could how tight the bullet fits effect pressure?

[Richard]

I am sure it will, but not as much as you would think? I have had some sabot less loads I shot go down very tight and others not so tight and the velocity difference was really not that great. I usually try to guess, before I pull the trigger, if a tight load will have a much higher velocity than my previous loose load? Many times it is only a matter of maybe 20 or 25 fps difference? I just think sabot less is so much more a PIA than saboted. The sizing is so critical and I think spring back occurs as these sized bullets sit in the box for a couple of weeks . Maybe with solid copper's this does not occur........so I have heard? Just so much simpler to shoot saboted bullets But it is fun playing ;D
Richard

[spoonover]

Would a short barrel show the same (second spike) readings? If the projectile (close to the end of the barrel) gets extra speed from the second spike in pressure, how much can it be?

22LR's are at there most accurate in a 5 to 7" barrels. The last spike might be the same effect on your 45 pacnor giving added FPS and accuracy to boot?

Could a short barrel eliminate the need for second PT instrument and lap top for this second strain gauge? What I am trying to say, if a loss of greater than 50 feet per inch of barrel length there could be second spike!

Maybe get one of the bulged barrels and get some use out of it, that could be priceless?

[hubcap52]

I'm interested in getting this trace system. how long do the gages last?

[pposey]

If you go too short you start having problems burning enough powder, at 21 inches I could not effeciently use more than 54 grains 4198 in my .45 pacnor

[ET]

Dec 25, 2010 0:28:25 GMT -5 hubcap52 said:

I'm interested in getting this trace system. how long do the gages last?

Hubcap52

From what I understand the life of a strain gauge is dependant on abuse and the integrity of the glue holding the strain gauge. Sitting below the scope does offer it some shelter from abuse but doesn’t protect it from heat that can affect the bond of the glue. So if the barrel is allowed to heat up to high from quick repetitive shooting it appears the integrity of the glue bond would be affected.

A method incorporated into the unit to monitor the gauge repetitive accuracy is called “Verification Data”. By using a specific load measurement over time you can monitor the gauges response and if it begins to show lower pressure readings that would be an indication that the gauge is not functioning properly.

See insert below from manual referencing this Verification Data feature.



I like thinking this feature is a sort of built in lie detector test for the strain gauge. ;D



Ed