QB79 vs Temp n questions

QB79 vs Temp n questions

Joined: June 2nd, 2002, 10:34 pm

October 18th, 2010, 7:31 am #1

<p>I've been setting up a 79 for myself, I posted about the power adjuster down the page, and ran a temp/vel graph.</p><p><img alt="QB79_fps_temp_jpg_2010.jpg" src="http://www.network54.com/Realm/tmp/1287389425.JPG"> 
The odd thing is that it max'ed at 22, I know that 22/72 Deg is recommended as the temp to test at but I wasn't expecting the max vel to be there.

Any idea why? There isn't much left that is standard, 3.5oz bottle, light hammer, new ptfe valve stem/seal, longer soft valve spring, transfer port, long probe and short barrel.

So I'm thinking if the ambient temo is bellow 15 deg C the power drop is too extreme for anything but plinking.


ATB Ora


My Website -http://www.ora8i.rivington-riflemen.org
</p>
Last edited by ora8i on October 18th, 2010, 8:10 am, edited 1 time in total.
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Joined: March 3rd, 2005, 1:38 pm

October 18th, 2010, 12:04 pm #2

Your velocity increase follows the pressure increase until you reach your peak velocity at 22C, it then looks like the increase in pressure isn't letting the valve to open fully after that temp......have to put a stronger spring behind the striker maybe but then your even velocity will suffer....

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Joined: June 7th, 2010, 12:14 am

October 18th, 2010, 12:23 pm #3

<p>I've been setting up a 79 for myself, I posted about the power adjuster down the page, and ran a temp/vel graph.</p><p><img alt="QB79_fps_temp_jpg_2010.jpg" src="http://www.network54.com/Realm/tmp/1287389425.JPG"> 
The odd thing is that it max'ed at 22, I know that 22/72 Deg is recommended as the temp to test at but I wasn't expecting the max vel to be there.

Any idea why? There isn't much left that is standard, 3.5oz bottle, light hammer, new ptfe valve stem/seal, longer soft valve spring, transfer port, long probe and short barrel.

So I'm thinking if the ambient temo is bellow 15 deg C the power drop is too extreme for anything but plinking.


ATB Ora


My Website -http://www.ora8i.rivington-riflemen.org
</p>
Did you observe the shot to shot variation over a 10 shot string at each temp?

That number may be over ten fps. Perhaps your plot data is already and average.

thinking out loud
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Joined: March 28th, 2002, 6:54 pm

October 18th, 2010, 4:18 pm #4

<p>I've been setting up a 79 for myself, I posted about the power adjuster down the page, and ran a temp/vel graph.</p><p><img alt="QB79_fps_temp_jpg_2010.jpg" src="http://www.network54.com/Realm/tmp/1287389425.JPG"> 
The odd thing is that it max'ed at 22, I know that 22/72 Deg is recommended as the temp to test at but I wasn't expecting the max vel to be there.

Any idea why? There isn't much left that is standard, 3.5oz bottle, light hammer, new ptfe valve stem/seal, longer soft valve spring, transfer port, long probe and short barrel.

So I'm thinking if the ambient temo is bellow 15 deg C the power drop is too extreme for anything but plinking.


ATB Ora


My Website -http://www.ora8i.rivington-riflemen.org
</p>
Since you want to keep power under your limit, that looks like a very useful tune.
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Joined: June 2nd, 2002, 10:34 pm

October 18th, 2010, 5:12 pm #5

I'm happy with it, as you said Scott I've got to stay under 12 so it's looking good.

I've been very fortunate with this one, the power adjuster was nearly perfect first time I only needed to make one adjustment to the back block and the temp/vel relationship is just about perfect.



ATB Ora

My Website -http://www.ora8i.rivington-riflemen.org
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