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Assuming you measured at about the same point on the barrel I would have expected the temperatures to be closer together. <font color="blue">That's good. I too would have thought they would have been closer together </font>
With a 7mmWby mag I burn almost exactly the same amount of powder as you do. My barrel would be a lot hotter than that . <font color="blue">In the summer my bbl, Rem 700 sporter blue bbl would have been too hot to touch. </font>
There are two questions at hand.
Why did heat production drop so dramatically between shots for 4350? <font color="blue">That's what we'er shootin' for!! Pun </font>
Another couple of shots and there would have been no increase. <font color="blue">I wondered about that when recording it but took extra precautions to ensure that I measured what I measured. Will shoot some more. </font>
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Thanks for the observations. Helps one to get through his own stinkin' thinkin'. [img]/ubbthreads/images/graemlins/blush.gif[/img] [img]/ubbthreads/images/graemlins/blush.gif[/img]
Guess I should improve my test setup a bit and do some more shootin' [img]/ubbthreads/images/graemlins/frown.gif[/img] [img]/ubbthreads/images/graemlins/grin.gif[/img]
The test set up: Cut neck off of 222 Rem. Filled w/J-B Weld Kwik set. Placed this fancy little test device on top of the bbl right at the white spacer behind the fore arm cap.
Just prior to the JB Weld hardening, I pressed wife's pyrex digital thermometer in to make an indent w/the bottom close to the bbl. [Fat chance of finding a thermocouple in southeast Idaho [img]/ubbthreads/images/graemlins/crazy.gif[/img] - Could have found one out at the Idaho National Laboratory, but since 9/11 the rules of engagement have changed and my badge ran out Tuesday [img]/ubbthreads/images/graemlins/grin.gif[/img] [img]/ubbthreads/images/graemlins/grin.gif[/img]]
With that gizmo on top of the bbl, it is easy to see that the measured temp is going to be less than the actual bbl temp but the rise should be the same. BBL never got really warm to the touch though. [Think I should build a shooting house then I could control the temperature and remove the effects of the wind. Project for next week [img]/ubbthreads/images/graemlins/crazy.gif[/img]]
Here's some more fuel for the fire:
All bullets were Sierra 2600s (250gr spbts)
All primers were Fed-215s
Loaded round weights are:
4350 loads - 586.9/586.3/589.7 grains
RL-22 loads- 563.4/563.1/563.7 grains
Think about that one for awhile. Case capacities for the 4350 loads were much less than for the RL-22 loads.[img]/ubbthreads/images/graemlins/shocked.gif[/img]
This is why the 338 Win is not a good platform for this swiss navy project except for testing its mechanical aspects.
Shoot the shot.
Watch the temp rise until it steadied out then dropped 0.2 then recorded the highest number.
Then quickly repeat the sequence.
Would have been nice to have a thermocouple epoxied to the bbl, less mass, and a strip chart recorder as I have no idea of what the actual Tstart was for anything other than the first shot. (BTW I don't think even a 12 minute wait gets the bbl back to the original temp.
BTW-a wack w/a plastic mallet removed the test fixture. Then a cloth soaked in Gunk GREEN concentrated biodegradable Concentrated Cleaner plus some digging with the thumb hail removed all eveidence. (Just tho't I'd throw that in, its good stuff)
We'll rerun the speeriment this afternoon. I'm all out of 4350 and can't get enough RL-22 in the modified cases to be reasonable. Think I'll go w/RL-19 or even RL-15???
MOre data added: