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Old 09-01-2008, 11:04 AM   #21 (permalink)
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Originally Posted by Harbinger[TG] View Post
They should have some barrels in stock, depends on what gun its going on.
dang, 58 + 15 for widgets (since .685 is WAY TOO BIG) + 45 for porting.....

$118 barrel?

yeah, does anyone have one I can borrow for a week or so?
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Old 09-01-2008, 02:15 PM   #22 (permalink)
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Quote:
Originally Posted by brycelarson View Post
dang, 58 + 15 for widgets (since .685 is WAY TOO BIG) + 45 for porting.....

$118 barrel?

yeah, does anyone have one I can borrow for a week or so?
I only have the one 1K barrel, but I am sure some people have loads of barrels.
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Old 09-01-2008, 02:22 PM   #23 (permalink)
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CP and I are planning to use our grid board on a paint to barrel match to test for accuracy at 50'.

When we pick a date I would love to get a loaner brass barrel to put into the test.

If anyone is willing to loan a barrel to us for the test please hit me via PM. I'm looking for something like a 12" ported barrel - wedgets aren't necessary - but would be fine. It needs to be cocker threaded - it'll be used on a well-tuned sniper.

The format of the test will be exactly like the backspin bolt test - each shot will be plotted, we'll post up the x and y data for all barrel sizes, taking only the shots inside our velocity limits.
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Old 09-01-2008, 03:44 PM   #24 (permalink)
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Originally Posted by brycelarson View Post
response in red
The ball flattens out on impact and expands around its mid section then springs back to its regular shape.
Well a Paintball does this when the gas that propels the ball slams into it from behind.

problem with this theory is that in the high speed videos that TK did the ball show minimal distortion when the gas hits it - it's just not that dramatic. How much do PPS barrels expand in the middle?
it's not a problem at all.
the barrel only expends in the mid-section by a matter of a few thousandths of an inch.
this amount of split second deformation is both very difficult to see and more important than you might think.
drill and hone a hole to be 0.5000"
and turn & hone a shaft that is 0.5000" (if you can find machines that accurate)
now try to put the shaft into that hole.
guess what, it wont go with out lots of force behind it.
some of the most secure press fits are less than 0.005"
and they are pretty well permanent.
now put the shaft in the freezer and the part with the hole in it in the oven at 400F for an hour.
with the shaft fresh out of the freezer,
try to put it in the part with the hole in it strait out of the oven while it's still at 400F...
bet it fits now.
because the hole expanded with the heat by 0.001" or 0.002"
and the Shaft contracted by the same amount.
once they return to room temperature, try to pull them a part...

GOOD LUCK!!

and the hole and shaft are the exact same size.
if the part with the hole had thin enough walls,
or was a soft material like Aluminum,
it could split if the shaft in this example were just 0.002" over size.
so that couple of thousandths of an inch can make a hell of a difference.

for reference a human hair is approximately 0.003" on average.
Red Hair usually being finer and the RPH being finest used for measuring in most shops. (PM me for meaning of RPH if unsure)

now at 280 FPS the ball is moving at 3360 inches per second.
that ball will clear the 8" control bore section of the barrel in 0.0023809 seconds.

so the ball expands by approximately 0.003" for 0.0000992 seconds (time based on .250" of travel) causing a press fit level over pressure for approximately .250" of travel.
the over pressure is too small and too fast to see with the images shot by Tom Kaye.
great footage, but not accurate enough to measure the change.
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Old 09-01-2008, 04:31 PM   #25 (permalink)
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^^good point illustrated with a great example^^

Quote:
Originally Posted by brycelarson View Post
response in red
Originally Posted by LK-13
The ball flattens out on impact and expands around its mid section then springs back to its regular shape.
Well a Paintball does this when the gas that propels the ball slams into it from behind.

problem with this theory is that in the high speed videos that TK did the ball show minimal distortion when the gas hits it - it's just not that dramtic. How much do PPS barrels expand in the middle?

Sorry paint to barrel match dosen’t really work the way the people selling you barrels would like you to think it does.

you're correct, as cocker punk and I have proven - paint to barrel match doesn't work like people think. The tighter the barrel the better consistency and efficiency. Having an over-bored center is only going to waste propellant

Trouble with a Flat Line barrel is the ball tends too loose much of its forward velocity because of the energy lost to the barrel.

yup, they are gas hogs - because a flatline barrel has a really, really big ID

but don't believe me.
get one (buy or borrow) and try it out for yourself.
bet you will be glad you did.

I would love to actually put a PPS barrel to the test. What's the waiting time on ordering a new on from Palmers? I'm sure if it didn't actually perform better someone would still be willing to buy it here - right?
Actually it is personal arrogance and scientific falsehood to assert that your and cockerpunk have proven anything. You have done some great testing and taken a lot of efforts to control variables and deserve to be applauded. If you had tested a pps barrel I would give your findings great weight in my decision. But one test of anything dose not a scientific proof make my lad. Now repeat them 10, 20, 100 times and maybe you can claim to have proven something but right now you have nothing more than some very interesting results.
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Old 09-01-2008, 04:48 PM   #26 (permalink)
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Actually it is personal arrogance and scientific falsehood to assert that your and cockerpunk have proven anything. You have done some great testing and taken a lot of efforts to control variables and deserve to be applauded. If you had tested a pps barrel I would give your findings great weight in my decision. But one test of anything dose not a scientific proof make my lad. Now repeat them 10, 20, 100 times and maybe you can claim to have proven something but right now you have nothing more than some very interesting results.
if that is what you require to understand, then we cannot provide enough evidence to prove it to you. sorry.

however, if you want to prove something to us, you need to do at least our level of testing, and find things that conflict with our tests.

so, ball is in your court. we have evidence, lets see yours?

also, in what test would you have liked to see a PPS barrel? so far we have only been dealing with bore size, not the profile or type of barrel. where would you have liked to see a PPS barrel, and what would it show you?

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Old 09-01-2008, 05:05 PM   #27 (permalink)
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Bryce, you can try calling PPS to see if they might have a used barrel you can borrow.
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Old 09-01-2008, 05:23 PM   #28 (permalink)
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Evidence of what cockerpunk? I have made no assertions. Other than to state fact that a single experiment is not conclusive proof. I am in no way trying to knock what you have done. I have watched and am very impressed by your efforts.
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Old 09-02-2008, 02:37 AM   #29 (permalink)
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Now repeat them 10, 20, 100 times and maybe you can claim to have proven something but right now you have nothing more than some very interesting results.
we did repeat them - we had a sample size of 20 - which is statistically really good. we didn't just shoot each barrel once and then write something down.

We're working on getting a PPS barrel to include on our accuracy tests - I just got a great offer from LK-13 that should make it happen. The problem I see with that - is that you've already said that our last test didn't prove anything - but then you also said that if it contained a PPS barrel then it might - so I don't know that even after testing the PPS barrel if you'll admit that the test was valid.

However, that said, we're not out to convince everyone, just to try to shine some light on topics that are entrenched in non-scientific evidence.

Thanks for the good words about our testing - we're always open to suggestions and we're constantly trying to improve our tests.
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