Some more 2240 chrony results

Some more 2240 chrony results

Joined: July 6th, 2006, 10:11 pm

February 28th, 2009, 9:51 pm #1

I did a couple of more mods to the gun and got the numbers. The graph shows the temp when each test was done. My attempt at building a power adjuster was, to put it politely, an abject failure. All else seems to move in the right direction. What was very interesting was that after I got done with the last test in .22, I installed a 16" .177 barrel. I was expecting to see velocities way up in the 700's but actually saw the velocity drop into the mid-630 FPS range. This particular barrel only has a 1/8" diameter barrel transfer port hole so I'm guessing that this is simply a choke point. The RSD's when using this barrel were also extremely low (0.5% over a 10 shot group) so that lends a little creedence to the small transfer port hole acting as a regulator, albeit one that doesn't allow much in the way of flow.

It is also no surprise that doing these mods is blowing more and more CO2 out of the barrel. I'm probably contributing more to global warming by doing these tests than most of the third world and I'm sure I'm leaving a carbon footprint that has to be Sasquatch-esque. While I didn't show it here, the final test I did was with a much stonger hammer spring and that got me to 670 FPS on the 24 " barrel at 63F. However, it looks like I was only able to get 12 good shots out of a cart before the velocity started to drop like a stone in the ocean. About the only thing left is to wait until the weather here in Pittsburgh warms up so I can see what happens at higher temps.

Here are the mods and the order in which they were done.

Test 1 is stock valve and springs and running off carts. Barrel and valve milled to seat poly tube transfer port. All tests will use Daisy P-Max WC pellets. Standard bolt.
Test 2 adds extended probe bolt.
Test 3 opens exhaust port on valve and barrel xfer port to 11/64" the ID of the poly tube
Test 4 angles valve exhaust port
Test 5 adds a crude power adjuster = about 1/8" shim behind hammer spring
Test 6 removes crude power adjuster and adds weaker valve spring. Same # of turns, wire dia at .0.35" vs.0.044" stock
Test 7 removes 1/2 of the threads on the valve front
Test 8 re-shapes valve stem in exhaust port area



Tony

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Joined: July 6th, 2006, 10:11 pm

February 28th, 2009, 9:53 pm #2

.
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Joined: July 6th, 2006, 10:11 pm

February 28th, 2009, 9:54 pm #3

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Joined: April 2nd, 2003, 2:13 pm

February 28th, 2009, 10:37 pm #4

I did a couple of more mods to the gun and got the numbers. The graph shows the temp when each test was done. My attempt at building a power adjuster was, to put it politely, an abject failure. All else seems to move in the right direction. What was very interesting was that after I got done with the last test in .22, I installed a 16" .177 barrel. I was expecting to see velocities way up in the 700's but actually saw the velocity drop into the mid-630 FPS range. This particular barrel only has a 1/8" diameter barrel transfer port hole so I'm guessing that this is simply a choke point. The RSD's when using this barrel were also extremely low (0.5% over a 10 shot group) so that lends a little creedence to the small transfer port hole acting as a regulator, albeit one that doesn't allow much in the way of flow.

It is also no surprise that doing these mods is blowing more and more CO2 out of the barrel. I'm probably contributing more to global warming by doing these tests than most of the third world and I'm sure I'm leaving a carbon footprint that has to be Sasquatch-esque. While I didn't show it here, the final test I did was with a much stonger hammer spring and that got me to 670 FPS on the 24 " barrel at 63F. However, it looks like I was only able to get 12 good shots out of a cart before the velocity started to drop like a stone in the ocean. About the only thing left is to wait until the weather here in Pittsburgh warms up so I can see what happens at higher temps.

Here are the mods and the order in which they were done.

Test 1 is stock valve and springs and running off carts. Barrel and valve milled to seat poly tube transfer port. All tests will use Daisy P-Max WC pellets. Standard bolt.
Test 2 adds extended probe bolt.
Test 3 opens exhaust port on valve and barrel xfer port to 11/64" the ID of the poly tube
Test 4 angles valve exhaust port
Test 5 adds a crude power adjuster = about 1/8" shim behind hammer spring
Test 6 removes crude power adjuster and adds weaker valve spring. Same # of turns, wire dia at .0.35" vs.0.044" stock
Test 7 removes 1/2 of the threads on the valve front
Test 8 re-shapes valve stem in exhaust port area



Tony
You could try leaving the gun in the warm house for a few hours, then take a couple of quick chrony shots to see what happens...

Good luck,
Lorrin
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Joined: June 11th, 2004, 3:53 pm

March 1st, 2009, 12:16 am #5

I did a couple of more mods to the gun and got the numbers. The graph shows the temp when each test was done. My attempt at building a power adjuster was, to put it politely, an abject failure. All else seems to move in the right direction. What was very interesting was that after I got done with the last test in .22, I installed a 16" .177 barrel. I was expecting to see velocities way up in the 700's but actually saw the velocity drop into the mid-630 FPS range. This particular barrel only has a 1/8" diameter barrel transfer port hole so I'm guessing that this is simply a choke point. The RSD's when using this barrel were also extremely low (0.5% over a 10 shot group) so that lends a little creedence to the small transfer port hole acting as a regulator, albeit one that doesn't allow much in the way of flow.

It is also no surprise that doing these mods is blowing more and more CO2 out of the barrel. I'm probably contributing more to global warming by doing these tests than most of the third world and I'm sure I'm leaving a carbon footprint that has to be Sasquatch-esque. While I didn't show it here, the final test I did was with a much stonger hammer spring and that got me to 670 FPS on the 24 " barrel at 63F. However, it looks like I was only able to get 12 good shots out of a cart before the velocity started to drop like a stone in the ocean. About the only thing left is to wait until the weather here in Pittsburgh warms up so I can see what happens at higher temps.

Here are the mods and the order in which they were done.

Test 1 is stock valve and springs and running off carts. Barrel and valve milled to seat poly tube transfer port. All tests will use Daisy P-Max WC pellets. Standard bolt.
Test 2 adds extended probe bolt.
Test 3 opens exhaust port on valve and barrel xfer port to 11/64" the ID of the poly tube
Test 4 angles valve exhaust port
Test 5 adds a crude power adjuster = about 1/8" shim behind hammer spring
Test 6 removes crude power adjuster and adds weaker valve spring. Same # of turns, wire dia at .0.35" vs.0.044" stock
Test 7 removes 1/2 of the threads on the valve front
Test 8 re-shapes valve stem in exhaust port area



Tony
again, it appears to show that the single most effective way to increase performance is to use a longer barrel. Then the other mods help incrementally, noting that with the longer barrel, they have a more significant effect.

Now we know more clearly how we will gain the most benefit. I guess I'll be digging around for my stashed 24" barrels, stop doubting the wisdom of my longer barreled pistols and put up with the extra length.

Thanks... keep it up.

LUK

Be Well... Tom
Think as though you LIFE depends on it...IT DOES!
"A fear of weapons is a sign of retarded sexual and emotional maturity." - Sigmund Freud
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Joined: August 16th, 2004, 7:32 am

March 1st, 2009, 12:32 am #6

I did a couple of more mods to the gun and got the numbers. The graph shows the temp when each test was done. My attempt at building a power adjuster was, to put it politely, an abject failure. All else seems to move in the right direction. What was very interesting was that after I got done with the last test in .22, I installed a 16" .177 barrel. I was expecting to see velocities way up in the 700's but actually saw the velocity drop into the mid-630 FPS range. This particular barrel only has a 1/8" diameter barrel transfer port hole so I'm guessing that this is simply a choke point. The RSD's when using this barrel were also extremely low (0.5% over a 10 shot group) so that lends a little creedence to the small transfer port hole acting as a regulator, albeit one that doesn't allow much in the way of flow.

It is also no surprise that doing these mods is blowing more and more CO2 out of the barrel. I'm probably contributing more to global warming by doing these tests than most of the third world and I'm sure I'm leaving a carbon footprint that has to be Sasquatch-esque. While I didn't show it here, the final test I did was with a much stonger hammer spring and that got me to 670 FPS on the 24 " barrel at 63F. However, it looks like I was only able to get 12 good shots out of a cart before the velocity started to drop like a stone in the ocean. About the only thing left is to wait until the weather here in Pittsburgh warms up so I can see what happens at higher temps.

Here are the mods and the order in which they were done.

Test 1 is stock valve and springs and running off carts. Barrel and valve milled to seat poly tube transfer port. All tests will use Daisy P-Max WC pellets. Standard bolt.
Test 2 adds extended probe bolt.
Test 3 opens exhaust port on valve and barrel xfer port to 11/64" the ID of the poly tube
Test 4 angles valve exhaust port
Test 5 adds a crude power adjuster = about 1/8" shim behind hammer spring
Test 6 removes crude power adjuster and adds weaker valve spring. Same # of turns, wire dia at .0.35" vs.0.044" stock
Test 7 removes 1/2 of the threads on the valve front
Test 8 re-shapes valve stem in exhaust port area



Tony
about $20 shipped, money well spent.

Great numbers once again Tony, thanks!



Last edited by bigbore on March 1st, 2009, 4:49 am, edited 1 time in total.
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Joined: February 17th, 2009, 4:02 am

March 1st, 2009, 1:01 am #7

I had looked at the part numbers for the 2300S version's power adjust part...ism that what you're referring to?
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Joined: July 6th, 2006, 10:11 pm

March 1st, 2009, 1:28 am #8

again, it appears to show that the single most effective way to increase performance is to use a longer barrel. Then the other mods help incrementally, noting that with the longer barrel, they have a more significant effect.

Now we know more clearly how we will gain the most benefit. I guess I'll be digging around for my stashed 24" barrels, stop doubting the wisdom of my longer barreled pistols and put up with the extra length.

Thanks... keep it up.

LUK

Be Well... Tom
Think as though you LIFE depends on it...IT DOES!
"A fear of weapons is a sign of retarded sexual and emotional maturity." - Sigmund Freud
The longer the barrel, the greater the baseline gain and the greater the incremental gains from the common mods. The harder hammer spring I used really jumped the FPS and I need to do some more with that later.

I'd say that the heirarchy of mods is:

Longer barrel

Bigger ports

Reshape valve exhaust

Weaker valve/harder hammer spring

Of course, the poly port mod is good for sealing but that alone doesn't bump the FPS unless the other stuff is done.

I'll do another post when the temps are up.

Thanks for looking!

Tony
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Joined: June 11th, 2004, 3:53 pm

March 1st, 2009, 4:25 am #9

helps us, me anyway, to evaluate where to put my time and money to get the best and what the results of my choices will be.

For instance, I can get significantly better performance by adding a 24" barrel to my hunting carbine, but it will handle different, and be harder to case when carried and it won't 'look' the same. So I'll accept the trade off.

And, I'm happy with 12" of barrel on my 2240 even though I planned on a 10" barrel even if it's looks a little odd being so long knowing I get more performance and it still fits in the case.

Just my examples...

LUK

Be Well... Tom
Think as though you LIFE depends on it...IT DOES!
"A fear of weapons is a sign of retarded sexual and emotional maturity." - Sigmund Freud
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Joined: August 16th, 2004, 7:32 am

March 1st, 2009, 4:48 am #10

I had looked at the part numbers for the 2300S version's power adjust part...ism that what you're referring to?
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