Benjiman 397 results are in.

Benjiman 397 results are in.

Joined: April 1st, 2009, 3:18 am

May 11th, 2012, 12:56 pm #1

Few things first. For whatever reason, it seems that brass is_not_ my metal. Cannot seem to ever get any paint to stick to it. For the finish, a bake on paint was used, then a coat of bed liner over that. Still, the small edge areas, along the tube slot, pin holes, breech loading area, so on, the paint chips off revealing the brass underneath. May not annoy some, but I find it to be very annoying - especially after such meticulous, careful prep. Ho hum. I think it will be stripped - AGAIN and just shined up to bare brass then sealed. Gosh. Think I have come up with an alternative to saying "a pain in my a$$". From now on, the phrase shall be "a pain in my brass". So fitting after dealing with the Benji. Crosman must use a powder coat applied with electric current. Not sure.

To spare all of you endless shot strings numbers, what has been done here is the average of three shots per stroke amount. For example, one stroke, three shots taken. Two strokes, three shots taken and average found, etc. Using Crosman, CPHP, .177cal, 7.8-7.9 grains.

Numbers will be posted when I return later from a daddy-daughter day fishing with her grandpa. We should only be gone a few hours. The little one was wanting to go fish with grandpa and daddy with bamboo poles. So we have toget some, then go fish off a bank. She saw this watching an educational program and absolutely has to try it. So, we will.

When we return, the plan is to run the Chrony again for varification. This chronograph is on loan as mine was shot and killed on the mean streets of my back yard .

"The majority of things in our lives are created by folks no smarter than the rest. Afterall, the world is comprised, and operated by C average people intellctually, academically, and morally. These people are often the great pioneers that set the precedent for what excellence should be."
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Joined: April 28th, 2010, 12:23 am

May 11th, 2012, 2:21 pm #2

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Joined: November 28th, 2002, 6:26 pm

May 11th, 2012, 5:21 pm #3

...the steel tube. Otherwise the much greater rate of expansion/contraction with temperature of the stock brass barrel would fatigue and fracture the solder joint.

Of course, you could forego the direct bond between barrel and tube. But then how much of the original gun's design and tradition would be left?

Of course, I guess that's just the old "slippery slope" all modders face. How much "modd'ing" is possible before - piece by piece - for all practical purposes - the original gun is simply gone?

Steve
Last edited by pneuguy on May 11th, 2012, 5:22 pm, edited 1 time in total.
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Joined: April 28th, 2010, 12:23 am

May 11th, 2012, 6:35 pm #4

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Joined: April 1st, 2009, 3:18 am

May 11th, 2012, 8:40 pm #5

Few things first. For whatever reason, it seems that brass is_not_ my metal. Cannot seem to ever get any paint to stick to it. For the finish, a bake on paint was used, then a coat of bed liner over that. Still, the small edge areas, along the tube slot, pin holes, breech loading area, so on, the paint chips off revealing the brass underneath. May not annoy some, but I find it to be very annoying - especially after such meticulous, careful prep. Ho hum. I think it will be stripped - AGAIN and just shined up to bare brass then sealed. Gosh. Think I have come up with an alternative to saying "a pain in my a$$". From now on, the phrase shall be "a pain in my brass". So fitting after dealing with the Benji. Crosman must use a powder coat applied with electric current. Not sure.

To spare all of you endless shot strings numbers, what has been done here is the average of three shots per stroke amount. For example, one stroke, three shots taken. Two strokes, three shots taken and average found, etc. Using Crosman, CPHP, .177cal, 7.8-7.9 grains.

Numbers will be posted when I return later from a daddy-daughter day fishing with her grandpa. We should only be gone a few hours. The little one was wanting to go fish with grandpa and daddy with bamboo poles. So we have toget some, then go fish off a bank. She saw this watching an educational program and absolutely has to try it. So, we will.

When we return, the plan is to run the Chrony again for varification. This chronograph is on loan as mine was shot and killed on the mean streets of my back yard .

"The majority of things in our lives are created by folks no smarter than the rest. Afterall, the world is comprised, and operated by C average people intellctually, academically, and morally. These people are often the great pioneers that set the precedent for what excellence should be."
These nuumbers are taken from the average velocity of five shots each stroke input. Deviation is no more than 5fps from shot to shot.

The numbers represent the total number of strokes used.

1.(one stroke) 396fps
2.(two strokes) 557fps
3.(three strokes) 654fps
4.(four strokes) 714fps

Above four strokes, air is remaining in the valve. Other measures could be applied to cancel this out, but is very nice to shoot where it is at (*see note at bottom). One stroke is plenty for plinking or paper punching.

Much easier to pump than anticipated. Perhaps due to the wood extending the lever, pumping is easy.

Honestly, a bit more umph can be pulled out of it. As it is, it 'should' be within the margines of durability. Too much, the gun will not last.

NOTE
The stem head has been removed for another project when it was used. I ran out of exhaust stem seals... At any rate, using the factory stem seal will further reduce the valve volume ever so slightly. Though slight, very little is ever needed for gains in the one-pump shooting mode when the valve is already reduced. With that, the multi-pump mode may see diminished gains.

Pictures will be posted later. Computer had to have everything reloaded a week ago due to a nasty bug Insight had... Got to reinstall my BlackBerry dasboard...

"The majority of things in our lives are created by folks no smarter than the rest. Afterall, the world is comprised, and operated by C average people intellctually, academically, and morally. These people are often the great pioneers that set the precedent for what excellence should be."
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Joined: April 28th, 2010, 12:23 am

May 11th, 2012, 10:46 pm #6

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Joined: April 1st, 2009, 3:18 am

May 11th, 2012, 11:48 pm #7

...was in the order of the 530's.

A new weep hole has been drilled due the shorter assembled valve. The hole is 1/2" further down the tube. Piston is a Mellon made flat top piston. He turned the aluminum to the specs I sent him drawn in Microsoft paint.

Occasionally, while shooting it over the Chrony, it would hit 408fps. But the average is right about at 400fps figure guestimated. The second pump velocity leaves me shy of the guestimated figure of 600fps. But, hey. You can't win them all. I truly suspect using an unmodifed exhaust stim will make the numbers guestimated come to life.

"The majority of things in our lives are created by folks no smarter than the rest. Afterall, the world is comprised, and operated by C average people intellctually, academically, and morally. These people are often the great pioneers that set the precedent for what excellence should be."
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Joined: May 31st, 2005, 5:24 am

May 12th, 2012, 6:06 am #8

Few things first. For whatever reason, it seems that brass is_not_ my metal. Cannot seem to ever get any paint to stick to it. For the finish, a bake on paint was used, then a coat of bed liner over that. Still, the small edge areas, along the tube slot, pin holes, breech loading area, so on, the paint chips off revealing the brass underneath. May not annoy some, but I find it to be very annoying - especially after such meticulous, careful prep. Ho hum. I think it will be stripped - AGAIN and just shined up to bare brass then sealed. Gosh. Think I have come up with an alternative to saying "a pain in my a$$". From now on, the phrase shall be "a pain in my brass". So fitting after dealing with the Benji. Crosman must use a powder coat applied with electric current. Not sure.

To spare all of you endless shot strings numbers, what has been done here is the average of three shots per stroke amount. For example, one stroke, three shots taken. Two strokes, three shots taken and average found, etc. Using Crosman, CPHP, .177cal, 7.8-7.9 grains.

Numbers will be posted when I return later from a daddy-daughter day fishing with her grandpa. We should only be gone a few hours. The little one was wanting to go fish with grandpa and daddy with bamboo poles. So we have toget some, then go fish off a bank. She saw this watching an educational program and absolutely has to try it. So, we will.

When we return, the plan is to run the Chrony again for varification. This chronograph is on loan as mine was shot and killed on the mean streets of my back yard .

"The majority of things in our lives are created by folks no smarter than the rest. Afterall, the world is comprised, and operated by C average people intellctually, academically, and morally. These people are often the great pioneers that set the precedent for what excellence should be."
what kind of paint is used on them from the factory. if it sticks on the outside like it does the first inch inside the muzzle you would never have to worry about it chipping or coming off. the factory oversprays every one of them in .177 and .22. haven't tried a new dan in .20 but i'm sure its the same thing. i've had them that wouldn't group under an inch or inch and a half off the bench at 25 yards. take a bunch of q-tips and a nylon bore brush and very carefully so you don't get it on the outside start applying laquer thinner with the q-tip, then scrub with the brush until it evaporates, then repeat, and repeat, and repeat. i've had to work on one gun sometimes an hour ot two to finally get all that paint out. then the gun would become a tack driver. crosman could plug each gun with a rubber plug to prevent this but they won't for some reason. anyone know of something that'll cut that paint faster than laquer thinner please let me know.
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Joined: February 9th, 2006, 10:35 pm

May 12th, 2012, 11:05 am #9

I used carb and choke cleaner to remove the paint in the muzzle of my 392. Works like a charm. Got a drop on the front sight and had to touch it up.

I don't think it's powder coat. Probably some kind of baked on self priming stuff.

I plink, therefore I am.
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Joined: February 9th, 2006, 10:35 pm

May 12th, 2012, 11:07 am #10

These nuumbers are taken from the average velocity of five shots each stroke input. Deviation is no more than 5fps from shot to shot.

The numbers represent the total number of strokes used.

1.(one stroke) 396fps
2.(two strokes) 557fps
3.(three strokes) 654fps
4.(four strokes) 714fps

Above four strokes, air is remaining in the valve. Other measures could be applied to cancel this out, but is very nice to shoot where it is at (*see note at bottom). One stroke is plenty for plinking or paper punching.

Much easier to pump than anticipated. Perhaps due to the wood extending the lever, pumping is easy.

Honestly, a bit more umph can be pulled out of it. As it is, it 'should' be within the margines of durability. Too much, the gun will not last.

NOTE
The stem head has been removed for another project when it was used. I ran out of exhaust stem seals... At any rate, using the factory stem seal will further reduce the valve volume ever so slightly. Though slight, very little is ever needed for gains in the one-pump shooting mode when the valve is already reduced. With that, the multi-pump mode may see diminished gains.

Pictures will be posted later. Computer had to have everything reloaded a week ago due to a nasty bug Insight had... Got to reinstall my BlackBerry dasboard...

"The majority of things in our lives are created by folks no smarter than the rest. Afterall, the world is comprised, and operated by C average people intellctually, academically, and morally. These people are often the great pioneers that set the precedent for what excellence should be."
714 on 4 pumps? Cool, but then it's a .177 right?
Any ideas what it could do in .20 or .22?

Anyway, cool stuff Phil.

I plink, therefore I am.
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