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 Post subject: Recycled classic........
PostPosted: Mon Jan 04, 2010 12:43 pm 
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Location: home of the Marshville Festival, Ontario, Canada
A "beater" Crosman Mark I/II gets recycled - in this case, into a new PFT pistol.

I finished this one a couple weeks back - Crosman Mark II, .177 cal, 12" tensioned barrel, 3.5 - 10 X 40 AO/SW scope with illuminated mildot reticule.

Image

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PostPosted: Mon Jan 04, 2010 3:36 pm 
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Location: Coalmont BC
Very nice.... :wink:

I'll show my ignorance once again.... what is a tensioned barrel?.... :oops:

Bob

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Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal; Too many! Springers, Pumpers, CO2, but I love my PCPs and developing them!
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PostPosted: Mon Jan 04, 2010 4:15 pm 
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the barrel is screwed at both end in a casing there is a tention on the barrel because of that

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PostPosted: Mon Jan 04, 2010 8:13 pm 
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rsterne wrote:
Very nice.... :wink:

I'll show my ignorance once again.... what is a tensioned barrel?.... :oops:

Bob

Poil27 pretty much summed it up.

The barrel is under tension, and by changing the degree of tension, the barrel harmonics can be altered, thus "tuning" for accuracy.
Not unlike tuning a guitar string for the correct pitch.


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PostPosted: Mon Jan 04, 2010 8:53 pm 
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Quote:
by changing the degree of tension

I figured that was the concept.... and certainly am aware of barrel harmonics.... Exactly how is this accomplished?....

Bob

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Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal; Too many! Springers, Pumpers, CO2, but I love my PCPs and developing them!
Proud Member of the 2000+fps Club!


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PostPosted: Mon Jan 04, 2010 9:28 pm 
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Location: Nova Scotia, near Halifax
that on my "next gun" list. :shock:
but instead i am building a cosin of that a 1740 gas sipper.

nice work- looks good grey too.
why didn't you go black??? i have to ask.

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PostPosted: Tue Jan 05, 2010 12:49 am 
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rsterne wrote:
Quote:
by changing the degree of tension

I figured that was the concept.... and certainly am aware of barrel harmonics.... Exactly how is this accomplished?....

Bob

By adjusting the tensioning nuts, or, by altering the barrel diameter.


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PostPosted: Tue Jan 05, 2010 12:52 am 
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quickreply7789 wrote:
nice work- looks good grey too.
why didn't you go black??? i have to ask.

Some of the early Mark I pistols were finished in a similar grey colour, and I always liked the looks of them, sooooo.... :)


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PostPosted: Wed Jan 06, 2010 11:24 pm 
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I guess I have to be more specific.... Would it be too much trouble to show how you set up the barrel so that you could adjust the tension with the tensioning nuts.... I have never seen this done, but I do understand the concept.... :shock:

Of course if it's a trade secret, I understand.... :wink:

Bob

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Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal; Too many! Springers, Pumpers, CO2, but I love my PCPs and developing them!
Proud Member of the 2000+fps Club!


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PostPosted: Thu Jan 07, 2010 8:42 pm 
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rsterne wrote:
I guess I have to be more specific.... Would it be too much trouble to show how you set up the barrel so that you could adjust the tension with the tensioning nuts.... I have never seen this done, but I do understand the concept.... :shock:

Of course if it's a trade secret, I understand.... :wink:

Bob

Nope, not a trade secret.

Are you at all familiar with the Crosman Mark I construction? That is a tensioned barrel in it's simplest form - the nut and setscrew at the breach end hold the barrel solid to the frame, while the muzzle end has the nut that snugs everything up. The barrel is held under tension, and altering the tension on the Mark I barrel by a fraction of a turn of the muzzle nut, can make a dramatic improvement to the groups.


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PostPosted: Thu Jan 07, 2010 8:54 pm 
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Quote:
Are you at all familiar with the Crosman Mark I construction?

Nope, never seen one.... So if I understand you correctly, the Mark I already has the hardware in place for a tensioned barrel, you just tweaked it a bit.... I thought you had done extensive mods and was curious about the "nuts and bolts" of what you did....

Thanks for the clarification....

Bob

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Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal; Too many! Springers, Pumpers, CO2, but I love my PCPs and developing them!
Proud Member of the 2000+fps Club!


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PostPosted: Thu Jan 07, 2010 10:09 pm 
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I hadn't heard of a tensioned barrel either. Interesting... !
8)

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PostPosted: Fri Jan 08, 2010 3:02 pm 
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lh wrote:
I hadn't heard of a tensioned barrel either. Interesting... !
8)

IIRC, the Browning Buckmark rifle is just one of the newer guns that uses a tensioned barrel within the carbon fibre sleeve of their lightweight model.


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PostPosted: Fri Jan 08, 2010 10:17 pm 
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Location: Chicago
That's the best MK I have ever seen.


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PostPosted: Tue Feb 02, 2010 7:07 pm 
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I'd love to see some groups 1How does it shoot? Harold MAC1 puts HW barrels on his custom guns and says 1" at 50 yards is common.Ever consider making a detachable shoulder stock like the artillery Luger or the Beeman P1 that attaches under the grip?


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