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PostPosted: Mon Oct 30, 2017 3:22 pm 
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I picked up one of these yesterday, still available for sale so I don't know if it qualifies as an antique but it certainly looks like one, being based on the Crosman 160 rifle design from the 60s but fitted with a 32 gauge barrel with a removable bolt allowing darts to be loaded.

In my enthusiasm to take it apart, I forgot to take a "before" picture, but here's a similar example fitted with a scope:

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Here it is broken down:

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Trigger detail, a much cruder affair than the original 160 trigger and the return spring pushes directly on the stock. Clearly veterinarians are not as picky as target shooters. Note the two grooves on the hammer that allow for a high/low power setting to be selected:

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Valve body and stem detail, in spite of the relatively massive 0.5" bore the transfer port is a mere 5/32" diameter, presumably unchanged from the original 160 valve. The barrel is also rifled, with 8 shallow right hand grooves, which is unusual given that tranquilizer darts are usually drag stabilized.

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Barrel markings identifying it as a "Red's Special", presumably an older variation of the one currently being sold as a "Long Range Rifle Type Projector". I believe the current version is made for a single CO2 cartridge, while this example takes two back to back.

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I'm not sure if I should reseal it and keep it as is, or redo the internals to turn it into a big bore PCP. As it is I doubt it would have any useful velocity with "proper" projectiles given the tiny transfer port, but it seems to have some potential if the rifling would be sufficient to stabilize such projectiles.

That being said, I already have a Farco Air Shotgun in this caliber.


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PostPosted: Mon Oct 30, 2017 3:50 pm 
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Hmmmmm.......52cal pellets anyone lol

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PostPosted: Mon Oct 30, 2017 4:45 pm 
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With the air pushing from behind, the rifling will cause a slight spiral which will merely help initial stabilization. Any wobble prior to the shuttle-cock stabilization will decrease the BC, increase drop and decrease accuracy. I can "see" the possible benefits of rifling 'starting' rotation of the dart.

Conversely, study has shown that most or all shotgun bores have a slight & usually invisible spiraling inside the bores caused during the reaming of the drilled bore. This usually invisible spiraling causes tight fitting plastic wads to turn or spiral in the bore as they travel down it.

The Russian International Team captains of their trap and skeet teams recognized this spiraling due to photographing emerging shot cups and shot columns noting they were twisting in flight although there was no rifling visible in the bores. When steps were taken to eliminate or stop this twisting or rotating of the wads and thus shot columns, pattern densities increased & the Russian teams were unbeatable - for a year or two.

Most all international teams (gun smiths) use variations of the Russian chokes & bore designs & are on a level playing field, again.

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PostPosted: Mon Oct 30, 2017 5:46 pm 
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Fair point, I can see it being useful to stabilize the dart especially at low subsonic velocities.

In the meantime I receiver a reply from Palmer, they could not provide me with an exact manufacturing date but the serial number would have been from the 70s, making me less inclined to want to butcher it as a project.


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PostPosted: Fri Nov 03, 2017 10:07 am 
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A little update, I machined a two part fill nipple with check valve held by the original cap that holds pressure well:

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This allowed for some testing at 1200 psi with my 3 stage Chinese pump which is still working well, very happy with it so far.

I tried with 3/8" steel ball bearings in 50 cal muzzleloader sabots as well as a dummy dart I machined to get an idea of how it would perform with the sort of projectiles it was intended for:

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The dart weights 8.84 grams, 3.54 grams for the steel ball and 0.68 grams for the sabot. Filling to 1200 psi for each shot I got an average of 357 fps for the steel ball and 254 fps for the dart, a fair 15 and 20 ft lbs respectively. It's worth noting that the valve body is effectively blocked off by the steel pin that acts as a spring guide for the valve stem spring as well as a piercer for one of the CO2 cartridges as it was intended to be used, which turns it into a "firing chamber" that might be limiting performance. More testing for accuracy and damage shots to follow eventually.


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PostPosted: Wed Nov 08, 2017 12:57 pm 
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Finally got round to making a test video: https://youtu.be/7KPhaYSg4uo

Some detail images:

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PostPosted: Wed Nov 08, 2017 6:32 pm 
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hey PZAM little off topic but what camera did you use to snap those picture.. ?

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PostPosted: Thu Nov 09, 2017 10:09 am 
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This beauty, sadly not my own.


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PostPosted: Thu Nov 09, 2017 10:38 am 
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cool thanks
very similar to the point and shoot that i use,
im guessing your using very good lighting 8)

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PostPosted: Thu Nov 09, 2017 11:10 am 
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Quite the opposite, little trick I picked up from scale modellers - relatively poor lighting but using a tripod and long exposure time (5-15 seconds depending on ambient light).


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 Post subject: D ft
PostPosted: Thu Nov 09, 2017 11:28 am 
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Interesting project.... You are correct that the piercing pin is keeping air from flowing freely into the valve, and likely limiting performance....

One comment about the brass male QD fitting you made.... It's hard to tell from the angle of the photo, but it appears to me that there is the beginnings of dents on the shoulder where the balls of the female Foster are gripping.... Check that and if you are seeing ANY dents appearing, then do NOT increase your fill pressure.... as they are an indication you are exceeding the yield strength of the brass.... Using steel is a better idea for anything beyond CO2 pressures....

Bob

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 Post subject: Re: D ft
PostPosted: Thu Nov 09, 2017 2:33 pm 
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Thank you Bob for your comments.

rsterne wrote:
You are correct that the piercing pin is keeping air from flowing freely into the valve, and likely limiting performance....


I think I'll leave it as-is, I like this more for the "curio" value so no point in having it shoot much harder.

Quote:
One comment about the brass male QD fitting you made.... It's hard to tell from the angle of the photo, but it appears to me that there is the beginnings of dents on the shoulder where the balls of the female Foster are gripping.... Check that and if you are seeing ANY dents appearing, then do NOT increase your fill pressure.... as they are an indication you are exceeding the yield strength of the brass.... Using steel is a better idea for anything beyond CO2 pressures....


Well spotted, there are indeed some minute indentations on the nipple. I figured 1200 psi being "CO2 on a hot day" would be the limit of what the original tube was made for and had no intention of taking it any further.

Quote:
the shoulder where the balls of the female Foster are gripping


So glad to be on a forum where that phrase makes perfect sense :D


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PostPosted: Thu Nov 09, 2017 3:36 pm 
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PZAM wrote:
Quite the opposite, little trick I picked up from scale modellers - relatively poor lighting but using a tripod and long exposure time 5-15 seconds depending on ambient light).

yes that would do it ... 8)

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