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 Post subject: Re: Customized B51 .22
PostPosted: Sun Jan 19, 2014 9:42 am 
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Joined: Sat Dec 17, 2011 10:04 pm
Posts: 525
Location: Komoka Ont.
Turning down the valve dia. is something I wanted to try, do you recall what size you made it. I had read that in could increase power by making the valve easier to open. Maybe thats why yours is such a canon.

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 Post subject: Re: Customized B51 .22
PostPosted: Sun Jan 19, 2014 9:43 pm 
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Joined: Tue Aug 30, 2011 9:56 pm
Posts: 74
Location: West Coast
GarthThomas wrote:
Turning down the valve dia. is something I wanted to try, do you recall what size you made it. I had read that in could increase power by making the valve easier to open. Maybe thats why yours is such a canon.


I don't remember the numbers, but It wasn't very much. I made the new valve head slightly smaller. I'd say going .02" smaller would be a good place to start.

Mike


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 Post subject: Re: Customized B51 .22
PostPosted: Sat Jan 25, 2014 7:45 pm 
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Posts: 74
Location: West Coast
I removed the de-pinger from my air cylinder. I was curious to see how many more shots I would gain from the extra volume. I filled the gun to 3000psi and shot 45 shots down to 1650psi the results are not exactly what I expected.

864 920 870
861 917 865
853 919 861
867 915 855
868 920 855 1650psi
881 917
884 911
890 914
879 912
890 909
890 907
897 905
902 896
905 894
916 895
911 888
911 883
909 877
918 875
908 872

I find the overall lower velocity of this string compared to my previous stings. I was expecting the velocity to stay (roughly) the same and gain some shots. but it looks like it lowered the FPS and gained more shots. I'll do some more numbers later.

Mike


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 Post subject: Re: Customized B51 .22
PostPosted: Sat Jan 25, 2014 10:40 pm 
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Joined: Sat Dec 17, 2011 10:04 pm
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Location: Komoka Ont.
That's quite a difference in velocity, what sort of a de-pinger do you use?

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 Post subject: Re: Customized B51 .22
PostPosted: Sat Jan 25, 2014 11:43 pm 
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Location: West Coast
The de-pinger was a delrin disk about 3/8" thick with and O-ring around the circumference. It had a 1/8" hole through the center. I placed it mid way through the cylinder. It worked excellent for its intended purpose. The ringing of the cylinder doesn't bother me very much, so I think I'll keep it out. Maybe I will adjust the hammer set screw some more to see if I can smooth out that curve a bit more

Mike


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 Post subject: Re: Customized B51 .22
PostPosted: Sun Jan 26, 2014 8:52 pm 
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Location: West Coast
I noticed a leak in the endcap. I submerged the reservoir in water and discovered it was comming from the endcap o-rings. After taking the endcap off I noticed a scratch in the tube where the one of the o-rings seal. I polished it out on the lathe with fine sandpaper. It seals now and I adjusted the hammer set screw, and the gun now shoots an average of 931 fps over a 35 shot string starting at 200 bar (2900 psi) down to 135 bar (1960psi). Extreme spread of 49 fps(5.3%). I think this is adequate for hunting. The next step would be installing a regulator. But at this power, im not sure a regulator would work.

Mike


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 Post subject: Re: Customized B51 .22
PostPosted: Sun Jan 26, 2014 10:08 pm 
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Joined: Sat Dec 17, 2011 10:04 pm
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Location: Komoka Ont.
I think you would be shooting at lower velocity to use a reg. I also think that your rifle is performing very well and if you prefer having that much power then don't touch it. I don't know if I've ever read of many B50/51's working as well, I wonder if that barrel is contributing to the efficiency if its longer than stock and maybe even tighter.

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 Post subject: Re: Customized B51 .22
PostPosted: Mon Jan 27, 2014 2:56 am 
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Joined: Tue Aug 30, 2011 9:56 pm
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Location: West Coast
I think the barrel has something to do with it. It's almost 4" longer than the original.

The stock re-finishing is done. I changed the front forearm a bit and stained with minwax walnut stain. The covered it with 16 light coats of polyurethane gloss.

Image

Mike


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