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PostPosted: Tue Feb 07, 2017 6:06 pm 
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Joined: Sat Jan 14, 2017 10:19 pm
Posts: 40
Location: Stony Plain, Alberta
Did an RVA mod for the Bam B-50 even before all the breech and caliber mods, in an effort to reduce cocking effort. After the new breech, I decided to build a new air-valve.
Attachment:
File comment: The new valve stem seal was machined out of peek and stainless steel insert for the new air-valve.
23. New Valve-stem seal out of peek.jpeg
23. New Valve-stem seal out of peek.jpeg [ 163.29 KiB | Viewed 746 times ]

Attachment:
File comment: New air valve made out of 7075 aluminum, with stainless steel insert pressed in.
24. New Air-valve assembled.jpeg
24. New Air-valve assembled.jpeg [ 194.22 KiB | Viewed 746 times ]


My chrony was broke down, so I couldn't test for velocity. On test-firing, I was breaking the sound barrier, with JSB Jumbo Monsters at 2100 psi. Also air consumption was atrocious. The continual 'bbbraaaphhhh' that told me there was massive amount of air being wasted. So I playing with the idea of rebounding hammer, such as is found on my Cooey single-shot shotgun.

Then the article on the stopped spring guide came out, and that solved all my problems. That in conjunction with RVA, brought my velocity with 14.3 grain Crosman Premieres down to a 1040 fps at 1900 psi. Accuracy is exceptional, if I do my part. I was able to get a new velocity reading, because I got my Chrony fixed.

When I first tested, groups of 5 shots were slightly bigger than one pellet hole, at 40 yards. As a matter of fact, I initially thought I hit the target once, and then I thought I missed it for the next four shots. On closer examination, the one hole just got a little bit bigger.

Cocking effort is very easy now. It feeds very smoothly. And I am totally impressed with it.
Attachment:
25. Assembled & Anodized Bam B-50.JPG
25. Assembled & Anodized Bam B-50.JPG [ 61.29 KiB | Viewed 746 times ]


If you happen to be planning on attending the Hunt Mania Sportsman Show in Camrose, Alberta this weekend, February 10, 11, 12, 2016. I will be there with my son and Shop- Partner, Jacob Balan. I will have my:
-Bam B-50
-QB78, with repeating breech and modified cocking system
-Crosman 2240, with repeating breech

If you want to see these up close and personal, drop by our table.

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PostPosted: Tue Feb 07, 2017 8:27 pm 
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Joined: Tue Jun 03, 2008 5:46 pm
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Location: Canada
Might take that in...see how things work out.

Al


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PostPosted: Tue Feb 07, 2017 11:08 pm 
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Joined: Sat Dec 17, 2011 10:04 pm
Posts: 525
Location: Komoka Ont.
Nice work, how does that magazine stay in place and did you have to change the bolt much? I've never actually seen up close a repeating air rifle, I hate to admit it.

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PostPosted: Wed Feb 08, 2017 1:03 am 
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Location: Stony Plain, Alberta
Hi Garth,
I missed putting in some pics of the barrel mod and theres a .062" section of the barrel which protrudes into the clip slot. The first picture below, shows the groove made for the o-ring. (I didn't know how to seal the barrel/chamber until I read one of rsterne's posts, which showed putting the groove in the end of the barrel.)

The second picture next to it, shows the barrel protruding into the breech.
Attachment:
O-ring groove & barrel in clip-slot.png
O-ring groove & barrel in clip-slot.png [ 686.3 KiB | Viewed 673 times ]


In the next picture, with the components assembled, you can see the barrel protrusion next to the clip in the breech.

Attachment:
Barrel Breech & Clip Assembled.IMG_4052.jpeg
Barrel Breech & Clip Assembled.IMG_4052.jpeg [ 381.8 KiB | Viewed 673 times ]



A new bolt was machined and the section that slides through the clip is narrowed down to slightly larger than the pellet diameter, so that it pushes the pellet out of the clip into the barrel. Has to be long enough to slip past the transfer port and it seals on the o-ring that was placed in the groove at the end of the barrel.
Attachment:
The Bolt & Cocking pin.png
The Bolt & Cocking pin.png [ 435.41 KiB | Viewed 673 times ]


I had never before seen a repeating airgun either. Just read about them and saw some pictures long ago and knew one day I would build one. The clip is self-indexing, every time you pull the bolt back, the clip puts another pellet into place. However, if for any reason you have to pull the bolt back a second time before firing, you have to remove the clip or you will double load.

Thanks for asking, Garth. Due to the fact that I am new to posting and barely computer-literate, my 3 posts on this topic seem quite helter-skelter. I still have to learn how to keep everything on one topic together in a thread. Adding the above steps of my Bam-project makes my posts more complete.

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PostPosted: Wed Feb 08, 2017 1:07 am 
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Location: Stony Plain, Alberta
Gippeto wrote:
Might take that in...see how things work out.

Al




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If your airgun is broken, fix it. If it works, you CAN make it work better. Usually...


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PostPosted: Wed Feb 08, 2017 1:17 am 
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Joined: Sat Jan 14, 2017 10:19 pm
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Location: Stony Plain, Alberta
Be very nice to meet you there, if you decide to take in the Camrose event. Maybe I could get some pointers on how to do my posts, so everything is on one page. It's my first time posting, and I'm 'shooting in the dark' here.


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If your airgun is broken, fix it. If it works, you CAN make it work better. Usually...


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PostPosted: Sat Apr 01, 2017 11:24 am 
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Joined: Sat Nov 05, 2016 10:52 am
Posts: 2938
Location: Caronport, Saskatchewan
Great work! Too bad they quit making those B-50s, sounds like you've made it into a great gun! I see there is a couple left on the Canadian airgun forum store.

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