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30cal B51
https://www.airgunforum.ca/forums/topic80316.html
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Author:  Voltar1 [ Sun Aug 12, 2018 11:31 pm ]
Post subject:  30cal B51

Good progress today on a 30cal conversion for a BAM B51.
Made a breech with up sized bolt and cocking lug to handle the larger bore.
Big ports, probe less bolt and maximized hammer stroke. Seems perky so will try for numbers later this week.
This barrel is an rsterne/seanp designed for the JSB pellet, should be a real shooter!
Walter

Author:  FRANK [ Sun Aug 12, 2018 11:40 pm ]
Post subject:  Re: 30cal B51

Welcome Back Walter

and will wait for updates on this new project, sounds very interesting.

Author:  Edmonton<500 [ Mon Aug 13, 2018 2:10 am ]
Post subject:  Re: 30cal B51

Great to see you back, Walter.

Author:  paddyfritz [ Wed Aug 15, 2018 11:06 am ]
Post subject:  Re: 30cal B51

Sounds cool.

Author:  rsterne [ Wed Aug 15, 2018 5:43 pm ]
Post subject:  Re: 30cal B51

Cool project, Walter.... If you haven't seen it, I did a .22 cal that hit over 50 FPE.... topic65795.html

You might find some of the things I found (and changed) of interest.... or maybe not.... :wink:

Bob

Author:  Cadeau [ Wed Aug 15, 2018 6:58 pm ]
Post subject:  Re: 30cal B51

rsterne wrote:
If you haven't seen it, I did a .22 cal that hit over 50 FPE....


Yup I sure did and now she's mine :wink:

Author:  Voltar1 [ Sat Aug 25, 2018 10:59 pm ]
Post subject:  Re: 30cal B51

Pics

Attachments:
616A8029-8AF5-456B-9AF4-8180B00F8B2D.jpeg
616A8029-8AF5-456B-9AF4-8180B00F8B2D.jpeg [ 1.38 MiB | Viewed 752 times ]

Author:  rsterne [ Sat Aug 25, 2018 11:20 pm ]
Post subject:  Re: 30cal B51

VERY nice, Walter.... lockup looks good and beefy, too.... "J" slot to retract the bolt?....

Bob

Author:  Voltar1 [ Sat Aug 25, 2018 11:26 pm ]
Post subject:  Re: 30cal B51

You got it Bob
Probeless bolt for uninhibited flow. As this gun will likely see pellets and bullets i figure seating at bore diameter will be the same as well
Thanks eh

Author:  rsterne [ Sun Aug 26, 2018 11:44 am ]
Post subject:  Re: 30cal B51

Love those "J" slots, use them in all my high-powered designs, combined with a probeless (flat nosed) bolt.... If you want adjustable power, you can use a rod that protrudes into the short slot, adjustable from the back with a SHCS like this.... You can just see the pin in the slot with the SHCS in line with it on the back of the receiver.... Screw it in and it restricts how far back the bolt can retract....

Image

When the bolt is not retracted fully, it obstructs part of the barrel port, resulting in the ability to dial down the velocity.... This gun had 9 turns of adjustment, although effectively it shot the same velocity at 7 turns out as at 9 turns.... With it all the way in, the bolt was in the loading position, and the only air providing the shot was leaking around the sides of the bolt nose.... dialing the velocity down to about 400 fps....

Image

This is particularly useful if you want to shoot pellets and bullets from the same gun, without having to completely retune it.... For instance, with the above PCP tuned to shoot the 34 gr. Beasts at 950 fps at 7 turns.... at just under 4 turns you would get the same velocity with the 27 gr. BBTs.... and at 2 turns it would still be shooting 950 fps with the 18 gr. Heavies.... It looks like you should have enough width in your receiver to do that?....
Bob

Author:  Voltar1 [ Sun Aug 26, 2018 2:06 pm ]
Post subject:  Re: 30cal B51

Very cool Bob!!

I like that setup and will check this one it is 0.950 wide with 0.312 bolt so could easily use a #10 screw with a 0.156 pin.
Having trouble finding time to shoot esp over a chrony. When work had me out in the mountains everyday it was definitely easier lol
Keep up the good work Bob, hankering to see more from you.
Walter

Author:  rsterne [ Sun Aug 26, 2018 4:51 pm ]
Post subject:  Re: 30cal B51

I'm sure an 8-32 SHCS with a 1/8" steel pin would be plenty strong.... but if you have room for a 10-32 then why not.... 8)

Glad to see you back here for sure....

Bob

Author:  Cadeau [ Sun Aug 26, 2018 6:48 pm ]
Post subject:  Re: 30cal B51

So Walter, what is the chrony numbers on this gun ? Looks good. Glad to see you post again. You and Rsterne need to get together and build and patent a high powered Canadian made airgun. You's have the knowledge. I'de be honoured if you called it the Bryan gun.

Author:  Voltar1 [ Mon Aug 27, 2018 12:29 am ]
Post subject:  Re: 30cal B51

Thank you Bob and Bryan for the welcome back. Am happy to be here for sure!
I need to get a baseline set of numbers from this setup. 2700ish is giving 860 with 46gr FX pellets.
Hope to find time to shoot a full string asap..
Cheers

Author:  Castle02 [ Mon Aug 27, 2018 8:40 am ]
Post subject:  Re: 30cal B51

Hmm, a .30 cal B51! That's awesome!

Rich

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