.250 cal Bob's Boattails

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rsterne

Post subject: .250 cal Bob's Boattails

Posted: Fri Jun 06, 2014 6:32 pm

Joined: Sat Nov 03, 2007 4:19 pm
Posts: 9518
Location: Coalmont BC

First results at 35 yards with my Disco Double.... Velocity was 870 fps.... The 50.6 gr. Bob's Boattails were the upper left target.... The others were 4 variations of the RCBS 50 gr. RN.... Middle column was a 46.4 gr. Hollowpoint version and the right column was the 52.9 gr. Round Nose solid, in various combinations of sized, different alloys.... The BBTs are obviously way more accurate....

I then sighted the gun in with the BBTs at 50 yards and did a preliminary BC using the POI at 75 yards and 100 yards, and it worked out to 0.110.... That's not a high as the calculated value of 0.160, but about 3 times better than JSB Kings at about 0.036....

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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rrdstarr

Post subject: Re: .250 cal Bob's Boattails

Posted: Fri Jun 06, 2014 7:51 pm

Joined: Sun Jul 15, 2012 10:49 am
Posts: 6030
Location: Victoria, BC and Clarkston, WA

Where did we get the mold from Bob?

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-Rick

Brocock Concept .22
3 Crosman MK 1 pistol .22

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rsterne

Post subject: Re: .250 cal Bob's Boattails

Posted: Fri Jun 06, 2014 10:51 pm

Joined: Sat Nov 03, 2007 4:19 pm
Posts: 9518
Location: Coalmont BC

The molds are made by Veral Smith at LBT.... The mold number is #25-52-BST.... and you can specify the diameter and alloy, or send Veral a slug of your chamber.... He can also make the bullet longer and heavier in a .257 cal but going over 2 calibers long (63 gr.) will require a twist faster than 14" which is what I was using today.... I was running a 25" long TJ's .25 ACP liner.... for those of you who haven't seen the design, here it is....

and here is a pic of the bullet as cast....

Bob

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Whitewolf

Post subject: Re: .250 cal Bob's Boattails

Posted: Sat Jun 07, 2014 12:41 am

Joined: Thu Feb 02, 2006 11:35 pm
Posts: 3099
Location: Alberta Canada

Actually wondering here Bob as to such difference upon the co eficient upon them. Any thoughts to reasoning?

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May the cry of the pack be with you upon your hunt

Whitewolf

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rsterne

Post subject: Re: .250 cal Bob's Boattails

Posted: Sat Jun 07, 2014 10:28 am

Joined: Sat Nov 03, 2007 4:19 pm
Posts: 9518
Location: Coalmont BC

Could be two possible reasons or a combination.... the software may have overpredicted the BC, and I'm not a big fan of using POI to determine the BC because of the difficulty in measuring an accurate POI for a group.... I far prefer using a Chrony for downrange measurements, but that will happen eventually....Still a threefold improvement over the most accurate pellet we have today ain't too shabby.... That translates directly into one third of the wind drift at the same velocity....

Bob

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