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 Post subject: Diablo/Boat tail pellet.
PostPosted: Fri Oct 28, 2016 10:48 am 
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Joined: Mon Aug 24, 2015 4:56 pm
Posts: 462
Location: Tecumseh, Ontario in South Western Ontario
If the BC of a pellet is the key to range and accuracy then this might be a better design.
It has the three most needed components to stay stable. It's heavier at the front then the back. It still has more drag at the back then the front but not as much as the regular diablo. The skirt still engages the rifling for the twist it needs.
The improved aerodynamics include a parabolic dome at the front. The waist narrows less to reduce drag behind the head but does not contact the barrel lands for reduced friction. The end of the skirt turns back inward like a boat tail to reduce drag.
As usual I have no means of making and testing the pellet it's just a thought for discussion.


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Diablo Boat tail pellet.png
Diablo Boat tail pellet.png [ 4.39 KiB | Viewed 920 times ]

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PostPosted: Fri Oct 28, 2016 6:49 pm 
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Joined: Wed Jan 05, 2011 12:35 pm
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Location: P.G. B.C.
Shows promise for larger calibres, but HP's or HB's are a pain to cast.

Solid varieties are not only easier to cast, but have higher BC's.

The hollow base is not necessary as driving bands take care of sealing air and the grooves reduce drag in the bore.

The 51gr. variety of Bob's if a Round Nose, perhaps 52 to 55gr. (as long as the standard 25 cal. rifling twists will stabilize it over longer ranges), would be less effective for hunting small game, but even more effective for longer range shooting due to the RN having a higher BC and the FN. The RN would potentially have greater penetration than the FN.

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PostPosted: Fri Oct 28, 2016 9:17 pm 
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Joined: Sat Nov 03, 2007 4:19 pm
Posts: 8989
Location: Coalmont BC
The hollow base and relatively thin skirt will cause significant obturation (expansion) under pressure.... My guess is that a fired pellet would no longer have any boattail, the back portion of the pellet would look the same as any other fired pellet, with a parallel section at groove diameter, with the rifling clearly impressed on it.... How long the parallel section is would depend on the air pressure and the thickness of the skirt.... Just my thoughts....

Bob

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PostPosted: Sat Oct 29, 2016 4:01 am 
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Joined: Mon Aug 24, 2015 4:56 pm
Posts: 462
Location: Tecumseh, Ontario in South Western Ontario
At first I also thought the boat tail would expand to the bore diameter. However once chambered the skirt will bend inward to fit the bore and there will be HPA present above and below the boat tail when fired so there would be no reason for it to expand. But yea, unless the skirt seals immediately it would be useless. The boat tail could be make thicker but who knows without an actual trial.
For discussion sake if it did maintain it's shape and with that wide waist to raise it's SD it should have a greatly improved BC IMO over the standard diablo pellet.


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Chambered.png
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