General discussion > Black Powder Shooting

Colerain gain twist accuracy results??

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recurve:
just finished a rifle with a gain twist 38-inch B weight barrel .50 from Mr Hoyt and at 25 yrds slightly high dead on at 50yrds and at 100yrds <with 70 grains 3f Swiss . my other.50s from Mr. Hoyt 1-56 twist 42-inch barrel, are right on at 50 but 2-inch low at 100 with the same load . Mr Hoyt said the gain twist hits harder and faster my results back that up.

Hungry Horse:
 My opinion is strictly from my observations over the years while deer hunting in California. Now I know most of our deer are a smaller variety than other areas, but they are tough. My observations tend to support the theory that fast twist barrels impart more shock than slow twist barrels.
 The real problem with trying to really pin this down is the fast twist doesn’t produce consistent results at extended range. And the slow twist requires considerably more powder to stabilize the ball. So comparisons are hard.
 Enter the gain twist. This is the best of both worlds for the hunter, hard hitting accuracy with the devastating damage of the fast twist barrel. This is the perfect balance for hunting, because most designated hunting rifles don’t get a lot of barrel wear and thats a good thing because gain twist are a bear to freshen out. Happy hunting.

Hungry Horse

yulzari:
My take on this is that the ball is accelerating up the barrel. Initially it is at a (comparatively) slow speed and can cope with a fast rate of change of the twist without stripping, soon it gets faster and, as it does so, the twist should increase at an increasingly slow rate of change. What we want is a constant rate rotation per unit of time which puts the combination under a constant stress in the grip of the rifling as it will have to meet the stress of the final twist anyway.

Thus one might postulate that a falling twist would be the best to give a constant stress with changing velocity and twist but life is too short to stuff mushrooms and a constant twist will give the bullet the same rotation and velocity as it emerges from the muzzle as gaining or falling twist rifling.

I suspect that the bullet only knows at what speed it emerges and how fast it is spinning. How it got there is immaterial to it but you are very happy with it and so that is the main thing and I wish you well with the fine beastie.

The ultimate gaining twist must be the Paradox bore and its copies. The innocent ball happily rushes up the smoothbore with no spin at all until it gets to within single figure centimetres of the muzzle and suddenly, at high speed, it is grasped by burly unkind ridges that rudely spin it up to speed all but instantly. As Emile Levasseur allegedly said of his unsophisticated crash gearbox in his pre WW1 racing car “c’est brut mais ca marche” It is crude but it works.

Good luck and good fun.

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