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Deleted member 46119
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The part I'm trying to understand is a long range bullet goes from 0 to over 200,000 rpm instantly.
Shouldn't a gain twist have an effect?
Shouldn't a gain twist have an effect?
Bartlein gain twist barrel
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shortgrass
Well-Known Member
Is that because those "major bench rest competitors" are consistantly "excellent shooters/above average shots", or because of the barrel? Could they have done any better or any worse using a 5R or conventionally rifled barrel? There is no way of knowing. I do know that "practice makes perfect" and BR shooters send many more deliberate rounds toward the target than most who shoulder a rifle. Equipment can't take the place of skills that are lacking.
J E Custom
Well-Known Member
In my way of thinking, for a gain twist barrel to be effective it would have to start out at a greatly
reduced twist rate and end up at the desired twist and that would mean a lot of engraving on the bullet. I don't see any advantage in just gaining .5 twist in rifling because the bullet still has to start rotating at a very high rate. Ideally it would not start rotating at all at first and then as it traveled down the barrel increase the rotation as it increased speed to the desired twist.
I have had the problem with jacket shedding in the past in very high velocity cartridges and the bonded and mono bullets solved this, so the need for gain twist barrels diminished for me but I still have an interest in a way to improve any barrel performance.
Another thing. We /I like to think that bench rest quality is the goal for us but they are not high velocity and heavy weight bullet shooters like we are and there priorities are different in most cases so we are very hard on bullets because of the ranges and needs for Ballistics.
I am by no means an expert on this but I try to analyze every problem and apply common sense
to come to a conclusion and most of the time it works for me. (Not every time).
I still believe that the shooter has the most effect on accuracy and that most well made rifles will out shoot there owners. I have a few that will out shoot me, but I still keep trying to improve them and always will.
It is a interesting topic and I would also like to hear more opinions and theories on gain twist rifling.
J E CUSTOM
reduced twist rate and end up at the desired twist and that would mean a lot of engraving on the bullet. I don't see any advantage in just gaining .5 twist in rifling because the bullet still has to start rotating at a very high rate. Ideally it would not start rotating at all at first and then as it traveled down the barrel increase the rotation as it increased speed to the desired twist.
I have had the problem with jacket shedding in the past in very high velocity cartridges and the bonded and mono bullets solved this, so the need for gain twist barrels diminished for me but I still have an interest in a way to improve any barrel performance.
Another thing. We /I like to think that bench rest quality is the goal for us but they are not high velocity and heavy weight bullet shooters like we are and there priorities are different in most cases so we are very hard on bullets because of the ranges and needs for Ballistics.
I am by no means an expert on this but I try to analyze every problem and apply common sense
to come to a conclusion and most of the time it works for me. (Not every time).
I still believe that the shooter has the most effect on accuracy and that most well made rifles will out shoot there owners. I have a few that will out shoot me, but I still keep trying to improve them and always will.
It is a interesting topic and I would also like to hear more opinions and theories on gain twist rifling.
J E CUSTOM
The advantage comes from the bullet being continuously engraved by the lands as it goes thru the barrel. This is supposed to reduce gas leakage.
I have a gain twist by Ron Smith. It's a 1:16-1:8. It's for my 6.5 Sherman Shortmag. I've just broken in The barrel and am now getting ready to start load developement. I'm gonna crony speeds with a magnetospeed and compare them to others who have the 6.5 SS with their same loads. See if velocity as any change. I got this barrel for the theoretical lower initial pressure spike to help extend barrel life. I was gonna just go with a fairly light gain, but the barrel maker said he has had great success with the heavy gain twist.
Its not the vel of the bullet or its RPMs in the barrel that is the issue but the force behind the bullet itself forcing it to be engraved. By starting with the slowest twist rate at the throat you where the highest pressure and thus force against the bullet. This is also where the bullet is initially being engraved thus its the point of maximum stress on the jacket. As the bullet travels down it is only very marginally having new displaced jacket material by what is actually a very small increase in angle which based on reported accuracy capable of these barrels is not negatively hurting it. You also do get the benefit of possible better seal etc. that has been mentioned.
Proof of the decreased stress on the jackets can be seen where the gain twist are able to run vel that barrels with straight twist of the ending twist rate bullets were coming apart.
Do not forget that many of the best barrels manf have added a small amount of increase in twist and tighten up as they reach the muzzle. Rock as an example has been doing this for a very long time. This is just a to a larger degree.
Personally I think the limit for conventional setups is about a 1" gain.
kiwikid
Well-Known Member
The 6.5x52mm Mannlicher Carcano is the only commercially manufacturered rifle that had a gain twist barrel that I know of. The cartridge dates back to 1891. The barrel started at 1:19.25" and increased to 1: 8.25". I have never found the reason why.
nicholasjohn
Well-Known Member
Mateo,
Now that you've had this barrel for a while, how is the gain-twist rifling working out ? I have been interested in this concept for a long time, but have not done anything with it. Also, you mentioned getting the barrel from a barrel maker named Ron Smith. What is the name of his barrel-making company ? Do you have a phone number or an internet address ? Thanks.
Nick
Muddyboots
Well-Known Member
- So will there be a newly developed progressive burn powder that can take advantage of the gain twist change?
- How does a gain twist barrel affect progressive pressure in a barrel?
- Generally, has there been any study to reflect what types of powders would be most efficient in a gain twist barrel?
- Does a gain twist barrel allow you to shoot bullets that ordinarily wouldn't stabilize in the initial barrel twist?
elkaholic
Well-Known Member
I don't know about powders but I would think it would allow for slightly faster burn rates. As far as stability though, it would be whatever the twist was at the muzzle.
Left Hand Dave
Well-Known Member
I know it is not a rifle but for what it's worth S&W uses a gain twist on there 460 XVR revolvers. The twist starts off at 1 turn in 100 inches and ends at 1 turn in 20 inches. I think they very the depth too but not sure about that. I have been considering a gain twist for a .264 Win Mag build I would like to set up for 150 and 156 weight bullets. Just not sure. I was worried a 1-7 might damage bullets.
TXAoudadKlr
Well-Known Member
As far as rifle torque perhaps a left hand twist would be better with the rifle torquing to you instead of away.
