Looking for a barrel blank. (491-492/.500) to fire .500 ammo. Will require a high twist rate. target is 1:10. I am striking out and all I can find is 1:19 twist. Looking for a list of bulk blank makers and I guess if I strike out there, I need to consider a custom twist ($$$). Not looking forward to that.
Gunsmithing .500 barrel blank, 1:10 twist?
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Re: .500 barrel blank, 1:10 twist?
Pac-Nor offers a 1:9" twist 0.500" groove diameter barrel.
I would assume that the bore was around 0.492", but give them a call...
http://www.pac-nor.com/barrels/
Otherwise, any of the cut rifle makers should be able to do it.
Pac-Nor offers a 1:9" twist 0.500" groove diameter barrel.
I would assume that the bore was around 0.492", but give them a call...
http://www.pac-nor.com/barrels/
Otherwise, any of the cut rifle makers should be able to do it.
Re: .500 barrel blank, 1:10 twist?
Thanks. I notice they only offer the 9" in a 3 groove. With a .500, I might be a bit concerned with the 3 groove if I push lighter, faster rounds out of it. Any thoughts on that? I thought 6 groove was pretty standard for big bores.
Thanks. I notice they only offer the 9" in a 3 groove. With a .500, I might be a bit concerned with the 3 groove if I push lighter, faster rounds out of it. Any thoughts on that? I thought 6 groove was pretty standard for big bores.
Re: .500 barrel blank, 1:10 twist?
What bullet are you looking to launch with it? My factory NEF 500SW stabilizes a cast 750gr FP at 900fps in -800' DA and it is surprisingly accurate too.
Depending on what you're looking to do with it you might not actually need to double the twist rate.
What bullet are you looking to launch with it? My factory NEF 500SW stabilizes a cast 750gr FP at 900fps in -800' DA and it is surprisingly accurate too.
Depending on what you're looking to do with it you might not actually need to double the twist rate.
Re: .500 barrel blank, 1:10 twist?
My goal is to be able to stabilize over 1000gr custom mad slugs. Considering lead and brass, brass will obviously be longer and take more twist to stabilize. I want the longest effective range possible from the rifle. The 1:9 barrel from above has my attention. It is really higher twist than I prefer so still looking a bit. A high twist and well designed subsonic slug should fly very well though with radical doping as might be typical of a 1000M shot from a high power rifle.
All the calcs I am running show a worst case of about 1:10 twist. Best case is about a 1:14. I have read where several people indicate heavy slugs do not fly well but I think there is quite a disconnect of slug vs twist. At subsonic speeds, I should be able to twist a bit higher without concern of over driving the rifling.
My goal is to be able to stabilize over 1000gr custom mad slugs. Considering lead and brass, brass will obviously be longer and take more twist to stabilize. I want the longest effective range possible from the rifle. The 1:9 barrel from above has my attention. It is really higher twist than I prefer so still looking a bit. A high twist and well designed subsonic slug should fly very well though with radical doping as might be typical of a 1000M shot from a high power rifle.
All the calcs I am running show a worst case of about 1:10 twist. Best case is about a 1:14. I have read where several people indicate heavy slugs do not fly well but I think there is quite a disconnect of slug vs twist. At subsonic speeds, I should be able to twist a bit higher without concern of over driving the rifling.
Re: .500 barrel blank, 1:10 twist?
What are you using to calculate stability for a given twist rate? Miller's approach makes some general assumptions about empirially derived values that don't work well at <2000fps launch velocities.
The shape that Miller assumes is also more like a spitzer/boat tail than a normal subsonic-designed rifle bullet and may cause issues there.
I'd like to see what you come up iwth, perhaps we can chat off-line regarding this project.
What are you using to calculate stability for a given twist rate? Miller's approach makes some general assumptions about empirially derived values that don't work well at <2000fps launch velocities.
The shape that Miller assumes is also more like a spitzer/boat tail than a normal subsonic-designed rifle bullet and may cause issues there.
I'd like to see what you come up iwth, perhaps we can chat off-line regarding this project.
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