ajkellerusmc
Well-Known Member
A little more than just a little bit!Does this project make anyone else giggle just a little bit??
5,000 fps coyote rifle?
- Thread starter codyadams
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ajkellerusmc
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What is bridging?
ajkellerusmc
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Dead watermelons! That don't impress me much!
J E Custom
Well-Known Member
I see this often when using fast twist barrels. That is the reason I went with the 1 in 15 and 1 in 16. I also had the same problem with the 7mm I talked about at 3800 ft/sec. It had a 1 in 9.250 twist and Just over 3800 ft/sec all accuracy went away because of jacket shedding.
I also saw this with some 223's that had a 1 in 7 twist. I backed off on my 223 AI and used a 1 in 8 twist and this thing will out shoot me every time Not to hard But with group size hovering just under .200 thousandths, it is very consistent. Some of the guys that I know that shoot matches had went to 1 in 7 to shoot the heavier bullets and went back to 1 in 8 after a while.
In my opinion, You can go to far with fast twist and may only find one bullet that will work.
J E CUSTOM
Capt RB
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.Kirby Allen posted up a very good explanation of this phenomenon
Fiftydriver said: ↑
Basically, when X amount of powder is trying to pass through a certain diameter hole, it has a limit in how fast the powder can flow through this opening.
With a very large case capacity round with a modern, sharp shoulder angle, this becomes a problem with smaller caliber cases. Now this depends on the caliber as well as the diameter of the case powder column and the total powder volume.
What happens is when a round is ignited by the primer, the blast from the primer forces the powder in the case foward until it is stopped by the shoulder and seated bullet. Then it begins to ignite.
As the pressure inside the case increases from the rear of the case forward, it increases the pressure on the powder. Powder bridging occurs when the pressure actually locks the powder granuals together because they simply can not pass though the neck of the case and pressure increases dramatically.
In the case of my Allen Mags, the 257 and 6.5mm are the only two that so far have had this problem. The simple cure is to use Ball powder. This solves the problem simply because this powder shape can flow at MUCH higher rates through even smaller neck diameters then any stick powder.
In the 270 and larger Allen Magnums, this has not been a problem at all but I still generally use the real slow burning ball powders simply because of their lower burn temps and they are much easier on the throat of the chamber as the powder is forced through.
Hope this helps some.
Kirby Allen(50)
As everyone knows there are formulas for plugging in/arriving at BC's, bullet weights and velocities, barrel lengths and rates of twist. If you're smarter than I you can add in weather factors as well. Hornady sells stock .22-250 ammo thst does 4450 out of the box. While I'm enjoying this thread immensely and learning some things, I'm wondering st what distance your bullet has traveled before it drops through transonic speed and goes all funky, likely tumbling, losing all accuracy? Just a thought. Perhaps this isnt even relevant.
I guess since you mentioned 400 yards this isn't a factor.
codyadams
Well-Known Member
Transonic isn't really a concern with this concept, as it's sole intent is reaching scorching fast speed to have the farthest possible aim on fur distance. It will be far beyond the aim on fur distance prior to hitting transonic, this isn't what I would consider a "long range" coyote rifle, but more a "don't think about it" coyote rifle. If I wanted a "long range" coyote rifle I would do at least a 22-250 AI with an 8 twist and likely shoot the 75-88 grain eldm, and would be a 500+ yard dog gun. I have something with similar trajectory, so that isn't the point ha ha.
To reiterate, the point of this is just to reach fast speeds.
Another thought is 35 grain .224 cal mono, in one of the overbore cartridges listed, with a gain twist barrel that progresses to a 16 or 17 twist, dependent on barrel. According to a stability calculator and using dimensions from a hornady 40 grain vmax, which estimating would be similar to a 35 grain mono, at my elevation (6800 ft) a 16 twist stabilizes just fine, and a 17 twist would stabilize down to roughly 35 degrees. Below that it drops to an s.g. of 1.3, which may possibly still be sufficient, but may not. But a gain twist ending with 16 would likely stabilize, and not have much more rotational velocity than a 4000 fps load in a 12 twist, which is very doable. The issue then would be getting a bullet that doesn't have issues with shedding due to the raw speed, but again, I think a gain twist would help.
HARPERC
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Having a bullet maker in on the project is helpful.
David Urasky
Well-Known Member
Go to a 20 cal bullet. The Berger 40 grain is super slick in the air. I push 4200 FPS in my 20 tactical. SPL works great to extend barrel life and cleaning is fast. I first started using the spl in the 20 but have since grown to use it in all my guns. My 308 1000 yard target rifle shoots great with it and cleans up real fast.
I know it will slow down a bit. But it would be one for the books having somebody nail a coyote with a rifle pushing a projectile with that kind of speed.
I want to get one with a .338 275 grain RMB.
Calamity
Well-Known Member
NASA-Ames once built a pressure gun inside an evacuated pipe several hundred feet long to test the effects of micrometeorites on materials. The gun was a 243 (I believe) that fired a projectile comprised of a sabot with a BB size ball bearing inside. The sabot split upon leaving the muzzle, releasing the BB. It would be an interesting project to build a fixed barreled action that could be fired remotely, on something like a 30-06 cartridge, and develop a safe load that could be fired in a regular hunting rifle. San Diego Plastics carries graphite impregnated RULON that might work for the sabot. http://www.sdplastics.com/rulon.html
Calamity
Well-Known Member
The Ames gun developed velocities around 10,000 FPS, I believe.
Bruce Treloar
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Best 224 I have seen was a 22-250 Ackley improved 1 in 8 twist with the longest 224 Sierra projectiles in the Sierra range. The worst were those doing over 4,000 ftsec.
Why so much velocity ? I shoot a 22PPC both benchrest competition and field. I've been out hunting with guys using Swifts and 22.250's, one guy came back and had his Swft barrel changed to 22PPC on another action.
My choice would be velocity Little under 4,000 ftsec small primer case like 22 PPC or 22BR for accuracy, 53 to 54 grain projectile made on a 740 long J4 jacket , 1in 14 twist barrel.
That things going to shoot and not have all the problems you will experience using less accurate cases to achieve high velocities.
Tie an in season bitch up to a ground spike or a carcass up a tree ,sit in a good vantage point where you are set up for a mote accurate rest.
Why so much velocity ? I shoot a 22PPC both benchrest competition and field. I've been out hunting with guys using Swifts and 22.250's, one guy came back and had his Swft barrel changed to 22PPC on another action.
My choice would be velocity Little under 4,000 ftsec small primer case like 22 PPC or 22BR for accuracy, 53 to 54 grain projectile made on a 740 long J4 jacket , 1in 14 twist barrel.
That things going to shoot and not have all the problems you will experience using less accurate cases to achieve high velocities.
Tie an in season bitch up to a ground spike or a carcass up a tree ,sit in a good vantage point where you are set up for a mote accurate rest.
