5000 FPS Varmint round. - Page 3
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Old 12-14-2010, 12:00 AM   #21
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Couple of issues to deal with-

First- the max acceleration that can be produced by the expanding gasses from smokeless powder. C4, Semtex, or even straight RDX does not so much create expanding gasses (it does in moderation) but generates pure shock wave. I can get nearly 23,000 fps when a shaped charge of hi-vel detonates, but the matter at the front of THAT wave is no longer solid- it is plasma.

Second- the rotational speed of the bullet will tend to spin it apart. This is part of the reason that hypervelocity tank cannon are smoothbore. You might handle this through use of a solid copper or bronze bullet, AND a very slow rate of twist- but- dependng on caliber- may not be enuff to stabilize the bullet. You might also consider a lighter bullet that can be accelerated faster- range will be shorter- but some of the aluminum alloys may be up to it.

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Old 12-14-2010, 12:09 AM   #22
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C3 kind of what I was thinking. If we could get the bullet to not twist it would be better as then we would not have to worry about spinning bullets apart.

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Old 12-14-2010, 12:30 AM   #23
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22/284, if you use a 30 inch bbl. and a 15grain bullet, you can push it to over6585 max. you would be better off using a 378 Weatherby case necked to 22 you can push a 50 gr. bullet to 4600fps no doubt that a 40 grainer would be streking along fasrer rhan that.

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Old 12-14-2010, 12:54 AM   #24
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Default 5000 fps

the .22 cheetah is about as fast as todays technology can push a bullet ...given real world scenerio....propellants,cases ,bullets , rifles etc ....but there is research going on with rail guns and electromagnetic pulse that the military skunk-works is working on for warfare .....tanks with these guns shooting specialized vulcan sabot rounds with little no blast ...or recoil .. cool

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Old 12-14-2010, 12:59 AM   #25
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You have named the game, tango....my research has started.

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Old 12-14-2010, 01:10 AM   #26
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Originally Posted by cpttango30 View Post
The thing I worry about is presure. The faster you push something the more pressure it takes.

So Pressure is a big deal I think we need to address.
Yes and no.

Of greater concern is how long that pressure is pushing the bullet.

To oversimplify things and use psudo-math (I am not up to the exercise to do it all right now.

If you have 40,000 PSI behind bullet X for 16in i will have speed of 2500 fps
If you change the barrel length to 20in it will 3000 fps.
At 26in it will be 4000 fps.

However, the longer the barrel gets, the moer time the bullet will stay in the barrel and longer the pressure will need to be maintained. This can be accomplised with slower buring powders.

However, care must also be taken that the powder is not too slow burning. If it burns too slow and has a relative gentle pressure curve, it may not be able to provide enough of a kick to swage the bullet in the rifled portion of barrel after it leaves the case. If it does get "stuck", even for a split second, it will cause a signficant pressure rise. (Static friction required much more force to overcome than dynamic friction does.)

There are a lot of variables that all play together and can be very diffictult to model. Sometimes the only way to model and determine the actual properties to by empirical analysis with a strain guage on the barrel, a chonograph and case, bullet, chamber, round, etc inspection.

As someone else above also said, be warry of the bullet flying apart. The exact rotational speed that this will happen at is entirely dependant on the composition of the bullet itself. Special bullets do not need to be used, though. A slower rate of twist will do the trick, and likely help keep pressure down as well. [With a 1 in 10 twist, a bullet at 2500 fps will rotate at 180000
RPM. If the you jump that up to 5000 fps, and change the rifling to 1 in 20, the RPM will remain the same.]

In theory, you could have an VERY long barrel and accerate a .17 bullet to escape velocities as long as you have a consistant source of pressure over the time the bullet is in the barrel.


Jason
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Old 12-14-2010, 01:26 AM   #27
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I want a cartridge that will put a bullet to 5000 FPS. Can it be done?
Something just not right here. You been drinking? Or just having some fun?
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Old 12-14-2010, 01:48 AM   #28
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Just talking and having some fun MRM.....

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Old 12-14-2010, 02:03 AM   #29
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Just talking and having some fun MRM.....
Good your having some fun. You had me worried for a second.
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Old 12-14-2010, 02:25 AM   #30
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Quote:
Originally Posted by cpttango30 View Post
The thing I worry about is presure. The faster you push something the more pressure it takes.

So Pressure is a big deal I think we need to address.
Eat more fiber and drink more water. Stop trying to force it out
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