So with always being the thiking kind and my ming gears are always turning. I got to thinking...

I wouldnt mind developing rifle cartridge I could use on a wide assortment of game but still be able to engage small varmints at long distances.

my thoughts are something 30-06, or 300 Win Mag brass. Brass necked down to a 25 caliber bullet.

This would give you the choice of loading a sorta light weight bullet at 80 grains and achieve quite a bit of speed. Or load it with a heavier bullet and take on medium sized American game.

Would 5000fps be too much to ask out of something like that? Or would I have to drop all the way to something like a 22 caliber? I would prefer to stay above the .243 caliber and still reach the very high rate of speed.

quote:

Would 5000fps be too much to ask out of something like that? Or would I have to drop all the way to something like a 22 caliber? I would prefer to stay above the .243 caliber and still reach the very high rate of speed

Won't happen. You are hard pressed to get a light 22 or 243 above 4000 much less 5000.

Take a 257 85gr in a 30" barrel with 100 gr capcity behind it and at 63,000 your might break 4000. Same deal with a 55gr 243 bullet with a 100gr case and you can reach 4350 if you can get 117% density. More like 4250.

I seem to remember people taking 50cal brass and necking it down and found all they did was burn powder.

Sounds to me like trying to achieve celerity-- and we all know how much fuel that would require...

Hrmmm, well I dont know much about these things. But I love small caliber FAST rounds. I love shooting my 204 at very small targets out past 200 yrds. I was just braing storming for something that could out run my 204 and carry more energy.

If you want a hot 204 here you go.

5 mm/35 SMc is a high performance 5 mm (.20 caliber) cartridge. Designed by Michael "Mic" McPherson and Byrom Smalley[1] and like all of their other designs carries the "SMc" moniker.

""" Description
SMc cartridges were developed in an attempt to produce an efficient cartridge combining low recoil, low heat, and high velocity[2]. The 5 mm/35 SMc has produced velocities in excess of 1463 m/s (4800 ft/s) (30 grain (1.9 g) molybdenum disulfide-plated Berger bullet from a 28 inch (711 mm) Pac-Nor barrel), far higher than its commercial counterpart the .204 Ruger."""

http://en.wikipedia.org/wiki/5mm/35_SMc

If you do the looking you will find that items like the 22-06, 22-284 220Wby for the most part add very little over the 220Swift 22-250AI, 22-243, 224TTH or 224 Clark.

[

Yeah thats nice and fast and all, and pretty cool to boot.

But my idea I would like to have either a .243 or .257 caliber to be able to shoot that fast with 80gr or lighter bullets. Then be able to switch to 110+ grain bullets and still carry 3500+ fps and hunt Whitetail with it.

quote:

But my idea I would like to have either a .243 or .257 caliber to be able to shoot that fast with 80gr or lighter bullets. Then be able to switch to 110+ grain bullets and still carry 3500+ fps and hunt Whitetail with it.

Well if you lower your sights a touch go buy a 257Wby. In a 26" a 82gr loaded to 65,000 gets you 3980 per QL. If I increase the capaity to 110grs (30% increase) the velocity is only 4054. So for a 23% increase in powder charge a 30% increase in capacity you get a 1.8% increase in velocity. Not to mention how short the barrel life would be.

The 257Wby can then get you a 115 in the 3450 to 3500fps range.

257 weatherby can't make 4K, and its a barrel burners.

The work has already been done:

http://www.lazzeroni.com/ct_lacart.htm

quote:

257 weatherby can't make 4K, and its a barrel burners.

I agree with you QL would only allow me to 3980 with taking everything to the max. Real world more like 3725-3800.

Just being curious looking at the velocity Lazzeroni claims compared to max 65,000 velocities from QL in a 27" like their test. QL comes up about 100-150fps slower on all counts.

Ok then, so here is a question.

What type of brass would it take to propel a .243 bullet to 4500+fps? Barrel life is not of concern...

Or is it an impossible task to prepel that large of a bullet that fast?

I have chrono'd my 204 with factory loaded ammo 32gr hornady. It claims 4225 on the box, but the best I seen was 4105.

Nearly impossible using that small of cases.
I got a 300gr bullet in a 12ga sabot in the
12ga FH to 3900 at about 40k psi in Savage
12ga. Now we put a 150gr in sabot and run
pressure to 50k and we would get 5 grand,
Guys have necked full length 20mm to 50cal and
got lighter(647gr) 50cal bullets to 5000 fps,
at high pressures. One in middle..ED

Ask me about my 22 EargeSplitten-LoudenBoomer* some time...

Rich

* it's a 22-378 Wby with a 35-degree Ackley type shoulder. 60gr Nosler Solid bases bullets pushing 5400fps.

Brando
The 408 Chey-Tac would be your best bet. It's a version of the 505 Gibbs, with a strengthened case head to withstand 65,000 psi pressures. The real problem is finding a powder slow enough to fill that case and not exceed 65,000 psi. I don't know if you can get the 20mm cannon powder as surplus or not; but it would be your best bet. Barrel life would be measured not in hundreds of shots, or even dozens of shots, but in single shots so the practicality of your wildcat has to be a big question mark.

Thought I understood from some place that modern powders will only expand at a maximum rate of about 5,500 fps on their own, with no bullet to push. IF that is the case, then the bullet would have to be awfully light.
But I have been wrong before. . . . . .

DW, about 7900 fps is the max propellent speed

Maybe Ed can figure out how to make you a man-portable version of this:
Light Gas Gun

From Wikipedia: One particular light gas gun used by NASA uses a modified 40 mm cannon for power. The cannon uses gunpowder to propel a plastic (usually HDPE) piston down the cannon barrel, which is filled with high-pressure hydrogen gas. At the end of the cannon barrel is a conical section, leading down to the 5 mm barrel that fires the projectile. In this conical section is a stainless steel disk approximately 2 mm thick, with an "x" pattern scored into the surface in the middle. When the hydrogen develops sufficient pressure to burst the scored section of the disk, the hydrogen flows through the hole and accelerates the projectile to a velocity of 6 km/s (22,000 km/h) in a distance of about a meter.

6km/s is about 20,000fps! Should be perfect for prarie dogs.

Hey I found the answer for a 5000fps chambering. I only needed a 27" barrel and a 257Wby. Of course finding a 38gr .257 bullet might be a touch on the hard side.

Brando I think what we all are trying to say as to a 5000fps rifle you just can't really get there from here.

You have to be light for the caliber
like a 100gr aluminum bullet in a 12ga FH
sabot, You got to have cases that hold
300gr of powder or more rather than 75gr
of powder.ED

Size does matter!

27" = 3900fps



34" = 4100fps+



All else equal.

It's been done with 30 grain .224 caliber bullets in the 22-250 Ackley and 22-243 Improved.

I've seen the 50bmg guys shooting sabots with 30 cal bullets in them.
I wonder what kind of speeds they were getting?

I really dont know

John

Some of the BMG SLAP rounds hit 5000fps.

quote:

Originally posted by jpl:
Some of the BMG SLAP rounds hit 5000fps.

4000 is the advertised speed in the manual, (page 4-39)
http://www.dtic.mil/dticasd/sbir/sbir032/a044a.pdf

Cheers!
Collins

quote:

Originally posted by Phatman:
I've seen the 50bmg guys shooting sabots with 30 cal bullets in them.
I wonder what kind of speeds they were getting?

I really dont know

John

It's tough to crony those as the sabot comes apart and destroys the Chronograph. (ask me how I know) Also, the sabot spins around the bullet so accuracy isn't too good either.

quote:

Originally posted by jeffeosso:
DW, about 7900 fps is the max propellent speed

Howly crap! Where have I been?

Thanks for that tid bit. Gotta keep up you know. . . . . .

quote:

Originally posted by Collins:
It's tough to crony those as the sabot comes apart and destroys the Chronograph. (ask me how I know) Also, the sabot spins around the bullet so accuracy isn't too good either.

Could you set-up a thick piece of card board or something to keep the Sabot from hitting the Chrono? Shoot the bullet through the card board and have the paper in front of the chrono.

I was talking, quite a long talk, with the guys that developed the bimetal bore riders .. i forget the name, but they claim it frags in a light target and penerates in a hard one (which is actually against the geneva accords, but wcyd?)

they made a light as 200gr BMG bore rider, and could not get past 5000fps with granular powders.. we talked and it appears that the burn rate of some powders approaches 7900fps .. when means if you laid out 2 miles of it, a mile and half would be burnt in a second! most rifle powders go faster under pressure.. that's understandable

liquid propellents, however, can go faster still ... too fast of powder goes BOOM.. tinkle tinkle steel rain .. but liquid propelent suposedly can be made to NOT go boom.. i think he tried to tell me why, but after about 2 hours of ballastics, even *I* get bored

he SAID 7000FPS was possible with liquids and light projectiles... i don't know about all that...

I do know that when you get that overbore without it being a magentic rail gun, you are just abraiding the barrel BADLY on every shot .. and abalatting it on a rail gun, in atmosphere

I think you might be wrong... Gunpowder (smokeless) isn't an explosive by BATFE law. It deflagrates which means the burning is less than the speed of sound (M1 or about 900FPS) the thing that pushes the bullet out is the rate of gas expansion which is channeled out a small tube. I have heard, 2nd hand, that the fastest velocity possible down that tube via the pressure created is around 5000 FPS but there's a LOT of physics associated with the derivation of that number.

quote:

Originally posted by Brando:

quote:

Originally posted by Collins:
It's tough to crony those as the sabot comes apart and destroys the Chronograph. (ask me how I know) Also, the sabot spins around the bullet so accuracy isn't too good either.

Could you set-up a thick piece of card board or something to keep the Sabot from hitting the Chrono? Shoot the bullet through the card board and have the paper in front of the chrono.

Yep, I now have what looks like a pellet trap (45 degrees) with a hole for the projectile. works very well. The Sabot is still moving at 3500-4000 FPS, Cardboard wouldn't work.

For chrono I epoxy the slug in the sabot.Ed

RBCD 50BMG 200gr 30cal sabot 5900fps

Could you post a link to that? I went to their site and they show a picture but I can't find any real info on it. The fasted 50 I find is 3900 fps.

http://www.rbcd.net/50-%20BMG.html

Collins

You whant to have 5000fps...?

May have a look at Feb.Edition of PRECISION SHOOTING MAGAZIN. Theres a .223-300WSM dinig 5019fps......

Best
2RECON

I have a 28" barrel set back for 40 grain bullets. Its a Remington 700 in .220 Swift. I built it to break the 5000fps mark.


After alot of testing I found the only bullet that would stay together above 4800 fps was the Berger mef. I used once fired cases, and neck size only, and with a six inch drop tube used alot of VVN540.

The results over my ohler 34 were,

40 grain berger. 4800 fps

35 grain berger 5030 fps

30 grain berger 5240 fps

The US experimented with tapered bore after WWII. I believe they got something around 7,000fps. Of course, I lost the info. A note to the Aberdeen Provining Grounds might get you a reference.


On the other hand, AEDC has a two stage light gas gun that will shoot a 3.3 inch projectile at 23,000 FPS.

It isn't a issue of reaching 5000fps. Yes no doubt that with a 22 the right barrel, right case and LIGHT bullet you can reach 5000fps. Not an issue.

The original request was to take a 243 or 257 cal 80gr preference being a .257 and reach 5000 and then switch to a 110+ plus at 3500 for deer.

check with Thor inc. they might have and idea or three.

thor global defence.

How many shots would you expect to get from a barrel that has had bullets go through it at 5,000 fps? If it's what you want to do, so be it. Just seems to me like a way to go through lots of money in new barrels and in having them installed...