Shoulder angle

[TonyR]

+1, Laurie. I have seen the same thing when I compare my 7X64 Brenneke to my 284 Shehane. In fact, the 7X64 has been the most efficient way to get to 2900 fps with a 180 I have seen, although a sample of only one so far.

 

[Steve Blair]

One small correction, Laurie. Otherwise, I agree. The .300 WSM has a 35° shoulder.

 

[wboggs]

Weatherby used a lot of "freebore" and loaded to 70-71k pressures. Ads gave a 180gr. 3400fps in his Mauser action .300, almost 500fps faster than the long range .300 H&H. My uncle had one but there was no way to measure velocity. Brass was unusable after firing so we made it out of WW .300 H&H.
There are some custom makers today that claim their radical shoulder angle gives a velocity boost. I would like them to submit their arguments to the expertise of this forum's members.

 

[Laurie]

One small correction, Laurie. Otherwise, I agree. The .300 WSM has a 35° shoulder.

Thanks Steve.

Even bigger difference, then!

For other viewers of the topic, I should stress that when I was giving my opinions on the case shape effects on 'performance', that was solely in internal ballistics terms, ie the MVs and MEs that can be produced. There are all sorts of views and personal preferences so far as how different forms work out for fairly similar capacity / performance designs. I do think though as a purely personal opinion that longer 'traditional' shapes have been written off a bit too quickly by some. As examples, I'm intrigued to see the rise in popularity of the old .280 Rem in F/O on your side of the Atlantic (never been very popular in the UK even as a sporting cartridge). The very similar shape and performance 7X64 as mentioned by Tony has oddly enough received a few mentions on UK forums too recently, although again it's never been wildly popular in the British Isles even though the long-gone Parker-Hale and BSA companies manufactured lots of rifles chambered for it for export to continental Europe.

Against that, the cartridge I've been least impressed by in recent years was the .243WSSM, a good idea taken to a faddish extreme in my view. Got to be careful though what I say - there are plenty of WSSM enthusiasts on this forum!

 

[Laurie]

Weatherby used a lot of "freebore" and loaded to 70-71k pressures. Ads gave a 180gr. 3400fps in his Mauser action .300, almost 500fps faster than the long range .300 H&H. My uncle had one but there was no way to measure velocity. Brass was unusable after firing so we made it out of WW .300 H&H.
There are some custom makers today that claim their radical shoulder angle gives a velocity boost. I would like them to submit their arguments to the expertise of this forum's members.

Mik MacPherson wrote an article on this subject under the heading of Wildcats, or maybe over bore capacity cartridges, some years back for one of the early editions of Cartridges of the World after Frank Barnes died. I've tried to find the edition and the article several times over the years, but never turned it up. (Maybe it wasn't in COTW and my memory is playing tricks - again!) Mik McP noted that manufacturers regularly get wildcat inventors turning up claiming that some specific and very special shoulder angle quoted to half a degree makes the cartridge so much more 'efficient' that it'll produce X or Y hundred more fps MV than a similar factory design. If they bother to look into it, it usually does produce high MVs, but solely because it's been loaded to the gills and 80,000 psi pressures on the load development process that sees powder charges increased until the primer leaks or blows, then dropped by half a grain or similar small amount to make the load 'safe'

This was the article that had a report on some huge case necked down to 0.22 and where the test rifle lasted less than 10 rounds - a joke round that was called something like the .22 Earsplittencrackenboomer!

Incidentally, with Weatherby pressures that you mention gave the brass a single firing life, you've got to wonder how his 'African' cartridges got on in a really hot day in Kenya or suchlike. Terry Wieland argues strongly in his books on the subject that the great early British dangerous game rounds that used much roomier cases than the powder charges required and ran at modest pressures had a great deal of common sense behind them, and he's rather critical of many more modern US high pressure and compressed loads 'dangerous game' cartridges. (I've no personal experience at all of either Africa or dangerous game, but the ballistics aspects of these big cartridges and the lovely rifles have always interested me.)

 

[wboggs]

Laurie Rumor has it that R. WBY. experimented with a .378 necked to .224. Probably no old timer around to verify it. I have seen his 1950's rounds in action and they were HOT. My uncle put a 180 Hornady into a moose's shoulder at about 150yds and he stood there and looked at us.
One shot from my old .30-06 with a Rem. 220 HP CoreLokt and he was down. The Wby round didn't even penetrate the shoulder and was fragmented to pieces so we know it was really moving.

 

[dkhunt14]

I think he used a sabot in the 378-22 round. The army hired him to see if he could get 5000 fps out of a shoulder fired rifle and he did with a 22 caliber sabot in the 378 case. Laurie I think the bigger bore size and long freebore helped them African rounds when it got hot. Matt

 

[wboggs]

A smooth bore sabot should generate the velocity. It is my impression that velocity is theoretically limited by the velocity of the expanding gas, friction, etc.
There are some conventional rounds that will exceed 4600fps using a .224 30 gr bullet.

 

[CatShooter]

A smooth bore sabot should generate the velocity. It is my impression that velocity is theoretically limited by the velocity of the expanding gas, friction, etc.
There are some conventional rounds that will exceed 4600fps using a .224 30 gr bullet.

Homer Powley and Robert Hutton used Remington 19 GR. Sintered Iron Bullets in a 22-284 and got 6585 FPS using 50 Gr. 4227.

 

[Grimstod]

Ben did you say those bullets were Iron? I guess there would be less friction but it would have to be murder on the barrel.

 

[Heman]

The round your talking about was a 378 necked down to a .22. This is what was known as the .22 Eargesplitten Loudenboomber and P.O. Ackley was the creator. Here is a link with a picture.

http://www.everydaynodaysoff.com/2010/05/10/22-eargesplitten-loudenboomer/

 

[Syncrowave]

The round your talking about was a 378 necked down to a .22. This is what was known as the .22 Eargesplitten Loudenboomber and P.O. Ackley was the creator. Here is a link with a picture.

http://www.everydaynodaysoff.com/2010/05/10/22-eargesplitten-loudenboomer/

LOL, that's just nuts!

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[dkhunt14]

Roy Weatherby was contracted by the military to make a shoulder fired round that exceeded 5000 fps. He did it with a 22 cal sabot in the 378 case. He did it in the 1950's. Matt

 

[CatShooter]

"Ben did you say those bullets were Iron? I guess there would be less friction but it would have to be murder on the barrel.

They were not chosen for friction considerations - they were chosen because they were strong enough to stay together at 6,585 fps.

Barrel wear was not an issue. The sintered iron bullets were from Remington 22 short gallery loads, used in country fair shooting galleries - those rifles were good for 100,000 rounds.

The powder burned up the barrel long before the any bullet could do damage.

 

[wboggs]

I would like to ask CatShooter the theoretical limits on the velocity of the expanding gases using conventional case/powder components. It seems to me that any projectile velocity has to be less than this.

 

[CatShooter]

I would like to ask CatShooter the theoretical limits on the velocity of the expanding gases using conventional case/powder components. It seems to me that any projectile velocity has to be less than this.

I am not sure what you mean by, "It seems to me that any projectile velocity has to be less than this.".

But the problem with powder propelled objects is that as the charge to object ratio gets larger and larger, the energy added with each addition of powder, is used to push out the very gas it makes - 90 grains of powder makes 90 grains of gas. It takes the same energy to push 90 grains of gas out, as it does to push a 90 grain bullet out.

Somewhere around 7,000 fps is the limit for direct powder/projectile driven guns, and at that point, the guns are ridiculous laboratory toys.

The next step in velocity is two stage guns, where powder is used to drive a piston, which compresses a large quality of helium gas (which is very light), and then the Helium drives a projectile - velocities over 25,000 fps have been reached with guns of this type.

 

[dkhunt14]

Supposedly Charles McDonald ran a 30 grain Berger 5239 out of a 6BR improved case. It was called a 224 McDonald. There was another guy that went over 6000 with a 22-284. Matt

 

[CanusLatransSnpr]

You might Google the term "convergence angle" to get the low down on advantages of keeping the convergence of the case shoulder angles within the cartridge case neck. The theory has been around for a long time.

Danny Biggs

I have seen this term used in building tuned pipes for 2-stroke motors but, never in the cartridge world. The convergence angle in a tuned pipe scenario has to do with harmonics and the scavenging of fuel/air that leaks inside the pipe during that small window the exhaust port is open. It really is an unfair comparison though because there is a divergent angle in a tuned pipe, which isn't present in a rifle cartridge, that helps in the efficiency and harmonics!

I can see where you are going with this though because it is tough to funnel 10 lbs. of s#$t into a 5 lb. sack!

Mike

 

[CatShooter]

I can see where you are going with this though because it is tough to funnel 10 lbs. of s#$t into a 5 lb. sack!

Mike

Not when there is 55,000 psi shoving the s#$t into the funnel.

 

[wboggs]

CatShooter Thanks for the explanation of velocity limits for conventional cartridges. One other question, the temperature of the gases in the barrel?
Thanks
Bill