let’s talk about overbore

Bear, I like my 22 BR a lot. Let me recommend however that you go with Lapua or Norma cases. The Rems I have had inconsistent necks and primer pockets. I know that most benchrestnik accuracy nuts would uniform the cases, but I'm a plug and play sort...as in plug the thing with a bullet and go play.

Hey MOUNTAINEER  >>  Speak'n of the 7mm RUM, I've got myself 1/2 talked into a nice little project for my Win. Laredo.  It's still in the planning stages right now but my but things right now are centering around a 32", 1:8 twist, staight taper, super-match grade ss barrel.  Blueprinted action (thought this was done by my last smith, but nope, nice suprise there     ...     he's not my smith any longer).  And a real heavy for caliber, bonded core .284 bullet made by a fella out of Canada that's supposed to have a BC in the .7's.  I doubt this will be ready to go for any 1K varminting this year, but by the time next rolls around, something real nice should be worked up for those extended ranges.

Added bonus, that 30+ inch barrel should take care of any over-bore issues that get folks so up in arms    .  Later.  >>  klallen

Some of you might like to try my favorite wildcat, the .17-40 Herbivore.  This is the 40mm Bofors Anti-aircraft round necked to .17 caliber.   These rifles have to be kept cased -- the barrel erodes just sitting in the safe.

To take advantage of the high velocity, I make 180-grain bullets, with a BC of over 100.  Because of the fast twist required (1 in 0.00001), I use a smoothbore barrel.  I hired some runners from norther Europe to run alongside the bullet as it goes down range and keep it pointed in the  right direction.

Yes, .17-40 Herbivore is Finn-Stabilized.

King---The .22 Eargesplitten Loudenboomer was made way back when. (P.O. Ackley wrote about it in 1964) It was made for Bob Hutton of Guns and Ammo. He was after the record vel for the .22 cal. Ackley said he got vel of 4600 with 50 gr bullet and 105 gr H570.That was starting his development. Didn't give the rifling twist. I haven't heard if he ever set a record or not.

                    Bronco

Edited by Bronco

GUN DIGEST - TWELFTH EDITION, page 50, 1958.         & nbsp;     

 "Common Sense Case Capacity" by JOHN MAYNARD

If you have access to this edition, you might take a look at this article and perhaps copy to this thread, some of what is printed.

Several cartridge sizes were necked down to 6mm, pressure was standardized at ~50,000 lbs.

The following is taken out of context, but contains some of the "meat" of the article:

What price then the necked-down milk bottle? What virtue is the supersized cartridge, for example, the 244 Holland & Holland which towers over all others in the illustration? It will old 84.8 grains of water, almost twice an little case #7, [250 Long - samchap] but does it double its velocity? It does not! It beatsm it some 10% at best. Will it, without super-pressures, produce overwhelmingly more of the desired bullet speed, give us the decided edge in flatness of trajectory and killing impact which we look for in a hunting cartridge? An edge, yes, but one derived only in consistently les and lesser degree as we pile in more and more powder-or horsepower if you will. And the birdies do say that the 3500foot-seconds which that Chrysler Building of a 244 H&H is stated to give 100 grain bullets are hard to come by at reasonable pressures, hard indeed. The truth is that for 50,000 pound pressures and 1957 powders the maximum speed for 100-grain 6mm bullets is some 3250 feet per second.

........... It's common knowledge that  added pressures mean added velocities. If and when practical cartridge brass will hold 80-100,000 pounds we will have reqal speedsters. What isn't generally known or certaintly is not generally conceeded is that as the cartridge itself gets bigger, jacking the steam up in its boiler produces less and less velocity per pound of pressure. Or one might infer the converse, that the bigger the case the more pressure rise is needed to produce a given gain.

.............. Nor are these laws limited to the 24 caliber alone. They apply to every caliber.

I am not conversant with the over-bore subject but I did find this article enlightening and I do understand this subject a little more now.

OBTW......The article is opened with this:

 The author believes the cartridge pictured is the  ultima Thule for varmit shooting-this is the 50-30--22-17 Broblilput (Registered) with a muzzle velocity of 6125 f.s. The gravity defying 25gr. full jacketed softpointbullet shoots flat for about 535 yards.

The picture of the cartridge literally looks like a launch photograph of an Apollo rocket.

To get back to this thread....It seems that not a [whole lot] has changed in velocities since 1958???

 

     

Edited by samchap

Bronco, I have a .22 Cheetah reamer. I built one for a guy several years ago. He absolutely loved it. I don't think he is shooting it much or I would have had to rechamber it long before now...............Kingpin