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My understanding is we measure barrel length from muzzle to bolt face, not from leade/start of rifling to muzzle. In keeping with the fact that ignition starts in the case and hence the case forms part of the ‘barrel’. So it seems to me that case length shouldn’t matter in this specific issue?? Of course case capacity is another matter entirely. Not sure if I’ve made my point clearly?
Greetings HandH,
Yes you made your point clearly. Most barrels are measured to the bolt face for convenience. If you think of a projectile as a rocket sitting on a ramp it might help. The rocket motor provided an amount of thrust similar to the pressure behind the projectile. thrust/ pressure is the same the rocket will accelerate at the same rate and achieve the same velocity at the same distance from the start. If we now go back to our projectile the barrel is our launch ramp and the length of travel of the projectile determines the velocity provided everything else is the same. The devil is in those last five words. With John and Charlie's test the length of the barrel to the base of projectile was the same and the velocities with some loads were near identical. With other loads they were not. In practical terms it matters little how barrels are measured as the difference in velocity is miniscule. Still something for the anal to ponder over though.
Regards Grandpamac.
Well, @zimmer if your lust is strong enough I’ve got a Sauer 375 H&H with enough ammo and components to last two lifetimes....toying with reducing battery to 416 Rigby and 9.3x62...Quote:
Originally Posted by zimmer
Greetings Zimmer,Quote:
Originally Posted by zimmer
Yes true Zimmer as we age our need for interesting rifles declines but our desire for them increases. I and likely you as well do not actually need most of the rifles in our cabinet but our declining remaining years prevents us from selling any, as they all have memories and increases the desire for more. Only the tales of the depression we heard from those who were actually there, plus a frugal outlook, prevent us from filling new cabinets with interesting but largely redundant rifles. This is a struggle fought out between different parts of my mind on a daily basis. In your case get the .375. If nothing else they make very satisfying hole in a sheet of paper. Perhaps another generation will take it hunting.
Regards Grandpamac.
Greetings stocky and Others,Quote:
Originally Posted by Stocky
I dug out the article on the .30-06 v .30-06AI in Handloader No 123 September October 1987 written by Gil Sengel. The rifle had a 24 inch barrel fitted to a Winchester Hi Wall action. The muzzle was drilled, threaded and reamed to take three each locating pins and bolts. The barrel was 1.25 inches in dia so there was plenty of room. The barrel was then shortened to 22 inches with a parting tool and a spacer made up the same thickness as the tool and reamed in the centre to bore dia. Thus there was only a very short section un rifled. Loads were worked up in Remington cases using measurements of the solid head of the case to keep pressures equal. 150,165,180 and 220 grain projectiles were used with 5 powders. Mostly the velocity increase for the AI was between 3 and 85 fps, hardly worth rechambering for. This was with the 22 inch barrel. The 24 inch barrel produced a maximum of 60 fps extra velocity over the shorter barrel but only with the slower powders and heavy projectiles. Mostly it was less than half of that
Regards Grandpamac.
And lets not forget that a 'shortfat' case also allows each powder charge to burn more uniformly, thus giving more uniform velocities. The best way to make powder burn uniformly is to pack it into a short column. The example has been bench-rest shooters who lessened the body taper of an M43 Russian military case, gave it a sharp 30-degree shoulder, and necked it down to 6mm. These short, fat cases burned their powder charges with great uniformity = accuracy.Quote:
Originally Posted by Mauser308
But there still persists this MYTH around the 'shortfat' cartridges that:
- the shorter fatter powder column creates higher velocities with less powder and less felt recoil than a long and slender case of the same case capacity.
This idea that a 'shortfat' cartridge has some sort of 'unique length and diametric relationship' which enable propellants to be burned more quickly, thereby producing more muzzle velocity than is possible with long slender cartridges probably originated from:
- the idea that 'shortfats' have more of the propellant in proximity to the initial flame front produced by the primer. That the minimized cartridge length reduces the distance for the flame front to travel to ignite all the propellant. And that the more complete and quicker propellant ignition provided by the cartridge produces a faster pressure rise time. Therefore 'shortfats' are better in shorter barrels.
But as we have seen from this thread that is a MYTH.
If 'shortfat' cases are able to produce more velocity per grain of powder, then in the test above with the 300 WSM vs 300 H&H, the 300 WSM should have been significantly faster with the same powder charge. As it was, the WSM achieved 2918 fps at 82% of case capacity, while the 300 H&H achieved 2914 fps at 81% of case capacity.
It is true that smaller cases are more efficient in terms of fps per grain of power, however, small cases limit velocity potential. But case shape just isn't a factor in velocity. Everything in this thread seems to confirm that in regards to case design, case capacity is the only determiner of velocity not case shape.
There is nothing magical about the 'short n fat' cartridges, they don't render any 'long n slender' cartridges obsolete UNLESS you want a short action, which enables you to own a rifle that offers magnum power (ie 300 WSM), but is shorter, somewhat lighter, and handier than a standard magnum rifle (ie 300 Win Mag).
Greetings Hermitage,Quote:
Originally Posted by Hermitage
The myth was also spread by the manufactures in the early WSM and SAUM days. The 7mm Rem SAUM was promoted as delivering the same velocity as the larger 7mm Rem Mag. My 7mm Rem SAUM Sendero came close to factory claims giving 3,070 v 3,110 fps but it did so due to higher pressure. Somehow Remington forgot to mention this. Writing this I am embarrassed by the length of time since I fired the Sendero. Need to rectify that next range day.
Regards Grandpamac.
My understanding is that there are four elements to the short fatty case design that improve accuracy. If you look at how winning benchrest cases have influenced modern cartridge design, then it’s probably fair to say that the long, tapered cartridge designs of yesteryear are done and dusted.
1. Sharp shoulder angle (more positive headspacing)
2. Very little taper (co-axial alignment to the bore)
3. Longer neck length (improved concentricity)
4. Short fat case (powder burn efficiency & uniformity)
Plus of course a lot of the short fat cases are able to shoot long for calibre, high BC bullets, with chamber dimensions allowing far longer extruding bullet length than what went before.
Attachment 162340
the are all sweet. pick a calibre and shoot. The short fat ones seem to be popular in bench rest ect. br dasher 284 saum wsm. As @Flyblown said even burn ect.
the trebly has had name as being better than the 223 for accuracy....the longer neck COULD be answer....
And not a belt on any of them.Quote:
Originally Posted by Tim Dicko
Grandpamac.
