Win 296 question

[revbc]

I see in winchester's manual for the 357 mag (pistol loads) they require a heavy crimp when seating the bullet using W296.  They said it could give a squib load without the crimp.  Is this necessary in a rifle where you don't have the pressure and gas leak?

What do you think?

[Grumulkin]

I HIGHLY doubt that not crimping would cause a squib load.

[cwlongshot]

I HIGHLY doubt that not crimping would cause a squib load.

 Me to, BUT you could.
 One thing is for certain, you will definitely get better more consistant loads with a firm crimp and mag primer. Its the SAME for Lil gun, #9, H110 and 2400 to a lesser degree. Don't try to recreate the wheel here, just know its a required step.

CW

[Gatofeo]

I would believe the manufacturer.
After all, they're the one with sophisticated ballistic equipment to measure pressures.
They fire hundreds of thousands of rounds per year, many of them created to determine worst case scenarios.
They have trained ballisticians, chemists, physicists, engineers and other specialists to study the (sometimes subtle) effects of assembling their components into a cartridge.
I first loaded WW296 in the .357 Magnum about 1976, using the Speer 146 gr. half jacket bullet in a Ruger Security 6. I don't recall the powder charge, but it was one fierce load! If you missed the target, you gave it a heart attack from the blast or incinerated it with the muzzle flash! 
Since day one, even going back to the days of 296's predecessor 295HP, Winchester warned that a strong crimp was necessary for proper ignition and to avoid squibs.
I've found a heavy crimp necessary with 2400 in my .44 Magnum, for proper ignition, so Winchester's warning is not without precedent.
As far as proper ignition goes, the cartridge doesn't know whether it's been fired in a rifle or revolver. Proper ignition and burning of the powder can be greatly influenced by crimp.
Believe what Winchester tells you -- they have the experience and means to determine the whys and wherefores.

[Lone Star]

Actually, the cartridge is fully aware whether it is fired in a rifle or a revolver.  The revolver has a considerable freebore through the cylinder throat before the bullet hits the barrel forcing cone, allowing pressure to drop quickly as the powder is trying to ignite.  (Then the pressure can increase to above that encountered in a rifle chamber.)  Plenty of Handi and Ruger No.1 shooters fire un-crimped loads without problems since the bullet hits the leade immediately and allows pressure to build fast.  My custom .45LC Contender barrel has a short leade and works great with heavy loads of H110 and AA1680 under 250-grain bullets....uncrimped.  The identical loads just do not work in the .45/.410 barrel with its almost 2" jump to the leade.

IME the case's grip on the bullet is more important in a rifle than any crimp, and it is critical in a revolver.  Back in 1974 when I first started using W296 in my .45LC BH I had a number of squib loads even with the heaviest crimp my RCBS dies would allow.  It wasn't until after I substituted the .450" expander from a .45ACP die set that I finally got uniform ignition.

The crimp is probably necessary in any rifle with a tubular magazine for safety, regardless of any ballistic concerns.

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