Magsafe .38 +P in a 642?

[Vanzpp]

Hi, everyone.

I know people have a lot of different opinions regarding pre-fragmented ammo like Magsafe. Some people swear by it, others dismiss it as total junk.

In either case, does anyone know if it's OK to use the Magsafe MAX +P load in an alloy framed gun like the SW 642 if the gun is +P rated?

Thanks.

 

[HB]

I think you answered your own question, but check the manual

HB

 

[Vanzpp]

The reason I ask is because the Magsafe .38 non-P rounds are specifically listed on their web site for alloy framed guns. I'm assuming those are the older non-P alloy frames that are being refered to?

Also, the +P Max rounds are rated at over 400 ft lbs at the muzzle. Pretty intense for a .38 sp. load, but I know that velocity will drop quickly due to the fact that the bullet is so light. I'm just wondering if it's safe for an aluminum framed gun.

 

[Gary A]

I don't know what the current specifications for the MagSafe rounds are, but back when the loads were designed by and the company owned by the late Joe Zambone, he told me in a phone conversation that the Max rounds were very high pressure, I believe beyond plus P as I remember. He claimed in the conversation that they left the firearm so quickly that the high pressure was not really a problem (???!!), which I didn't really agree with, but at any rate they offered standard pressure versions to address the pressure issues in alloy-framed revolvers. Personally, I have abandoned my interest in the pre-frags so I haven't pursued the question any further. In those days I had several conversations with Mr. Zambone and found him to be very accessible and a fun conversationalist. He sold his company and had started on an adventurous retirement when he was taken much too soon.

I'd drop down a notch but I tend to be conservative. YMMV.

 

[Vanzpp]

He claimed in the conversation that they left the firearm so quickly that the high pressure was not really a problem (???!!),

Hmm.....I'm not sure about that either.

I guess it makes some sense. Velocity is built by pressure increasing in the barrel behind the bullet. It will require more pressure to push a 158 gr. bullet through the forcing cone and out the muzzle end of the barrel as opposed to a 65 gr. bullet. More pressure build up in the barrel = more wear on the gun.

 

[ugaarguy]

he told me in a phone conversation that the Max rounds were very high pressure, I believe beyond plus P as I remember. He claimed in the conversation that they left the firearm so quickly that the high pressure was not really a problem

If the max round is generating pressures greater than SAAMI +P, then it should be labeled as +P+.

Also, the +P Max rounds are rated at over 400 ft lbs at the muzzle. Pretty intense for a .38 sp. load, but I know that velocity will drop quickly due to the fact that the bullet is so light.

Muzzle energy does not equate to chamber pressure.

Velocity is built by pressure increasing in the barrel behind the bullet. It will require more pressure to push a 158 gr. bullet through the forcing cone and out the muzzle end of the barrel as opposed to a 65 gr. bullet. More pressure build up in the barrel = more wear on the gun.

Pressure is measured in the chamber. The old copper crush pressure test only measured peak pressure, and gave no indication of how long the load remained at peak pressure. Newer electronic pressure sensors measure the entire pressure curve. By using a powder that holds a moderate peak pressure longer than a powder that quickly peaks and falls at a higher pressure the lower pressure load can achieve equivalent bullet velocity to the higher pressure load. Take a look at Buffalo Bore's high velocity standard pressure .38 Special loads for an example of this.

 

[Vanzpp]

Muzzle energy and chamber pressure are not exactly the same. However, what produces the muzzle energy? It's the pressure, isn't it?

"Muzzle energy is the kinetic energy of a bullet as it is expelled from the muzzle of a firearm. It is often used as a rough indication of the destructive potential of a given firearm or load. The heavier the bullet and the faster it moves, the higher its muzzle energy and the more damage it will do."

http://en.wikipedia.org/wiki/Muzzle_energy

If there's no pressure or force behind the bullet, the bullet won't move.

http://en.wikipedia.org/wiki/Muzzle_velocity

"A gun's muzzle velocity is the speed at which the projectile leaves the muzzle of the gun....Longer barrels give the powder more time to work on propelling the bullet. For this reason longer barrels generally provide higher velocities, everything else being equal. As the bullet moves down the bore, however, the propellant's gas pressure behind it diminishes. Given a long enough barrel, there will eventually be a point in which the force of the air pressure in front of the bullet will equal the force of the gas pressure behind it. "

Believe me, I'm no physicist. I'm not trying to argue, just understand. Even if you use the exact same powder with the same pressure curve to propel a Magsafe bullet and a much heavier BB LSWCHP, won't the pressure in the chamber have to build up more to propel the heavier bullet--thus causing more wear to the gun over time?

 

[HB]

Well, it would be

1/2 X Mass of Bullet X Velocity squared

But the point is, pressures can be toyed with by changing the type of powder. Some newer loads develop much less pressure but propel the bullet at a higher velocity. I think Buffalo Bore is one of the prime examples in this instance.