.40 or .357 Sig: Which is easier on Autos?

[IanS]

I've been thinking of getting a .357 Sig barrel for my P229 (cheaper than buying a .357 Mag revolver for plinking). Is the typical 125 grain round harsher on the P229 or similar gun than a 135, 155, 165, or 180 grain .40 load? Simply, which round is easier on the gun?

Also, is transitioning to .357 more natural for the .40 caliber P229 .40 than converting a G23 to .357 Sig? And how much for a Sig .357 barrel from Sig?

 

[Gremlin]

In response to your first question, the PSI ratings of the two calibers are nearly the same so it's hard to imagine that one would be particularly harder on a gun than another.

I don't swap barrels (yet) between .40 and .357sig in any of my guns, but I own a HK USP40c and a Sig 226 in .357sig and while they're about the same age, neither one appears to be showing significant signs of wear related to shooting either caliber. A well built gun from a reliable manufacturer shouldn't show stress with either round in reasonable shooting practices...

 

[Captain]

The info I got from an ammo manufacturer is that the 40's pressure is right around 34,000...the 357 sig is around 41,000. The 40 is a bit easier on any firearm, especially one with an alloy frame!

 

[jtduncan]

Cap's right. .357 SIG conversions will be tough on any platform not set up for magnum rounds. .40SW is okay.

 

[IanS]

So does this mean the factory Sig P229 in .357 Sig is not as durable as the .40 version? As far as I know Sig uses the same slide and recoil spring. What if you shoot hot 135/155 grain loads on a regular basis? How does they compare to the standard 125 grain .357?

 

[Captain]

Ian, yes! That means your 229 in 357 will probably not last as long as a 40. However I doubt that you will put enough ammo through it to find out. Don't worry about it.

 

[BrokenArrow]

I would think the round that operates at the higher pressure would put more stress on the gun? A 180 gr bullet at 940 fps and 33,000 psi is easier on the gun than a 125 gr bullet at 1350 and 38,000 psi? A 115 9mm +P at 1250 and 38,000 is harder than a 147 at 975 and 35,000, etc.

1911s in 45 that kick more than 1911s in 38 Super seem to hold up better in the long run.

Then again, guns that were working just fine in 9mm had to be "beefed" up to fire the 40, and the pressure of the 40 (35,000) is way below the 9mm +P/NATO spec stuff (up to 42,000). Some 9mm loads are higher than the 357SIG (40,000).

So maybe you need to increase slide weight/spring strength to shorten cycle time/impact of slide on frame to prevent frame battering, but once you do that, the pressure becomes the source of excess stress on slide/barrel part of the the system?

I have no idea; we need to call an engineer?