Bigger diameter - is it always safe? (At least for 9mm)

[deadsh0t]

Hello

It's advised almost anywhere (with some exceptions) to use bigger diameters, let's say for 9mm when using hard cast / coated / plated.

It will probably guarantee more accuracy. What about the pressures? Any test done? Especially with hard alloys. I've been suggested NOT TO use 357 or the gun will break much sooner (not like 1%). In this case it's a CZ Shadow2 but it doesn't matter. Any idea better than "it should work fine"?

It's hard to find a manometric barrel, so anybody found the opposite, like parts breaking much sooner by using bigger diameters?

I'm NOT talking about FMJ

The idea is : if the slug test gives a .3555 result, then .3555 bullets (of a good quality), should be used. If they fail the accuracy test, the alloy is too bad or the quality is not enough.

I'd like to understand more, since this can't just be tested in the gun

[painter]

If your barrel slugs .3555 you need a lead bullet of at least .3565.

Even hard cast lead will do no damage, even at .358. It is still way too soft to cause any premature wear.

Double based powders will do more damage than the soft lead bullets.

[Earl Keese]

It should work fine, there ya go.

[deadsh0t]

If your barrel slugs .3555 you need a lead bullet of at least .3565.

Even hard cast lead will do no damage, even at .358. It is still way too soft to cause any premature wear.

Double based powders will do more damage than the soft lead bullets.

Do you consider soft even the ones with the hardest lead alloy?

Is there a way to prove it's right? I mean, I was just advised by a mechanic not to use .357 at all if I don't want to break the gun very soon. I don't think that's going to happen but I don't want surprises, nor I want to argue forever.

I thought the same about double based powders. In fact I suspect a shadow2 I owned (even though it was faulty) broke earlier than expected by using double based powders.

[Earl Keese]

If your barrel slugs .3555 you need a lead bullet of at least .3565.

Even hard cast lead will do no damage, even at .358. It is still way too soft to cause any premature wear.

Double based powders will do more damage than the soft lead bullets.

Do you consider soft even the ones with the hardest lead alloy?

Is there a way to prove it's right? I mean, I was just advised by a mechanic not to use .357 at all if I don't want to break the gun very soon. I don't think that's going to happen but I don't want surprises, nor I want to argue forever.

I thought the same about double based powders. In fact I suspect a shadow2 I owned (even though it was faulty) broke earlier than expected by using double based powders.

.357 was recommended several times in your other thread(s). If you don't want to argue, why do you keep asking the same questions in different threads? Many of us here have used .357 bullets in our guns for thousands of rounds w/o issue. Somehow you want us to prove to you that our experience is valid? You can either trust your friend or trust what you've been told repeatedly here. Did you ask your "mechanic" friend for proof? If he's correct, it's easy to prove that something broke.
 It's virtually impossible to prove that something won't.

[DWARREN]

You need to know the bore diameter to decide which diameter bullet to use.
I have used .355/.356/.357 diameter in lead and coated and found most of my pistols like .356/.357 diameter best.
Depends on bullets also.

[painter]

If your barrel slugs .3555 you need a lead bullet of at least .3565.

Even hard cast lead will do no damage, even at .358. It is still way too soft to cause any premature wear.

Double based powders will do more damage than the soft lead bullets.

Do you consider soft even the ones with the hardest lead alloy?

Is there a way to prove it's right? I mean, I was just advised by a mechanic not to use .357 at all if I don't want to break the gun very soon. I don't think that's going to happen but I don't want surprises, nor I want to argue forever.

I thought the same about double based powders. In fact I suspect a shadow2 I owned (even though it was faulty) broke earlier than expected by using double based powders.

Yes. All lead is so much softer than the steel of the barrel there is no way any lead alloy will damage, or break it. The proof is in metallurgy. That's science. Read about the relative hardnesses of the materials involved, and decide for yourself.

Double based powder won't 'break' a firearm. It will erode the throat of the barrel, and cause the barrel to wear faster than single based powder.

[SoCal]

Hardness of Copper on the Mohs scale.     2.5 - 3
Hardness of lead on the Mohs scale               1.5

Look it up if you don't believe me.

[painter]

Hardness of Copper on the Mohs scale.     2.5 - 3
Hardness of lead on the Mohs scale               1.5

Look it up if you don't believe me.

...and steel is a 4.0 on that same scale.

[Tok36]

Hardness of Tok's Head on the Mohs scale.     12 - 13.5 

[deadsh0t]

Hardness of Copper on the Mohs scale.     2.5 - 3
Hardness of lead on the Mohs scale               1.5

Look it up if you don't believe me.

I know it, but it's more about pressures in the gun, not the barrel breaking itself due to lead. So the question could be: Will anything in the gun break sooner due to higher pressures and vibrations?

If your barrel slugs .3555 you need a lead bullet of at least .3565.

Even hard cast lead will do no damage, even at .358. It is still way too soft to cause any premature wear.

Double based powders will do more damage than the soft lead bullets.

Do you consider soft even the ones with the hardest lead alloy?

Is there a way to prove it's right? I mean, I was just advised by a mechanic not to use .357 at all if I don't want to break the gun very soon. I don't think that's going to happen but I don't want surprises, nor I want to argue forever.

I thought the same about double based powders. In fact I suspect a shadow2 I owned (even though it was faulty) broke earlier than expected by using double based powders.

.357 was recommended several times in your other thread(s). If you don't want to argue, why do you keep asking the same questions in different threads? Many of us here have used .357 bullets in our guns for thousands of rounds w/o issue. Somehow you want us to prove to you that our experience is valid? You can either trust your friend or trust what you've been told repeatedly here. Did you ask your "mechanic" friend for proof? If he's correct, it's easy to prove that something broke.
 It's virtually impossible to prove that something won't.

I ask more specific questions since some details weren't given and I found them out later on. So the question could be : did any gun break its parts by using 357/358, maybe earlier than expected?

That's not a "friend", just a teammate which knows mechanics but he may have no specific knowledge so he assumes it will damage the gun earlier. I'd like to know more, I'm not saying he's either right or wrong.

He just said it's simple mechanics / physics, a larger diameter will mean higher pressures etc... Which is kind of obvious (or almost), the real question is how much. In his opinion, it's not maybe 3% but too much more

[deadsh0t]

If your barrel slugs .3555 you need a lead bullet of at least .3565.

Even hard cast lead will do no damage, even at .358. It is still way too soft to cause any premature wear.

Double based powders will do more damage than the soft lead bullets.

Do you consider soft even the ones with the hardest lead alloy?

Is there a way to prove it's right? I mean, I was just advised by a mechanic not to use .357 at all if I don't want to break the gun very soon. I don't think that's going to happen but I don't want surprises, nor I want to argue forever.

I thought the same about double based powders. In fact I suspect a shadow2 I owned (even though it was faulty) broke earlier than expected by using double based powders.

Yes. All lead is so much softer than the steel of the barrel there is no way any lead alloy will damage, or break it. The proof is in metallurgy. That's science. Read about the relative hardnesses of the materials involved, and decide for yourself.

Double based powder won't 'break' a firearm. It will erode the throat of the barrel, and cause the barrel to wear faster than single based powder.

I'm not talking about the barrel but the gun in general due to pressure / vibrations, etc...

Except from erosion, I thought the fact that they burn faster with higher pressures, they tear the gun sooner (in general, not every double based powder)

[painter]

Double based powders don't necessarily burn faster, or with more pressure.

Many tend to burn slower, with less pressure.

[Wobbly]

I'm not talking about the barrel but the gun in general due to pressure / vibrations, etc...

Except from erosion, I thought the fact that they burn faster with higher pressures, they tear the gun sooner (in general, not every double based powder)

You need to separate Temperature, Pressure, and Velocity in your thinking.


> The addition of nitroglycerin to any "burn rate" powder (whether "fast" or "slow") makes it burn at a much higher temperature. It's that elevated temperature, right in front of the shell casing, where the combustion is the hottest. that erodes the steel of the barrel. Of course, we're talking about over the course of 30 to 50,000 firings. This is normally a very slow process, but nitroglycerin definitely accelerates the wear.

Yes, the Pressure is also highest at that same location, but that is a function of the burning powder. There is also Pressure in the chamber of Olympic air rifles, but very low Temperature. And so after 50,000 pellets, these guns show no throat erosion. They may show wear over the entire barrel due to sliding friction from the pellet, but it is not localized at the throat.


> If a given bullet's Velocity is the same with 2 powders, one a double-base and the other a single-base, then the Pressure is the same for both powders. There is a 1:1 relationship between Pressure and Velocity. That's the whole idea behind the chronograph.

Normal Pressure within the barrel will not hurt the barrel. Obviously there are ways that are not Normal where Pressure can hurt the barrel, like double loads and debris blocking the barrel. But again, these are not Normal occurrences, and no shooter plans on having these.

[Dan_69GTX]

Hmm, Lets see here.  Plated is NOT the same as coated or hardcast/plain lead!

However regarding just lead or coated...

You state:

It's advised almost anywhere (with some exceptions) to use bigger diameters....
It will probably guarantee more accuracy.

Then you stated

I've been suggested NOT TO use 357 or the gun will break much sooner (not like 1%).

By one person?!?

I'd listen to that one person, they are right!  Why listen to all others that have proven results

And....

The idea is : if the slug test gives a .3555 result, then .3555 bullets (of a good quality), should be used. If they fail the accuracy test, the alloy is too bad or the quality is not enough.

As Earl stated - You already asked that question and received answers.  Why post it again in a different thread - expecting different answers?

Regarding pressures - use a load chart, follow instructions, measure speed - is your speed too fast - too much pressure!