9mm vs Short Colt. ICORE,

[radny97]

17 hours ago, varminter22 said:

I understand that!  

 

But if that is true (and I saw your SAAMI ref), why aren't ammo manufactures (and us handloaders) loading all .38 Spec/.357 Mag/etc ammo with .355"/.356" bullets?  

 

I also understand that barrels can and do vary, but they should be with the .0004" or .0005" tolerance, correct?  And barrels can vary a little in bullet preference.  But a .358" bullet in a .3546" barrel??  Interesting.  

 

Said another way:  Since you said "SAAMI defines the standards, and companies build their products around them" why wouldn't the standard bullet diameter for both calibers be .355"/.356"? 

 

16 hours ago, superdude said:

 

There is no such thing as a 38/357 barrel and a separate 9mm barrel. They both have the exact same specs. 

 

If you buy a 38/357 revolver and the barrel groove diameter measures .355", does that mean it has a 9mm barrel?  No, it doesn't. That's because .355 is within the SAAMI specs for a 38/357 barrel. It's still a 38/357 barrel. 

Not true. 357 mag barrels have 1/18 twist while 9mm barrels have 1/10 twist. 

[superdude]

The twist rate is different (though optional), but the groove diameter specs are the same.  The groove diameter being the same is what people go nuts over. 

[MWP]

4 hours ago, Toolguy said:

The main thing to remember is you always want to go from bigger to smaller. For example, if you have .358 bullets, you can go to .357 throats and .355 barrel and be OK. If you have .355 bullets and .357 throats and barrel, it may not work as well. If the barrel has a tight spot where it threads into the frame, it will swage the bullets down and they will rattle down the rest of the barrel causing leading and large groups.

I think this is exactly why I’ve had really good luck with my aftermarket barrels and 358 coated bullets of all weights. 358 bullet, most likely a 356-357 cylinder throat from a factory 929 cylinder, and a true 355 barrel. 

[MWP]

4 hours ago, Toolguy said:

The main thing to remember is you always want to go from bigger to smaller. For example, if you have .358 bullets, you can go to .357 throats and .355 barrel and be OK. If you have .355 bullets and .357 throats and barrel, it may not work as well. If the barrel has a tight spot where it threads into the frame, it will swage the bullets down and they will rattle down the rest of the barrel causing leading and large groups.

Short stroke. 

Edited November 17, 2022 by MWP

[MikeBurgess]

2 hours ago, mchapman said:

Kirby G, Vic M and Billy S all had them, built by the guy in Phoenix , so I think that there were at least 4 of them, but I could be wrong, I've seen 3 of them.

Cool, I only ever saw pictures of one on here 

 

[gargoil66]

21 hours ago, testosterone said:

 

Not a machinist, you need a vblock to do this measurement properly anyways, no?

TT:

 

I am not a machinist either.  What's a 'V' block?

 

GG

[gargoil66]

21 hours ago, testosterone said:

 

Not a machinist, you need a vblock to do this measurement properly anyways, no?

TT:

 

I am not a machinist either.  What's a 'V' block?

 

GG

[ysrracer]

41 minutes ago, gargoil66 said:

TT:

 

I am not a machinist either.  What's a 'V' block?

 

GG

A block in the shape of a V ?

[Toolguy]

You need a micrometer to measure the bullet diameter after it's been pushed through the barrel. For an even number of lands and grooves, a regular micrometer works. Six lands and grooves is common, there are many others.

 

For an odd number of lands and grooves, you need a V anvil micrometer made for that number. Five lands and grooves is common, there are others. Most of the current S&W revos have 5 lands and grooves, which makes measuring the bullet problematic unless you have a V anvil micrometer (mike) made to measure 5. These are most often used to measure cutting tools with 5 flutes, like an end mill, reamer, special drill bit, etc.

[testosterone]

2 hours ago, Toolguy said:

You need a micrometer to measure the bullet diameter after it's been pushed through the barrel. For an even number of lands and grooves, a regular micrometer works. Six lands and grooves is common, there are many others.

 

For an odd number of lands and grooves, you need a V anvil micrometer made for that number. Five lands and grooves is common, there are others. Most of the current S&W revos have 5 lands and grooves, which makes measuring the bullet problematic unless you have a V anvil micrometer (mike) made to measure 5. These are most often used to measure cutting tools with 5 flutes, like an end mill, reamer, special drill bit, etc.

as defined by an actual machinist

 

This is why, mostly, when someone says they slugged a barrel I have considerable doubt regarding the measurements accuracy.

Edited November 18, 2022 by testosterone

[gargoil66]

Warren:

 

Thanks for that info.  I have slugged a number of barrels to find most of them five groove.  Impossible to measure with a standard calipers.  Don't even want to think of how much a v block micrometer costs. 

[Toolguy]

Under $200 if you know where to look. Much more otherwise.

 

https://www.shars.com/products/measuring/micrometers/0-2-1-108-degree-5-flutes-measured-v-anvil-micrometer

[ysrracer]

33 minutes ago, Toolguy said:

Under $200 if you know where to look. Much more otherwise.

 

https://www.shars.com/products/measuring/micrometers/0-2-1-108-degree-5-flutes-measured-v-anvil-micrometer

So you're saying a v-block micrometer has a block shaped like a V ?

 

Interesting.

[Toolguy]

Click on the link and look at the picture.

[ysrracer]

1 hour ago, Toolguy said:

Click on the link and look at the picture.

 

Make me

[Toolguy]

I don't make anyone do anything. Everyone is free to do as they wish. That was a suggestion, not an order.

[BHBret]

OK, the v-block hurts my head. As the diameter of any object gets bigger the position in the V gets further from the corner of the V. Does the reading of the caliper takes that into account so you directly read the outside diameter?

[testosterone]

1 hour ago, BHBret said:

Does the reading of the caliper takes that into account so you directly read the outside diameter?

you are thinking to hard

[Toolguy]

Yes, you read it like a normal mike. That's why the angle of the anvil only works for one number of flutes. For example, a V anvil mike for 3 flutes is very different to a V anvil mike for 5 flutes, etc. Even numbers can be measured with a regular mike because there will always be 2 that are directly opposite.

[gargoil66]

3 hours ago, Toolguy said:

Yes, you read it like a normal mike. That's why the angle of the anvil only works for one number of flutes. For example, a V anvil mike for 3 flutes is very different to a V anvil mike for 5 flutes, etc. Even numbers can be measured with a regular mike because there will always be 2 that are directly opposite.

 

Warren:

 

Yes, I have seen them before but never used one.  Makes sense that they would be shaped differently for different number of flutes.  Am past the stage of slugging barrels so leave all that to you guys who know what you are doing.

 

Thanks for the info once again.  

 

GG

[ysrracer]

6 hours ago, testosterone said:

you are thinking to hard

 

Agreed, just load up some bullets and see how they shoot.

 

I did a side by side test with four different brands. No difference at 25 yards.