.38/.357mag bullet diameter

[gonoles_1980]

Normally I order the .38 158 grain SWC cutter from xtreme or Missouri bullets. Both are out of stock. So I'm looking at what Missouri calls a .357 158 grain SWC. The only difference is that it's .358 diameter vs .357 diameter. How much difference does that really make?

I will be shooting these out of my LCR .357 snubnose with 4.5 grains of HP38.

 

[fxvr5]

Jacketed bullets for the 38/357 are generally .357". Plated, cast and lead are generally .358".

 

[Mr_Flintstone]

Normally I order the .38 158 grain SWC cutter from xtreme or Missouri bullets. Both are out of stock. So I'm looking at what Missouri calls a .357 158 grain SWC. The only difference is that it's .358 diameter vs .357 diameter. How much difference does that really make?

I will be shooting these out of my LCR .357 snubnose with 4.5 grains of HP38.

Are you referring to the MBC .357 Action SWC vs .38 Match SWC? If so, they are both .358 diameter; but the Match is Brinell 12 and the Action is Brinell 18.

 

[gonoles_1980]

The Missouri Bullets
.357 Action!
.358 Diameter
.357 Magnum
158 Grain SWC
Brinell 18
For Magnum Velocities

The xtreme Hard Cast
38-158gr. SWC
Quantity of 500
Diameter: 357

I guess since I have bought the .38 Match SWC before, the .358 vs .357 makes no difference.

So what really is the difference between the two bullets above, normally I get the xtreme hardcast. What does the .001 extra in diameter really do?

 

[Walkalong]

Sometimes it makes the difference between leading or not. The rule of thumb for lead is .001 over groove diameter, so .358 for . 357 Mag. If you are getting away with .357, then good, but .358 might shoot better, try em and see.

Lead should fit the throats, and the throats should be about .001 over groove diameter. So again, .358. Sometimes the throats are large enough to go/need to go, over .358.

 

[mdi]

.358" vs. .357" lead bullets means just .0005" difference in engagement. A larger bullet will have a much less chance of leading the barrel. You will probably not notice any difference. Shoot 'em! I have used .359"+ in some of my revolvers with no trouble but the cylinder throats will change the diameter to whatever diameter the throat is anyway...

This is why I have slugged all my firearms' barrels and measured throat diameter of my revolvers. It's easy to do, provided important info about the guns, and I know for sure my guns' critical dimensions...

 

[Mr_Flintstone]

OK, I see what you were talking about now. Here's my take on it. The xtreme hard cast is (I believe) Brinell 20. This hardness makes the lead alloy less likely to "skid" as it travels through the rifling and produce less leading so it can get by with a .357 diameter much like plated or jacketed. The softer Missouri bullets (18 or 12) are are more likely to give against the rifling and skid as they travel down the barrel. As such, they need to be of a larger diameter to fit tighter and create a better seal. At least that's the way I read it; but I'm no expert.

 

[gonoles_1980]

Thanks, I appreciate it . I think I mixed in some Missouri bullets with my extreme a while back, never noticed any difference in shooting. Though I'm far from an expert shot.

 

[Steveo_1704]

check out snscasting,.com also, imho the coating is more consistent than cheycast's or missouri's.

 

[Walkalong]

OK, I see what you were talking about now. Here's my take on it. The xtreme hard cast is (I believe) Brinell 20. This hardness makes the lead alloy less likely to "skid" as it travels through the rifling and produce less leading so it can get by with a .357 diameter much like plated or jacketed. The softer Missouri bullets (18 or 12) are are more likely to give against the rifling and skid as they travel down the barrel. As such, they need to be of a larger diameter to fit tighter and create a better seal. At least that's the way I read it; but I'm no expert.

Yes, harder will take a lot more before they "skid", braking the seal and causing gas cutting/leading, but are harder to get to bump up to seal things off if the fit is less than ideal. BHN 12 is plenty hard for most shooting. Too hard causes more leading than too soft IMHO.

 

[ArchAngelCD]

I agree, too hard can and does cause more leading than too soft in my experience.

I have never notices any inconsistencies in the coating on Missouri Bullets. They produce a good product IMO as does several other companies often mentioned on this forum.

 

[Dudedog]

The main difference between bullets MBC lists for .38 and .357 is the hardness. Lots of the same molds same dia
Most of the.38 bullets are BHN 12 most of the .357 bullets are BHN 18.
Unless you are loading heavy of full power .357 mag you will probably have better results with the softer bullets.
I would say with 4.5gr of HP38 you would be much better off with the softer BHN 12 ones but some guns tend to defy logic.

Side note: The MBC 140gr .38/.357 bullets can be fun, nice compromise between 125 and 158gr bullets
the BHN 12 (softer ones) are Cowboy #14, the harder BHN 18 ones listed for .357 are Zingers. You might want to give the Cowboy #14s a try.

 

[gonoles_1980]

Thanks guys, I will remember to get the softer bullets next time. Thought it might be a while since I just ordered 1000 of the .357. Maybe when I run out of plated .357, I could use those in my SA Bisley 5.5" to use them up, since I shoot hotter loads (not full magnum) out of it.

 

[Dudedog]

I would go ahead and give the BHN18 ones a try with your HP38 load, you will probably be fine, they may shoot great.
(just harder than they need IMO to be for that vel but the world won't end if you try them)
Different caliber but I had the .45 200gr SWCs in both BHN 12 and 18. The softer 12s were a little better for light and medium laods but the 18s were fine.
Full power .45 it was to close to call between the two.
If I hadn't been shooting the medium loads side by side I would have been happy with the accuracy I got from the BHN 18 bullets.

 

[Hondo 60]

You need to find your gun's sweet spot.

If .357" is too small you'll see inaccuracy & leading.
Only your gun can answer your question.

Happy reloading.