Throat size?

[smj617]

I'm going to start loading lead for my m57 and I've only loaded jacketed bullets in the past. I've read conflicting information on the size of bullet compared to the cylinder throat size. Some sources say the bullet diameter needs to be slightly smaller than the throat diameter and some sources are saying the bullet needs to be slightly bigger than the throat, which doesn't make sense to me because I would think that the cartridge would not fit in the cylinder correctly. Any help in pointing me in the right direction would be greatly appreciated thanks.

[smj617]

I realize I should of posted this in the reloading section but I'm not sure as to how to move it there.

[arjay]

If the bullet by itself will drop through the throat,it's too small.You want a size that will hang up and needs a little push to get through.

[BLUEDOT37]

Originally Posted by smj617

...and some sources are saying the bullet needs to be slightly bigger than the throat, which doesn't make sense to me because I would think that the cartridge would not fit in the cylinder correctly.

With standard weight for caliber bullets this usually isn't a problem as the bullet doesn't extend into the chamber's throats far enough to contact them.

But if, 1)- the throats are small, &/or, 2)- the bullet is of large diameter, and, 3)- the bullet is heavy for caliber & extends deeper into the chamber's throats than normal, then the cartridge may not fully seat in the chamber because of their contact.

Ideally you want your cast lead bullets .001-.002" larger than the throats. Jacketed ideally the same size.

.

[keithherrington]

According to Jim Stroh of Alpha Precision:

"As with other firearms, accuracy of the revolver is dependent upon several factors. First, the bullet must be the correct diameter with relation to the cylinder chamber throats, and the interior barrel dimensions (the groove diameter is most often referenced, but bore diameter is important as well). When cast bullets are used, the bullet should be .0005 to .0010" larger than the barrel groove diameter. Ideally, the cylinder throat will be .0005 to.0010" larger than the bullet. To illustrate, Douglas .44 handgun barrels typically have a groove diameter of .429". The cast bullet should be .4295 to .4300". The cylinder throats should then be .4300 to .4305". Jacket bullets are more tolerant and can be groove diameter + .0010. Cylinder throats .0010" larger than bullet diameter."

I've used this approach with all of my custom revolvers with uniformly superb results.

Keith

[smj617]

This is why I'm confused. One response is telling me it's ideal to have the bullet .001 larger than the throat and another response is saying the throat needs to be .0005 larger than the bullet. I'm starting to think this is not a critical part of the setup and I should concentrate more on the bore to bullet size and not even worry about the throat size?

[steelslaver]

If you shooting a heavy SWC that has a band above the crimp groove it has to be throat diameter. I have not heard of oversized 41 mag throats or barrels. Possible I guess. I would get a mold and a .410 sizer and see what how it shoots. Unless throats are way over it will probably shoot better than 95% of shooters can. If it doesn't shoot well then worry. Another sizer is only about $30 and I don't recall ever seeing a .411 or a .4105. I guess you could hone a .410 out some if you had to.

[smj617]

I was planning on using 215 gr swc. I've only seen 2 options for that weight bullet. .411 and .410. I'm planning on measuring my throats when I get time but in the mean time I'm trying to figure out if the bullet needs to be bigger or smaller than the throat so I know which size bullet to buy. Im kind of new to reloading and I'm not sure what you mean by getting a mold and .410 sizer? I have only loaded jacketed bullets and they were 210gr .410.

[Pig Hunter]

The good thing about the .41 Mag. is the throat size has always been standardized . I've always sized to .410, with good success. I've not tried bullets more than 215 gr. but always had good luck from light to heavy loads.

[gwpercle]

Smith and Wesson model 57's and 58's are quite good about having proper dimensions and tolerances , cylinder throats, forcing cones and barrels are usually in the correct diameters.
The model 58 in my avatar and a buddies model 57 have fired thousands of cast bullets over the years. Lyman said to size them .410 , which we did. Not long ago we sluuged our barrels .... ,4093 and .4095 , so .410 worked. I tried some sized .411 and they worked just as well. Slug your bore and add .001 to your bullet and see how they shoot. Worry about throats if there is a problem .
Gary

[mozeppa]

i'll make it simple....most bores are smaller that the throat size...so skip that. (most ....measure anyway.)

take a bullet that you have sized and try to push it thru the cylinder from the front.
if it goes thru with ease, the bullet is too small.
if it won't go thru ...it's too big.

ideally ....you WANT IT to go thru, but a tight fit that takes some effort to push thru....not a lot ..but some effort.

also check all the chambers for uniform diameters.

i buy nothing but as good as i can get, S&W, Ruger, others and i sent 11 cylinders off to be uniformed because every one of them varied one to two thousandths from chamber hole to chamber hole. had one cylinder had 4 different size chambers!

[smj617]

Thanks for all the replies.