proper size bullets for my 1962 vintage k-frame

[zorro]

howdy , can someone give me the heads up on sizing 158 gr round nose and 200 gr round nose for my 1962 vintage model 10-5, .???

[Kraschenbirn]

Without having your bore and cylinder mouth measurements, I'd say that .358 would be a good starting point. All my .38/.357 S&Ws...which include a mid-60s M28 and a very early M586...shoot hard-cast .358s better than I can hold with little or no leading.

Bill

[MtGun44]

Slug the bore and measure the front of the cylinder holes (throats). If the
throats are a lot bigger than the groove diam of the bbl, you will have modest
success or worse with accuracy usually. An ideal throat is .001" or .002"
larger than the bbl groove diameter, and boolits sized to this throat diameter
or +.001" on the throat diameter are usually the most accurate.

That said, I'd try .358 or .359 for most .38s and see how they work. If not,
then do the measuring and see what you have.

If the throats are much smaller than the groove you tend to get fliers and
more leading, but this is relatively easily fixable by reaming the throats up
to groove diam +.002". If the throats are way too big, like groove diam plus
.006, you can't do much except live with whatever accy you get (may be OK
with jacketed) or replace the cylinder with one of proper dimensions - pretty
expensive.

Read the sticky on revolver accuracy for more info.

Bill

[zorro]

howdy is it commen to have different dimesions the the cylinder diameter and the bore diameter ???
zorro

[HeavyMetal]

An old reloaders trick: Take a cast bullet and drop it through the cylinder from the chamber end (just like you were loading a live round) If it fall through it's to small in diameter, if it doesn't fall through see if it's just a snug fit( easily pushed through the mouth of the cylinder) or if it requires some force.

What you want is for the bullet to require slight pressure to pass through the cylinder mouth. To much of the required push and you'll jack pressures to high and get spitting.

Yes it is a reality that the "throats" of many revolver cylinders are over or undersized. Smith and Wesson had a ton of 625 45 Auto revolvers with "throats" way to big for the barrel back in the late 80's and nobody was happy with them.

Having said all that I'll second the opinion that .358 is a real good place to start! K frames of that era were more likely to be right on than later ones. The big rush to provide handguns would not start till the early 70's and thats when QC started to slip at all makers.

[mooman76]

Unfortunately the diameters are not always ideal and this is not uncommon. Sometimes you even get different diameters in the different cyl. holes of the same cyl.
Heavymetal, that's a neat trick and the first I have heard of it but I will be sure to try it. That's something you could try when out gun shopping. I've slugged all my rifles but heven't slugged my pistols because most of them already shoot better than I can anyway!

[Bret4207]

Before you start slugging or trying to determine the correct diameter CLEAN the cylinders and barrel. I didn't once and later found almost .002 worth of crud in the cylinder throats.

[miestro_jerry]

I agree with Bret, clean your bore extremely well, there will be differences if you don't.

Jerry

[xtimberman]

I slugged my 1965 M-15 years ago, so I scrubbed the bore and throats and checked the dimensions again. Nothing changed, so It must've been clean before!

Bore is .356" and the cyl. throats are .357". Your M-10 is probably the same, but you need to check it to be sure.

A lot of folks who've tried to pound a hard alloy cast bullet down their barrel are reluctant to try it again! Get yourself some soft pure lead round balls for your bore slugging chores and you'll never be reluctant again. For .38s, a .375" ball slightly smushed and tapped into the end of the barrel will upset to the internal dimensions very easily and can be tapped through with a wooden dowel. A short piece of an old cedar arrow shaft is just the right diameter for .38/.357 bores.

Hard alloy bullets usually work OK for slugging cylinder throats because you don't have to tap them so far.

Get one of your friends who shoots .375" pure lead round balls in his .36 Navy to give you a few to slug with.

xtm