627-5 Cylinder Throat Sizes

[azdover]

Does anybody else have measurements for the cylinder throats on their 672-5s? And how do they shoot?

I have an older 627-5, early 2008 build date, and am have problems getting decent groups with it. It shoots 3-4" groups at 15 yards single action off a rest with both factory and Hornady XTP 158gr handloads, both full power and reduced. I'm not a good shot, but I'm not THAT bad.

Using pin gauges, five of my cylinder throats measure .3600" and the other three .3605". The cylinder throats in my other two Smith 357s - a 627-0 and a 686-6 - both measure .3575".

The barrel slugs at about .355-.356, so I don't think that's a factor.

BC gap is about .005" and the cylinders all line up with the barrel when checked with a range rod. Carry up is also good.

An internet search suggests oversize cylinder throats sometimes cause larger groups and smaller cylinder throats may tighten up groups.

Just trying to get an idea if my cylinder throats are oversized.

Pete

 

[Alk8944]

If you think your accuracy issue is because of the larger throats, and you are shooting cast bullets, then simply size your bullets to throat diameter or .001-.002" larger instead of replacing the cylinder! If you are shooting jacketed bullets the slightly larger throats usually make no difference!

It is not possible to check barrel-cylinder alignment with a range rod. Range rods are usually no larger than .348" or they wouldn't pass freely down the barrel. A range rod will only tell you if there is gross mis-alignment between the barrel and cylinder because the throats are at least .357" or .011" larger than the range rod. You wasted either your time or money using a range rod, especially if you bought one.

 

[Protocall_Design]

Maybe it just needs the forcing cone and/or the muzzle crown recut.

 

[taz666]

Practice ... practice .. practice.

 

[Yendor357]

Sell it. Or retire it. If it shoots 4 inch groups at 15 yards with XTPs, there's no quick and easy fix. Based on my recent experience with S&W customer service, that's just more frustration waiting to happen.

Most respectable gun shops have a new Python or 2 under the glass. The rear sights are fine. The stocks/grips are fine. The single action trigger needs the attention of a good gunsmith.

Go on Gunbroker, find a nice 5/686.

If your gun is a six shooter and you can't bear to part with it, have it turned into a 44 Special.

I've wasted too much time and ammo trying to get inaccurate guns to be accurate. Either they are, or they aren't.

 

[Protocall_Design]

He was shooting single action from a rest. That should be one ragged hole doing it like that.

 

[Bullet Bob]

"An internet search suggests oversize cylinder throats sometimes cause larger groups and smaller cylinder throats may tighten up groups."
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Not all that long ago the late Mike Venturino wrote an article about what "everybody knew" versus his actual experience over the years. I have to overcondense the article, but basically when talking about cylinder throats, bullet sizes and hardness, and bore diameters, you can't really know about your individual gun and load until you try it. Sometimes it'll surprise you and defy convential wisdom.

Best thing I've read in a gun magazine in a while.