jframe cyl specs

[dave in maine]

the front of the cyl mikes .354,that seems a bit tight to me it is a used mod 36 and i'm thinking it will build up pressure.all cyls mike the same,and no signs of leading.any thoughts?

 

[dave in maine]

the front of the cyl mikes .354,that seems a bit tight to me it is a used mod 36 and i'm thinking it will build up pressure.all cyls mike the same,and no signs of leading.any thoughts?

 

[john traveler]

I remember reading what Roy Jinks wrote at one time. S&W encountered complaints from users of lightweight/hard recoiling revolvers causing the bullets to "jump" the crimp and jamming up cylinders, preventing functioning. The S&W engineering solution was to reduce chamber throats a couple thousandths to prevent this. I would not swear to it, because I have not measured a large sample of Airweight and compact revolvers, but that is probably what you have. What isserial number and year of production?

 

[dave in maine]

the serial # is j164xxx and i believe the year of manufacture is 1973-74 thanks for your help,i need to know the gun is safe to use.
dave

 

[Alk8944]

dim,

Did you use an internal micrometer or plug guages to measure the throats, or a dial caliper? Any measurement of the internal diameter of a round hole attempted with a dial caliper will be found to be .002-.005" smaller than the actual hole, depending on diameter, as the edge of the blades have a small flat that does not measure to the actual widest point in the hole. Precisely measuring the diameter of a hole is difficult tp do accurately.

The easiest way to accurately measure a throat is to push a slightly oversize soft lead slug through the throat and measure that with an outside micrometer.

 

[dave in maine]

alk i had no idea that was the case,i'll give that a try all i have is a dial caliper will that do as well as a micrometer?
thanks for your help.
dave

 

[john traveler]

A typical 0-1" micrometer is four times as accurate as a typical 0'6" dial caliber, but the caliper will do for your purposes. Alk8944's advice to measure a soft lead slug pushed through the chamber throat is a good one.

What you want to know is whether the chamber throats are typically within the 0.0356"-0.0358" range of nominal .38 Special throats.

 

[Hoptob]

The easiest way to accurately measure a throat is to push a slightly oversize soft lead slug through the throat and measure that with an outside micrometer.

+1.

Just remember to remove cylinder from the frame before slugging or you will likely damage the crane.

There is also a quick and dirty way to check the throats. You can select several 9mm and 38spl bullets measuring 0.354-.358 with 0.001 increments and use them as poor man's plug gauges.

Mike

 

[dave in maine]

the one that i slugged is .356 so what would explain the case impressions on the back? the bluing is gone where the cases sit.

 

[john traveler]

If you are talking about blue loss where the caseheads rub against the frame (the recoil shield) or the cylinder where the case rims touch, that would indicate that the revolver has been fired a LOT or carried a LOT.

Nothing to worry about if the gun is serviceable otherwise. Your chamber throat measurement at 0.356" is within specifications too.

 

[dave in maine]

john it seems as though it might have been carried alot,the recoil shield is what i was trying to describe,chalk it up to crs.i'm thinking mostly holster wear.the r h grip is bare and the left still has finish on it.the cylinder is barely ringed after deer season i'll take it out back and try it out.
thanks for everybody's input
dave

 

[Tom C]

Concur that measuring throats with dial caliper is not accurate enough. I got a set of plug gages and I measured every revolver I own.
27-2 .358"
627-5PC .357"
60-15 Pro .357"
60-18 .358"
360 Kit Gun .359"

 

[dave in maine]

tom what are plug gages,and where did you get them?