357 125 gr. velocities: 4" vs. 6" bbls

R

Rusty S

New member
I vaguely remember a rule of thumb that went something like +/- 75 fps for 4" vs. 6".

On the other hand, last I looked hard at some actual 6" velocities over a chronograph, they sure came awful close to published 4" factory vented barrel velocities. Does that mean the factory stats have, shall we say, been optimised?

I know everything but the phase of the moon impacts velocities. But I just ended up with an nib M19 4" and a nice tight M19 6".

So if you took 5 4" M19 exemplars and another 5 6" exemplars, what's the average difference going to be? Say 125 gr. 357 full-charge loads from Remington, Winchester, Federal, CCI/Speer, Eldorado, and Cor-Bon.

Give me your best guess what the difference would be.
 
There have been "group shoot" articles in the past doing exactly what you propose, and the general answer is that the 6" guns will show higher velocity. The averages may support the "rule of thumb" of gain or loss per inch and they may not. It is not unusual to find a 4" in a batch of five guns that will shoot very nearly the same velocities as the 6" guns. Those guns sort of tilt the averages. It is an interesting exercise, but usually produces nothing more than the general results. The differences between "identical" revolvers is too great to make the results meaningful. The variations in fitting, bore and cylinder measurements, etc., etc. make the revolver seem like the bumble bee. From a purely engineering standpoint, one can't fly and the other can't shoot. Fortunately, mine don't know this, and when the clover blooms in the yard, it is full of dumb bumblebees flying around. Even the rule of thumb rambles a bit. I've always used 50 fps. My 2 1/2" 686 clocks the old 125 gr. Remington, rated at 1450 fps, at an average of 1375 and it is ported. Durn bumblebee :p
 
Size matters

Frankly, I distrust 'averages'; I prefer to test then know; know what I mean?

What does YOUR gun do?
 
They are often amazingly close. I can group a bit better from the bench with the 6" but there shouldn't be much difference between four and six on the receiving end.
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4 inch versis 6 inch velocity

The Elmer Kieth method is to deduct 33 feet per second for a know velocity, per inch you shorten the barrel. 66 Feet per second difference?
 
Just what is the diff?

Wonder if your concern is whether there is any substantial performance difference with the longer barrel, on target? I think that test barrels almost always seem to give higher velocities than real guns. Probably different chambers in the gun affect velocity too. I have a Colt with one throat slightly looser than the others and it might be lower velocity on that one. Too many variables to probably calculate from just length. But the advantage of the longer barrel is sight radius and probably faster recoil recovery. Some have given me generalisations like "the .357 really comes into it's own in 6 inch or longer barrels" but I have been just as happy with my 4 inchers. Maybe if you were taking it hunting it would be an advantage.
 
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