When looking at reloading data, we have the starting load, the never exceed load, and (most tables) list a velocity.

What I'm not sure about is what load the velocity is intended to represent - Starting or Never Exceed? Or is it meant to be an average across the range?



Thanks to anyone who can clear this up for me!

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Too many S&W's to mention...

Both are shown in every loading manual I have looked at

It's usually pretty clear from the table, but . . .

When a table lists only one velocity, it is the velocity they measured when they tested the max load listed.

Some tables list min and max charges, and two velocities . . . the additional one is the velocity at the minimum charge.

Not sure what data you are looking at, but it's generally pretty clear. The only issue is barrel length. You need to roughly subtract 25-50fs per inch depending on cartridge & powder.

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NRA Cert. Inst. IDPA CSO

In addition to the above with some data the velocities listed bear little resemblance to the actual velocities that you may see from your loads. For example a recipe that I like for 38 special using Vihtavouri 3N37 would produce 1050 fps from a 10 inch barrel, however when tested out of my 6 inch Dan Wesson revolver with the B/C gap set at .003 inch only produces 800 fps. The lesson here is to NOT try and match the velocities you see listed in some load manuals, because it just isn't going to happen.

I think you are probably referring to data like that found on the Alliant website. They list only one load and one velocity. That is the MAX load and the velocity shown is for it.

If you read the lead-in WARNING to the data tables, you will see this:
USE THIS DATA WITH ALLIANT BRAND POWDERS ONLY.

REDUCE RIFLE AND HANDGUN CHARGE WEIGHTS BY 10% TO ESTABLISH A STARTING LOAD.

DO NOT EXCEED THE LOADS DISPLAYED ON THE SITE OR ALLIANT'S RELOADERS GUIDE.

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USAF, 69-92
Vietnam, 72-73

Keep in mind the velocity in the book is only a guide, and is what the company reached in their "test barrel". The differences and be considerable in your gun, depending on the size of your chambers, size of the bore of your gun, the B/C gap, how much crimp you put on the case, how deep you seat the bullet, etc. To really know your hand-loads, you need to invest in a Chronograph. Remember, all of this may not result in your desired accuracy. That's why you start maybe 10% below max and work up a few tenths at a time.

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H Richard
SWCA1967 SWHF244

It is not at all unusual to chrono the exact same load in two different revolvers and get considerably different MVs, even with the same barrel lengths. My theory is that it may be a result of slight bore dimensional differences and also the width of the cylinder-forcing cone gap. I have a Colt .357 Magnum w/6" barrel (1959) which consistently gives the highest MV of every load I have tested in it. The cylinder-forcing cone gap is so narrow that only the slightest sliver of daylight can be seen, probably no more than a few thousandths.