Winchester .38 Spl +P headstamps


OK guys, since you nailed my first two questions on .38 Spl. headstamps, I have one last question for you.

Both of these are nickel plated cases with no seating or crimping cannelures.

“W-W SUPER 38 SPL + P”

“W-SUPER-W 38 SPL + P”

Why the difference in the order of the “W-W” and the “SUPER”?

Is one older than the other? It seems that the “W-W SUPER” layout is pretty common as I have seen this many times and on many different calibers, but the other one is a first for me.

Bonus question: waht exactly does the “+ P” mean. I have heard many different opinions. “Plus Powder”, “Plus Power”, “Plus (high) Pressure”, etc… Any factory literature on this?

Thanks in advance,



AKMS - you are cheating. You said it was one last question, and there are two! Just teasin’. Can’t answer why Winchester chose two different formats on that headstamp.

The designation “+P” definitely means " plus pressure" or more accurately, “increased pressure” and was mandated by the Sporting Arms and Ammunition Manufacturer’s Institute (SAAMI) for rounds that are loaded to higher than SAAMI listed pressures for the specific caliber. SAAMI controls pressures, case measurements and chamber specifications, to insure the interchangeability and safety in all U.S.-made firearms, of ammunition manufactured in the USA, much as CIP does in Europe.


Sorry about sneaking the second question in! Thanks for the info on “+P”.