Does size really matter?

Thus far I've been shooting a bunch of Lucky Gunner's .357SIG ammo through my Glock 32, which has a 4" barrel. Since .357SIG's stock in trade is blazing speed, would a little more barrel help?

To find out, I took the Glock 35 I had converted to 9mm, and converted it back to its .40 configuration, and then dropped in a 5.32" Lone Wolf .357SIG conversion barrel.

I was dreading doing the re-converting, because I had even changed the extractor and trigger housing (which contains the ejector) to the appropriate 9mm parts, but I needn't have worried. Even my ten-thumbed self had the frame and slide stripped down, the parts swapped, and the gun reassembled in fifteen minutes.

So it was off to the range with a chronograph and some ammo...

American Eagle 125gr FMJ
LO: 1386
HI: 1410
AV: 1397
ES: 23.58
SD: 9.16

Federal HST Tactical 125gr JHP
LO: 1358
HI: 1416
AV: 1392
ES: 58.36
SD: 15.96

Hornady XTP 147gr JHP
LO: 1228
HI: 1259
AV: 1243
ES: 31.32
SD: 9.64

Those averages are, respectively, 53fps, 36fps, and 55fps more than the shorter-barreled gun. It's not a ton of improvement, but it's there. The long-slide gun also shot a whole bunch flatter than the compact 32. The small gun borders on being a handful, while the bigger one is almost docile. Without having yet tried them on the clock, I'm betting splits on harder targets, such as steel plates at 20+ yards, will be noticeably quicker.
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