Unexpected chrono results w 9mm LCR vs LC9

[Greybeard]

Got some rather unexpected results in "laboratory" session last week using the same special "short barrel" Gold Dot ammo in both guns. Chronograph set up 10' from the muzzle showed 2" barrel 9mm Ruger LCR shot FASTER than 3" barrel LC9-s. So, we set up again last night and tested four more various flavors of ammo. Bottom line: In 3 of 5 cases (shooting 3 to 5 rounds from each) the 2" snub revolver shot faster than the 3" semi. Go figure.

Speer Gold Dot 124 grain "short barrel": 1,142 fps out of LCR vs 1122 out of LC9
Federal (alum case) 115 grain FMJ: 984 out of 2" revolver and 1,029 out of 3" semi
* Monarch 124 grain FMJ: 1,068 out of 2" revolver and 1,015 out of 3" semi
** Federal 124 grain HST: 1,047 out of revolver and 1,064 out of semi
Remington UMC 115 grain: 1,050 out of 2" revolver and 1,038 out of 3" semi.

* Very inconsistent 5 shot strings. High/low out of revolver: 1,289/998 High/low out of semi: 1289/938
** Most consistent 3 shot strings. High/low out of revolver: 1,071/1024 High/low out of semi: 1070/1059.

[howdy]

I didn't know the LCR came in 9mm. I looked it up and it does. See, you can always learn something from the Texas CHL Forum.

[Greybeard]

LCR has only been available in 9mm for a few months. I sold .38+P LCR to buy the 9, primarily for training ammo compatiability and cost purposes. Altho 9mm is generally more efficient out of short barrels than .38. The numbers above rival some we have seen from even 2" .357s. Lotsa blast and flash for not much more fps.

[C-dub]

With the possible exceptions of the Federal 115 gr and Monarch the others may be with reasonable normal variation for such a small difference in barrel length of two short barrel guns.

These are percentage of differences between the two handguns.
Speer Gold Dot 124 gr -1.8%
Federal 115 gr FMJ 4.4%
Monarch 124 gr FMJ -5.2%
Federal 124 gr HST 1.6%
Remington UMC 115 gr -1.2%