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OK, here is the skinny. See my response above too.
This is with the same charge of the same powder, fired in the same weapon on the same day.... Everything is the same except the crimp or lack of. I don't know how to quantify the degree of crimp. My guesstamation.
Sorry spread sheets don't copy and past well.
Velocity - weapon - date - note
1256.2 S&W M29-2 9/25/13 10 rnd tested no crimp
1291.1 S&W M29-2 9/25/13 10 rnd tested medium crimp
1242.6 S&W M29-2 9/25/13 10 rnd tested heavy crimp
This is only valid with this one component loading. The powder use is 2400, the primers CCI SLP. I have ran the same comparative test with 231 powder and velocities remained within the normal spread, so the only effect I could see was more working of my brass.
Now to primers. I know this isn't part of the question, but...
1079.3 S&W M29-2 9/28/13 5 rnd test S
1116.5 S&W M29-2 9/28/13 5 rnd test M
1088.8 S&W M29-2 9/28/13 5 rnd test S
1127.6 S&W M29-2 9/28/13 5 rnd test M
1148.8 S&W M29-2 9/28/13 5 rnd test S
1150.6 S&W M29-2 9/28/13 5 rnd test M
These are the same charge of 2400 with a standard primer (CCI) on top and a Magnum primer (CCI) below, with one tenth of a grain of powder increase from set to set.
The listed velocities are averages of each tested shot. As these were testing samples, a statistically valid number of samples were not tested, this will only be a 'tendency to'.
It should be noted that these were 240 grain cast lead bullets and the first set with no crimp did show some bullet walk but not enough to lock up the cylinder by far. If the movement had been much I would have single loaded each for testing.
As stated before, no crimp for my wimp load (5.6 grains of 231 with 240 grain lead) and yes it is a wimp load at 643 FPS. Heavy loads may need to be crimped, I do.
Load with care,
OSOK
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