speed ?

[lincoln45]

so i crono'd my three 1911's all in .45ACP

i have two 5" guns a Loaded and a MC Operator

i was very surprised there was a diffrence between these two I assumed since they were both 5" they would be the same....

naturally the 3.5" Ultra Compac was significantly slower...

thoughts....

[XDRoX]

Chamber and Bore size.

[J-cat]

has nothing to do with anything.

You can take two identical barrels with identical dimensions and one will be slower, or not. One will be more accurate, or not. There's no way to predict it.

[joelogic]

What's up with no numbers?

[lincoln45]

Unique.....5 round average
5.4 grns
MC....738
Loaded...697

5.6 grns
MC... 749
Loaded....726

5.8 grns
MC....800
Loaded...794

[Bill Steele]

Looks like the MC barrel is slightly faster. How many jacketed rounds total through each?

[lincoln45]

MC less than 500
Loaded several thousand

[Bill Steele]

Looks like things will stay that way.

[stilly]

so i crono'd my three 1911's all in .45ACP

i have two 5" guns a Loaded and a MC Operator

i was very surprised there was a diffrence between these two I assumed since they were both 5" they would be the same....

naturally the 3.5" Ultra Compac was significantly slower...

thoughts....

Did you shoot the exact same bullet/powder charge from both guns? The answer is no.

You shot different rounds, that means different brass and different bullets and different powder charges. Even same headstamp brass can vary in weight.

You mention 5.4, 5.6, and 5.8gr of powder but that could also be taken as

5.41, 5.42, 5.43, 5.44, 5.45, 5.46, 5.47, 5.48, 5.49...

I find that there CAN be quite a bit of difference in small amounts like that when dealing with smaller quantities. (pistol rounds)

I think the best that could have happened was to see if the rounds FIT in all guns, but only shooting a sample from one gun vs another.

Could have been that the Loaded or the Operator got the higher powder charges.

All of those variables should be taken into account when doing a test like this. Try to get a more accurate powder reading first, then maybe weigh brass and bullets for consistency and check length cause I have brass all over the place and that will AFFECT crimp too which might also have an effect on the starting pressure (see what I did there?)

That is what I would have done anyways but doing these chrono tests suck. I am tired of shooting over my chrono and find myself seeing how close I can shoot over or if just a little more and I actually hit it... It already has a partially melted face from my Dealge.

What chrony did you use also?

[SixPointEight]

Different guns just shoot different. 40fps? That's about right. Some loads shot the same. Also, that's a 5 round average, it's not statistically valid. Shoot a hundred of the same through each. Calculate the mean and the standard deviation. Then you can talk about what shoots differently, and it will be a meaningful conversation. With the data you have, it's random chance, and you're over analyzing 5% of a statistically insignificant sample size.

[M27]

Did you shoot the exact same bullet/powder charge from both guns? The answer is no.

You shot different rounds, that means different brass and different bullets and different powder charges. Even same headstamp brass can vary in weight.

You mention 5.4, 5.6, and 5.8gr of powder but that could also be taken as

5.41, 5.42, 5.43, 5.44, 5.45, 5.46, 5.47, 5.48, 5.49...

I find that there CAN be quite a bit of difference in small amounts like that when dealing with smaller quantities. (pistol rounds)

I think the best that could have happened was to see if the rounds FIT in all guns, but only shooting a sample from one gun vs another.

Could have been that the Loaded or the Operator got the higher powder charges.

All of those variables should be taken into account when doing a test like this. Try to get a more accurate powder reading first, then maybe weigh brass and bullets for consistency and check length cause I have brass all over the place and that will AFFECT crimp too which might also have an effect on the starting pressure (see what I did there?)

That is what I would have done anyways but doing these chrono tests suck. I am tired of shooting over my chrono and find myself seeing how close I can shoot over or if just a little more and I actually hit it... It already has a partially melted face from my Dealge.

What chrony did you use also?

While yes there is a difference between 5.41 and 5.42 and all that other stuff you said he did 5 shot averages. This should help to get rid of the outliers. The chances that out of the 30 rounds he shot all 15 higher powered rounds randomly went to one pistol and the lower powered to the other is a statistical 0.

I would be really interested in seeing this test done again with 50 rounds or more through each pistol. Maybe it's in my inner math nerd but more data is always better.

[jameshenry]

I don't have a chrono and after reading all the above am not going to get one. My head hurts.

[HighLander51]

Most of this doesn't really matter unless you are a top Bullseye shooter. But to get valid data, you need to weight the bullets and same head stamp cases and powder charge to within +/- .01 grains, measure to same AOL, run a few fouling shots, then start measuring, clean barrel after every couple of rounds, try to keep the barrel temp about the same. Your variance should drop to like +/-10 fps for each barrel.

[Bill Steele]

I don't have a chrono and after reading all the above am not going to get one. My head hurts.

You were probably joking, but if not, chrony's are a great tool when doing load development. I don't use them as much for handgun loading, except when I was fooling around with really hot 10mm loads. During that period, the instrumentation the chrony provided was vital.

[lincoln45]

the purpose of this experiment was to find the bottom load that will work in three diffrent guns and still stay above min required by IDPA....so as far as i'm concerned it was a success

the powder was as acurate as the digital scale

did not factor case specs or bullett specs....both random from the bucket

for rifle hunting rounds i do get anal but not for holes in paper