CMV
Member
I loaded all the rounds for it so I guess it's reloading related....
Anyway, for this year's (7th grade) science fair I helped as usual. We did "does a bullet go faster from a shorter or longer barrel?"
Not at all PC and we'll probably get a letter sent home or something to that effect for just sending pictures of firearms to school, but he probably had the most fun out of all the kids doing his project. And he did learn something - his hypothesis was that it would go faster from the shorter barrel because there is less friction traveling a shorter distance in the barrel.
We tested 9mm out of 3.25", 4.9", & 16.6" barrels and .223 out of 16" & 20" barrels. I was a little surprised to see that a 9mm went about 150 fps faster out of the 16" Beretta CX4 vs the 5" Beretta 92FS - I didn't think there would be all that much difference past 5" for a pistol round - but it was about 13% more.
Loads were 4.8gr W231 + 115 gr Hornady FMJ & 24.2gr H335 + 55gr Hornady FMJBT. Avg vel for 10 shot strings (Chrony worked wonderfully on this overcast day with 0 errors for this & a bunch of other testing):
9mm
3.25" 1090 fps
4.9" 1144 fps
16.6" 1290 fps
.223
16" 2777 fps
20" 3031 fps
Anyway, for this year's (7th grade) science fair I helped as usual. We did "does a bullet go faster from a shorter or longer barrel?"
Not at all PC and we'll probably get a letter sent home or something to that effect for just sending pictures of firearms to school, but he probably had the most fun out of all the kids doing his project. And he did learn something - his hypothesis was that it would go faster from the shorter barrel because there is less friction traveling a shorter distance in the barrel.
We tested 9mm out of 3.25", 4.9", & 16.6" barrels and .223 out of 16" & 20" barrels. I was a little surprised to see that a 9mm went about 150 fps faster out of the 16" Beretta CX4 vs the 5" Beretta 92FS - I didn't think there would be all that much difference past 5" for a pistol round - but it was about 13% more.
Loads were 4.8gr W231 + 115 gr Hornady FMJ & 24.2gr H335 + 55gr Hornady FMJBT. Avg vel for 10 shot strings (Chrony worked wonderfully on this overcast day with 0 errors for this & a bunch of other testing):
9mm
3.25" 1090 fps
4.9" 1144 fps
16.6" 1290 fps
.223
16" 2777 fps
20" 3031 fps