ysrracer Posted September 10, 2019 Share Posted September 10, 2019 (edited) Eight shots, 6035 divided by 8 equals 754, for a power factor of 98. If you throw out the high and low you get 4526, divided by 6 equals 754 for a power factor of 98. Edited September 10, 2019 by ysrracer Link to comment Share on other sites More sharing options...
ysrracer Posted September 10, 2019 Author Share Posted September 10, 2019 Sorry, S&W 627 five inch. Chrono two yards from muzzle. Link to comment Share on other sites More sharing options...
revoman Posted September 10, 2019 Share Posted September 10, 2019 Need to find some factory 158 Link to comment Share on other sites More sharing options...
George16 Posted September 10, 2019 Share Posted September 10, 2019 (edited) PF = weight of bullet in Gr times the average velocity divided by 1000 130x 754 = 9802/1000 = 98.02 Edited to correct my mistake. I read 180 instead of 130 Gr. Getting old sucks especially reading without my glasses. my apologies. Edited September 10, 2019 by George16 Link to comment Share on other sites More sharing options...
pskys2 Posted September 10, 2019 Share Posted September 10, 2019 2 minutes ago, George16 said: Your power factor is 135.72 PF = weight of bullet in Gr times the average velocity divided by 1000 180 x 754 = 135,720/1000 = 135.72 I don’t know how you came up with the 98 power factor. His bullet is 130 grain not 180 his numbers were right. BUT the chrono needs to be 10 feet from the muzzle and for ICORE you only need 1 shot so 130 x 813 = 105 PF still under the 120 needed. Link to comment Share on other sites More sharing options...
George16 Posted September 10, 2019 Share Posted September 10, 2019 (edited) 3 minutes ago, pskys2 said: His bullet is 130 grain not 180 his numbers were right. BUT the chrono needs to be 10 feet from the muzzle and for ICORE you only need 1 shot so 130 x 813 = 105 PF still under the 120 needed. Damn, my mistake,. I read 180. Getting old sucks. My apologies. Edited September 10, 2019 by George16 Link to comment Share on other sites More sharing options...
Prange Posted September 16, 2019 Share Posted September 16, 2019 Nice velocity spread. Wow. Link to comment Share on other sites More sharing options...
Sarge Posted September 16, 2019 Share Posted September 16, 2019 Too close to chrono. Link to comment Share on other sites More sharing options...
Hi-Power Jack Posted September 16, 2019 Share Posted September 16, 2019 On 9/10/2019 at 6:52 PM, pskys2 said: the chrono needs to be 10 feet from the muzzle It's more than likely, if you stand back about 10-12 feet, that your PF will magically increase to 127 or so. Link to comment Share on other sites More sharing options...
ysrracer Posted September 16, 2019 Author Share Posted September 16, 2019 (edited) 2 hours ago, Sarge said: Too close to chrono. You're joking right? You know bullets aren't like rockets, they don't speed up. Edited September 16, 2019 by ysrracer Link to comment Share on other sites More sharing options...
ysrracer Posted September 16, 2019 Author Share Posted September 16, 2019 2 hours ago, Prange said: Nice velocity spread. Wow. Factory ammo. Link to comment Share on other sites More sharing options...
Sarge Posted September 16, 2019 Share Posted September 16, 2019 4 minutes ago, ysrracer said: You're joking right? You know bullets aren't like rockets, they don't speed up. Muzzle blast affects chrono results when too close. This is why the instructions most likely tell you 10-12 feet. It’s why USPSA says at least 10 feet. This way you are only measuring bullet speed and not muzzle Blast. Link to comment Share on other sites More sharing options...
Mcfoto Posted September 16, 2019 Share Posted September 16, 2019 I actually read the instructions that came with my chrono and it recommended 12 to 15 feet for accurate handgun measurement. My revolver produces a similar velocity spread. It was explained to me (by someone fairly smart on such matters) that each chamber in the cylinder will chrono differently. So when developing a load, I go up to the point that all the shots in a moon make PF. Lastly, I know Blazer Brass .38 special doesn't make PF either. I've been told almost no factory ammo does. When I went to hand loading, I had to get into the +P end of the charts to make ICORE PF and push it even a little higher to make USPSA. Link to comment Share on other sites More sharing options...
ysrracer Posted September 16, 2019 Author Share Posted September 16, 2019 (edited) When I say "two yards" from the chrono, I'm not really good at measuring distance. This is ten inches, right? Edited September 16, 2019 by ysrracer Link to comment Share on other sites More sharing options...
mchapman Posted September 16, 2019 Share Posted September 16, 2019 1 hour ago, ysrracer said: When I say "two yards" from the chrono, I'm not really good at measuring distance. This is ten inches, right? No that is 6 inches!! Link to comment Share on other sites More sharing options...
MikeBurgess Posted September 16, 2019 Share Posted September 16, 2019 The velocities listed look pretty right for factory 38spl. also the velocity spread is pretty common too, think of a revolver as 6 or 8 different guns as each chamber will shoot a bit differently, when I chrono several clips through the gun I can totally see the pattern of fast and slow chambers from clip to clip Link to comment Share on other sites More sharing options...
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