Chris_Andersen Posted June 18, 2009 Share Posted June 18, 2009 So I know that barrel length can make a difference in what the chrono shows when firing the same bullet in different guns...But I am experiencing pretty large variations with what I am currently loading and wanted to know you guy's thoughts. I have a 9mm 115gr round with 4.3gr Universal Clays powder 1.13 OAL Fired through my M&P Pro with storm lake barrel, the run at 1100 FPS all day long give or take 10-20 FPS When I run them through my stock Glock 19 they are all over the place. some are 1100 FPS but I get others as high as 1400, even 1700 fps. What am I seeing here? Link to comment Share on other sites More sharing options...
D. Manley Posted June 18, 2009 Share Posted June 18, 2009 So I know that barrel length can make a difference in what the chrono shows when firing the same bullet in different guns...But I am experiencing pretty large variations with what I am currently loading and wanted to know you guy's thoughts.I have a 9mm 115gr round with 4.3gr Universal Clays powder 1.13 OAL Fired through my M&P Pro with storm lake barrel, the run at 1100 FPS all day long give or take 10-20 FPS When I run them through my stock Glock 19 they are all over the place. some are 1100 FPS but I get others as high as 1400, even 1700 fps. What am I seeing here? I'd say you're seeing a problem with the chrono. Link to comment Share on other sites More sharing options...
Viggen Posted June 18, 2009 Share Posted June 18, 2009 There is likely to be variation from pistol to pistol and barrel to barrel. But extreme variation like you mention is likely something else. 1400 nd 1700 fps are a bit outside the normal territory. As suggested, look to your chrono. Things like shade or where you aim may also be affecting things on your particular chrono. Link to comment Share on other sites More sharing options...
G-ManBart Posted June 18, 2009 Share Posted June 18, 2009 Glock barrels tend to run on the fast side, but not that fast! My M&P Pro with Atlanta Arms 147gr JHP (new cases) runs within about 20fps (slower) of what they said they normally see out of a Glock 34. Unless you chrono'd back to back with the two guns it's almost certainly a chrono/lighting issue. Try using a cardboard target upside down (white side facing sensors) over the sky screens and, if necessary, pieces of cardboard on the sides to keep direct light from hitting the sensors as well. A chrono box with it's own lighting (IR is popular in this setup) is the best, but sort of a pain to lug around. R, Link to comment Share on other sites More sharing options...
Chris_Andersen Posted June 18, 2009 Author Share Posted June 18, 2009 (edited) Glock barrels tend to run on the fast side, but not that fast! My M&P Pro with Atlanta Arms 147gr JHP (new cases) runs within about 20fps (slower) of what they said they normally see out of a Glock 34.Unless you chrono'd back to back with the two guns it's almost certainly a chrono/lighting issue. Try using a cardboard target upside down (white side facing sensors) over the sky screens and, if necessary, pieces of cardboard on the sides to keep direct light from hitting the sensors as well. A chrono box with it's own lighting (IR is popular in this setup) is the best, but sort of a pain to lug around. R, These numbers were back to back. That is why I was unsure what was going on. I have also seen similar variations with different load combos with these 2 guns. Where can get an infrared setup? I have a Chrony Beta Master. Edited June 18, 2009 by BCA Link to comment Share on other sites More sharing options...
Chris_Andersen Posted June 18, 2009 Author Share Posted June 18, 2009 (edited) Just read a few posts on the forum about chrono lighting. This was at the end of the day with the setting sun behind me. But the guns were back to back, with several different loads, chrono at 8 ft away, punching holes in a 1 inch group in a 10 yard target, so I think they were all going into the same spot in the chrono Edited June 18, 2009 by BCA Link to comment Share on other sites More sharing options...
njl Posted June 23, 2009 Share Posted June 23, 2009 1700 fps has got to be a false reading. I mean that'd be just crazy hot for 9mm. If it was legit, you'd have noticed it (louder bang, nasty recoil). Using the same powder and charge, I consistently get around 1050 fps with 124gr jacketed bullets from a G17. Link to comment Share on other sites More sharing options...
G-ManBart Posted June 23, 2009 Share Posted June 23, 2009 Just read a few posts on the forum about chrono lighting. This was at the end of the day with the setting sun behind me. But the guns were back to back, with several different loads, chrono at 8 ft away, punching holes in a 1 inch group in a 10 yard target, so I think they were all going into the same spot in the chrono I don't think anybody makes an IR setup for the Shooting Chrony line unfortunately....haven't checked their website, but I don't recall it as an option. At 8ft I'm wondering if the shorter barrel on the Glock is spitting some unburned powder (shorter barrel) or the concussion of the round going off it tricking the chrono. I'd try moving it back a couple of feet to see what happens. I tend to set my chrono at 12-15ft. R, Link to comment Share on other sites More sharing options...
HSMITH Posted June 23, 2009 Share Posted June 23, 2009 I'd chamber a bunch of them and look for setback. If they really were jumping from 1100 to 1400+ the recoil and blast would change dramatically, they would be VIOLENT in a G19. Universal will spike dramatically with setback, but 300+ fps should be noted when the shot was fired without the chrono. Link to comment Share on other sites More sharing options...
FLL1911 Posted June 23, 2009 Share Posted June 23, 2009 About a month ago I had similar experience. I was testing some loads with 200gr lead with 4.2 gr of Clays on a 45ACP and I started having disparate reading on my Chrony. Min=396, max=1123 and average 907 fps. I did not have this extreme difference earlier in the morning, and then I noticed that the sun had moved and I did not have the shade from the range roof – the screens were on the sun. On my other gun chrono earlier the 9major readings came right, but later with 9mm factory (WWB) in the same gun I got things like 261, 6000, 7000 and 986 fps – just impossible. Until better explanation, that was a misreading due to the uneven light on top of the reading screens. Link to comment Share on other sites More sharing options...
Chris_Andersen Posted June 26, 2009 Author Share Posted June 26, 2009 Just read a few posts on the forum about chrono lighting. This was at the end of the day with the setting sun behind me. But the guns were back to back, with several different loads, chrono at 8 ft away, punching holes in a 1 inch group in a 10 yard target, so I think they were all going into the same spot in the chrono I don't think anybody makes an IR setup for the Shooting Chrony line unfortunately....haven't checked their website, but I don't recall it as an option. At 8ft I'm wondering if the shorter barrel on the Glock is spitting some unburned powder (shorter barrel) or the concussion of the round going off it tricking the chrono. I'd try moving it back a couple of feet to see what happens. I tend to set my chrono at 12-15ft. R, Was thinking that may be a variable as well. There is no noticable increase in recoil with those wierd readings, so if it isnt light, it has to be the glock spitting powder. Will try it soon and report back. Have had some home projects, and havent been able to play with guns this week. Link to comment Share on other sites More sharing options...
Graham Smith Posted June 26, 2009 Share Posted June 26, 2009 I have had similar problems (altho not that dramatic) with my G19. There seemed to be a couple things going on that contributed to it. First off, the indoor range where I can set up the chrono doesn't give me quite as much distance between my gun and the chrono as I would like. That makes me wonder if it is reacting to some powder spitting. But more important, I'm not allowed to put up a target behind the chrono so that I can be sure I'm consistently shooting down the center of the alley. The only thing I have to go by is a target down at 50'. This makes me wonder if my shots are running too high or low, or too much to one side. FWIW, I don't seem to have quite as much variation with my G35, but I'm using completely different powders for it. Link to comment Share on other sites More sharing options...
Chris_Andersen Posted June 28, 2009 Author Share Posted June 28, 2009 So Bart you were correct. Just got back from the range. Moved the Chrono back to 12 ft...no problems whatsoever. Very consistent numbers in both guns. Thanks! Link to comment Share on other sites More sharing options...
bwit Posted June 28, 2009 Share Posted June 28, 2009 Bart, you da man !!!!! Good call Link to comment Share on other sites More sharing options...
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