B_Seehawer Posted June 14, 2011 Share Posted June 14, 2011 What can cause crazy swings in chrono velocities? Link to comment Share on other sites More sharing options...
RangerTrace Posted June 14, 2011 Share Posted June 14, 2011 What can cause crazy swings in chrono velocities? I'm not sure what "crazy" means to you, but I've had some 50-70 FPS variances. However, I just recently purchased a Competition Electronics chronograph and I'm still learning how to use it. I believe my results were caused from varying light conditions and mixed brass. Link to comment Share on other sites More sharing options...
soundwave Posted June 14, 2011 Share Posted June 14, 2011 Shooting too close to it can cause some crazy numbers too. Make sure you are far enough away from it that it is reading the bullet and not the gasses and powder debris . Link to comment Share on other sites More sharing options...
Greg in VA Posted June 14, 2011 Share Posted June 14, 2011 Muzzle blast will cause some strange things to happen...... Greg in Va Link to comment Share on other sites More sharing options...
CocoBolo Posted June 14, 2011 Share Posted June 14, 2011 (edited) I watched two guys crono the other day. Here is what I call crazy. The first guy shoots a couple shots and they are 930 to 960 pfs, then he takes another shot and it is 2350 fps, so he keeps shooting and the numbers jump around like that. The second guy shoots a few shots (10) and they all come out ok. So they turn to me and ask, what is going on. So I said let me check it with my gun I shoot 5 across and they are all within 20 fps of my normal 1350 fps. This was a high dollar crono with the remote and all that. All shot from the same point. So first guy steps up again and the crono goes nuts 935, 3270, 2350, 920 etc. Now that is what I call crazy reading, because if that 9 mm Glock had a 3270fps round in it there would be tupperware spread out all over Texas. My theory is maybe some debris left in the cases when he loaded them, I set a range on fire one time with burning corn media that was left in my reloads. Depending on the powder, crimp, barrel length, tightness of the barrel, primer, consistency of the bullets and loading, powder drops, you can get some big swings, a big swing is more than 60 fps. Between guns with the same load it can be more. Did I say the average crono can vary 4-5%. So now you have a definition of Crazy that is more than 1000 fps variance with the same load, gun, shooter, same temp time of day sun etc. Crazy load was 124gr MTG with TiteGroup. (if I recall it was 4.0gr). Edited June 14, 2011 by CocoBolo Link to comment Share on other sites More sharing options...
gng4life Posted June 14, 2011 Share Posted June 14, 2011 Distance from the chrono screens and the muzzle account for the most problems with checking your rounds. The second is probably lighting. I have a Millenium and a PACT Mark IV so they are very good chrono's. The only time I've seen crazy numbers like that is when it was late in the day near dark (but now I have an infrared kit so no issues now). What Coco said is also another issue but I've never seen that personally. What chrono was it? What time of day? What weather conditions? What load and gun? Link to comment Share on other sites More sharing options...
CocoBolo Posted June 14, 2011 Share Posted June 14, 2011 Distance from the chrono screens and the muzzle account for the most problems with checking your rounds. The second is probably lighting. I have a Millenium and a PACT Mark IV so they are very good chrono's. The only time I've seen crazy numbers like that is when it was late in the day near dark (but now I have an infrared kit so no issues now). What Coco said is also another issue but I've never seen that personally. What chrono was it? What time of day? What weather conditions? What load and gun? It was late in the afternoon, but not sunset good and bright temp about 80 light wind < 5 mph. Distance to crono about 12-15 feet. The Crono was a CED Millennium 2 Chronograph System. The gun was some kind of Glock 9 mm with 124gr MTG with titegroup @4.0gr short of minor. This is the one that drove it crazy. Guy two had a 40 S&W Beretta 92 also shooting MTG 200gr with titegroup but I don't know how much, reading were consistent. I shot my 9 major OpenGun with 124gr MTG with 7.6gr of Silhouette and the readings were fine. The only odd thing I can think of is he was using Wolf Primers. No moving shadows, which was my first thought, not a tree in sight. Link to comment Share on other sites More sharing options...
B_Seehawer Posted June 15, 2011 Author Share Posted June 15, 2011 Well, my issue is that 3 days before area 5, I am loading a different powder (WST)with 180 grain Montana golds (which I have never used), through a gun that is my backup (which has less than 200 rounds) and I am getting 100 fps swings when chronoing. Range is indoors and light is good, shooting 10 feet from the chrono and my powder measure stays within .1 all the time. Link to comment Share on other sites More sharing options...
kalaur Posted June 15, 2011 Share Posted June 15, 2011 You mentioned you are shooting indoors, perhaps the lighting is fluorescent? Fluorescent lighting can mess with some chronos, even if you use the skyscreens and such. What kind of chrono? Link to comment Share on other sites More sharing options...
B_Seehawer Posted June 15, 2011 Author Share Posted June 15, 2011 Flourescents are turned off and using a halogen. Link to comment Share on other sites More sharing options...
Hi-Power Jack Posted June 15, 2011 Share Posted June 15, 2011 I am loading a different powder (WST)with 180 grain Montana golds (which I have never used), through a gun that is my backup and I am getting 100 fps swings when chronoing. Range is indoors and light is good, shooting 10 feet from the chrono and my powder measure stays within .1 all the time. May not be the chrono - could be the reloads. Different types of brass, varying OAL's, etc. More specifics of your reloads / equipment would make it easier to be more specific. Jack Link to comment Share on other sites More sharing options...
gng4life Posted June 15, 2011 Share Posted June 15, 2011 I'm not sure about halogen (should be okay but not sure) but is there any way to run it outside? Or do you have an IR kit? I've never chrono'ed inside but I would not trust anything but natural lighting or the IR kit. Link to comment Share on other sites More sharing options...
gmg Posted June 15, 2011 Share Posted June 15, 2011 shoot it and put it out of it's misery and get a real good one. Seriously i had to put a piece of cardboard with a 2 - 3 inch hole in it and shoot thru the hole and waited until later in the day. Link to comment Share on other sites More sharing options...
gng4life Posted June 15, 2011 Share Posted June 15, 2011 I am loading a different powder (WST)with 180 grain Montana golds (which I have never used), through a gun that is my backup and I am getting 100 fps swings when chronoing. Range is indoors and light is good, shooting 10 feet from the chrono and my powder measure stays within .1 all the time. May not be the chrono - could be the reloads. Different types of brass, varying OAL's, etc. More specifics of your reloads / equipment would make it easier to be more specific. Jack If it's a total of 100 fps between rounds, I've seen that and it was my reloads. The 100 fps swing was as +/- 50 fps. Now, if you are getting +/- 100 swings (in effect, 200 fps differences), then I would not attribute that to reloads unless the powder drop was very inconsistent. Since your drop is good, I would doubt it's that. Can you give us more details about your velocities and strings? Link to comment Share on other sites More sharing options...
CocoBolo Posted June 15, 2011 Share Posted June 15, 2011 Well, my issue is that 3 days before area 5, I am loading a different powder (WST)with 180 grain Montana golds (which I have never used), through a gun that is my backup (which has less than 200 rounds) and I am getting 100 fps swings when chronoing. Range is indoors and light is good, shooting 10 feet from the chrono and my powder measure stays within .1 all the time. Well, in light of your delima I can tell you that with 180gr MTG and WST you need 5.0 to 5.1 gr to hit 170pf in hot weather at an OAL of 1.185. WST ES and SD is not that good but it is what I shoot, when shooting limited except I use Moly bullets with only 4.7gr. Your results may vary, especially at shorter OAL's where the charge needs to be reduced. I'd say look at the crimp first, if you are crimping the bejesus out of the rounds that could be the culprit. A new barrel should be fast and after 1K rounds slow slightly. I just crimp using the thumb test, thumb on one end bench on the other if the bullet moves it needs more crimp. I don't have my book handy but in it I have a measurement but I can't remember it right now for jacketed bullets. Link to comment Share on other sites More sharing options...
JOHNNYGLOCK Posted June 29, 2011 Share Posted June 29, 2011 I have had a M2 for 6 months and I am still trying to learn how to use it. I have found that light conditions play the biggest roll to get good readings. most sunny days I get readings that seam feasible but than I get 1 or 2 E0/E1 out of a 10shot string. At my range I can shoot 180* so i would have to move the chrono in the sun till those E readings would go away. Usually this is with the sun is high in the sky at the 9 o clock. The best outing I have had with it thus fare was with a overcast sky, It worked great all day with SD reading below 10. The only problem I had on that day is when I switched from pistol to rifle (.223) lots of E1 (missed stop sensor) so my first thought was to big of a blast from rifle (this was at 10') so moved back and back and back intill I was like 30 yards away and still getting E1. So I moved back to 10' and made sure the screen was as level as it could be from me and took out a .22lr and walked the bullets down the beams till they started to read normal which was about 3" from the beam. Than it worked great with .223 as close as 6' away as long as I put those small bullets only 3" from the beams. I think a infrared screen will solve most of the problems people have with chronos. Link to comment Share on other sites More sharing options...
truckmsl Posted July 1, 2011 Share Posted July 1, 2011 (edited) Not trying be be contrary, but I have been getting single digit standard deviations with WST powder. Edited July 1, 2011 by truckmsl Link to comment Share on other sites More sharing options...
truckmsl Posted July 1, 2011 Share Posted July 1, 2011 On a more relevent note - I have seen low batteries cause odd behavior in chronographs. Link to comment Share on other sites More sharing options...
SNSCaster2 Posted July 2, 2011 Share Posted July 2, 2011 I always try to shoot through about 6" above the beams for starters... just to be consistent.. Also, WST almost made me go minor on a hot day a few years ago, which is why I don't use it for major matches anymore. Like mentioned above, use like headstamped brass for more consistent results, and make sure your bullets are consistent in weight. Aside from that, lighting will play tricks with chrono's, which is why I always chrono outdoors. Link to comment Share on other sites More sharing options...
FJRider Posted February 5, 2012 Share Posted February 5, 2012 (edited) Although this thread is a bit old, I'd like to share my experiences with my Chronograph and how I fixed them. I too had varying speed measurements of as much as a 1000+fps or more. Chrono used was an Alpha Shooting Chrony but I think these tips are universal for all. My solution was a number of changes that has resulted in no more issues (at least for me.. YMMV!) 1st: I was too close (under 10 feet), solution was to move out; now I use a commonly recommended 15 feet. Being close allowed the blast gases /particles to reach the chrono before the bullet. 2nd: Lighting was also an issue - at low angles of the sun (common in winter or early/late in the day), the sensors were not seeing the bullet's shadow. My solution was to get the accesory LED lights from Shooting Chrony for the chronograph. Note: flourescent lights are a big no-no's for chronos, their oscillations in brightness confuse the sensors; I noticed that any flourescent lights within 50feet of the chrono could affect it. Lastly, after researching a bit on what other used /did, I decided that isolating the unit from the environment would work best for my uses (both outdoors and indoors) and built a chrono box (a quick Google search will show you lots of pictures) to house the chronograph and the LED lights; box has an integral blast shield (essentially a small hole that you shoot thru to diffuse /reduce any blast gas effects) and a disposable /consumable sun shield on the exit side. You could easily build a blast shield to sit in front of any chrono (just use a small hole, say 3-4in diameter, or a slit, say 2in by 4in) out of a variety of materials (cardboard will work since you are just slowing /diffusing gases, just do not let it get moved around). Good tip for the box is to paint the inside a flat -no gloss at all- black. I recently used the new chrono box setup outdoors in the low angle light of winter (sunlight angle had to be 45deg.. object shadows were completely off to one side) to chrono .223 loads with excellent results -- 71 shots were fired across the chrono and all were measured perfectly fine with no abnormal readings. Now I can focus back on getting those those SD/ES down to size! Cheers! Edited February 6, 2012 by FJRider Link to comment Share on other sites More sharing options...
Csiedmond1 Posted February 6, 2012 Share Posted February 6, 2012 Thanks for that awesome info, I'm looking into buying a chrono and needed this info!!! Link to comment Share on other sites More sharing options...
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