praetorian97 Posted May 9, 2014 Share Posted May 9, 2014 Ok so I need some solid advice. I live at 2700 FT Elevation. Travelling to a 500 FT elevation. Weather Temps are irrelevant in the equation because we are very similar. I chronoed today at 929-958-963-931-942-924-943-940-938 I need to be at 918 Min. Should I bump my charge up? I really want to stay where I am at. Link to comment Share on other sites More sharing options...
motosapiens Posted May 9, 2014 Share Posted May 9, 2014 I think you should freak the f*$ out, and stay awake nights, and be nervous, and panic, and have 7 redbulls. Seriously, I think temp is a much bigger issue than altitude, but I could be wrong. Perhaps you need to google 'altitude vs chrono'. I'm good at math and I would be comfortable with those numbers, especially if you got them from more than 1 chrono. I was cutting it close with the load I chrono'd sunday, but it wasn't my match ammo. I'm going to try and get out tomorrow afternoon and check the match ammo on my chrono. It may help the peace of mind for several of us to chrono over multiple devices. I think alford is planning on going out tomorrow too, but I don't know when. I will also be available sunday mid-day. Link to comment Share on other sites More sharing options...
praetorian97 Posted May 9, 2014 Author Share Posted May 9, 2014 If we are going to have similar results I feel warm and fuzzy. I may have to make a road trip there before Area 1 just to chrono haha. Link to comment Share on other sites More sharing options...
motosapiens Posted May 9, 2014 Share Posted May 9, 2014 If worse comes to worst, just shoot alphas. It is much worse for me if I don't make PF in production. I like to see 133-135, but i was hitting 128-130 with my old practice ammo last weekend. I did bump up my match ammo .05 grain or so tho when I loaded it, so hopefully it will show up a little higher. After chamber checking and carefully inspecting the primer seating I would hate to have to load another batch. Link to comment Share on other sites More sharing options...
Hi-Power Jack Posted May 9, 2014 Share Posted May 9, 2014 Just me, I guess, but I'd want to see more than nine shots thru a chrono ... That low reading of 924 is pretty close to 918 ... But, that's just me. Link to comment Share on other sites More sharing options...
motosapiens Posted May 9, 2014 Share Posted May 9, 2014 Just me, I guess, but I'd want to see more than nine shots thru a chrono ... That low reading of 924 is pretty close to 918 ... But, that's just me. I'm good at math, so i'm happy with 5 shots through a chrono for testing. there's nothing wrong with a belt AND suspenders, but even if you have 1 out of every 10 *below* pf, you still have astronomical odds against choosing 4 such rounds at a match. Link to comment Share on other sites More sharing options...
praetorian97 Posted May 9, 2014 Author Share Posted May 9, 2014 I decided to bust out another 500 @5.2. We have the chrono available for courtesy checks before the match so I will run both through and see what will work. Thinking 5.1 will be fine but a crutch is always nice. Link to comment Share on other sites More sharing options...
motosapiens Posted May 9, 2014 Share Posted May 9, 2014 I decided to bust out another 500 @5.2. We have the chrono available for courtesy checks before the match so I will run both through and see what will work. Thinking 5.1 will be fine but a crutch is always nice. That's a good plan. based on my chrono today, I may do a second batch of match ammo and do the same thing. I know I'll shoot them eventually. Link to comment Share on other sites More sharing options...
Parallax3D Posted May 9, 2014 Share Posted May 9, 2014 Ok so I need some solid advice. I live at 2700 FT Elevation. Travelling to a 500 FT elevation. Weather Temps are irrelevant in the equation because we are very similar. I chronoed today at 929-958-963-931-942-924-943-940-938 I need to be at 918 Min. Should I bump my charge up? I really want to stay where I am at. Elevation is irrelevant. Smokeless powders have their own oxidizer built into the formulation. Link to comment Share on other sites More sharing options...
motosapiens Posted May 9, 2014 Share Posted May 9, 2014 Ok so I need some solid advice. I live at 2700 FT Elevation. Travelling to a 500 FT elevation. Weather Temps are irrelevant in the equation because we are very similar. I chronoed today at 929-958-963-931-942-924-943-940-938 I need to be at 918 Min. Should I bump my charge up? I really want to stay where I am at. Elevation is irrelevant. Smokeless powders have their own oxidizer built into the formulation. it can't be totally irrelevant since bullets have friction against air and air is more dense at lower elevations (why speed records are usually set at altitude). But it might not be significant at shorter distances. Probably no change in muzzle velocity. Link to comment Share on other sites More sharing options...
Lifeislarge Posted May 9, 2014 Share Posted May 9, 2014 Ok so I need some solid advice. I live at 2700 FT Elevation. Travelling to a 500 FT elevation. Weather Temps are irrelevant in the equation because we are very similar. I chronoed today at 929-958-963-931-942-924-943-940-938 I need to be at 918 Min. Should I bump my charge up? I really want to stay where I am at.Elevation is irrelevant. Smokeless powders have their own oxidizer built into the formulation. it can't be totally irrelevant since bullets have friction against air and air is more dense at lower elevations (why speed records are usually set at altitude). But it might not be significant at shorter distances. Probably no change in muzzle velocity.Ehem... Had to chime in. Speed records are usually set in Death Valley which sits below sea level. Richer concentration of oxygen allows for more fuel which makes for a bigger bang for the same cylinder displacement. Link to comment Share on other sites More sharing options...
Parallax3D Posted May 12, 2014 Share Posted May 12, 2014 (edited) Ehem... Had to chime in. Speed records are usually set in Death Valley which sits below sea level. Richer concentration of oxygen allows for more fuel which makes for a bigger bang for the same cylinder displacement. Exactly! More oxygen allows for the use of more fuel, and a bigger bang, thus more power. That's why people use things like turbos, superchargers, and nitrous oxide. But as I said, smokeless powder has it's own oxidizer, so the density of the oxygen in the air is irrelevant. You can fire a gun in the vacuum of outer space! Edited May 12, 2014 by Parallax3D Link to comment Share on other sites More sharing options...
Seth Posted May 12, 2014 Share Posted May 12, 2014 I like a 176. It always makes power. Can't tell the difference after the beep anyway. Link to comment Share on other sites More sharing options...
pjb45 Posted May 12, 2014 Share Posted May 12, 2014 I chrono at 5,100 feet and shoot A2 at 2,000 feet and Nationals even lower. My chrono data is almost the exact same as at the matches. I keep my rounds at 167-169 PF and have never be close to not making major. Of course I use VV320 which is amazingly consistent. Link to comment Share on other sites More sharing options...
motosapiens Posted May 12, 2014 Share Posted May 12, 2014 Ok so I need some solid advice. I live at 2700 FT Elevation. Travelling to a 500 FT elevation. Weather Temps are irrelevant in the equation because we are very similar. I chronoed today at 929-958-963-931-942-924-943-940-938 I need to be at 918 Min. Should I bump my charge up? I really want to stay where I am at.Elevation is irrelevant. Smokeless powders have their own oxidizer built into the formulation. it can't be totally irrelevant since bullets have friction against air and air is more dense at lower elevations (why speed records are usually set at altitude). But it might not be significant at shorter distances. Probably no change in muzzle velocity.Ehem... Had to chime in. Speed records are usually set in Death Valley which sits below sea level. Richer concentration of oxygen allows for more fuel which makes for a bigger bang for the same cylinder displacement. ok. that explains bonneville salt flats. lol. Oddly, I see no mention of death valley in the land speed record archives: http://en.wikipedia.org/wiki/Land_speed_record . That probably just means I'm not focusing on the right sort of vehicle. You do make a valid off-topic point however, then in some cases there is more going on than just air resistance. At very high speeds, it *appears* that there is more to gain by reducing air-resistance than by increasing oxygen. Bicycle and speed-skating records tend to be set at altitude. OTOH, off-road motorcycles don't generally go fast enough for it to be an issue, so they run stronger at low altitudes. Link to comment Share on other sites More sharing options...
praetorian97 Posted May 12, 2014 Author Share Posted May 12, 2014 I chrono at 5,100 feet and shoot A2 at 2,000 feet and Nationals even lower. My chrono data is almost the exact same as at the matches. I keep my rounds at 167-169 PF and have never be close to not making major. Of course I use VV320 which is amazingly consistent. If my FPS is the same when I hit the 2000 elevation drop then I will know for sure. Will find out in 4 days and update here. At a 9 shot avg I PF at 168. Sample 4 from that same shot spread Im at 171. I really want to shoot that but I brought a batch of 5.2 just in case. I'm finding with N320 and my gun I get about a 15-20 FPS bump every .1 grain increase. Link to comment Share on other sites More sharing options...
mjohn Posted May 12, 2014 Share Posted May 12, 2014 I chrono at 5,100 feet and shoot A2 at 2,000 feet and Nationals even lower. My chrono data is almost the exact same as at the matches. I keep my rounds at 167-169 PF and have never be close to not making major. Of course I use VV320 which is amazingly consistent. If my FPS is the same when I hit the 2000 elevation drop then I will know for sure. Will find out in 4 days and update here. At a 9 shot avg I PF at 168. Sample 4 from that same shot spread Im at 171. I really want to shoot that but I brought a batch of 5.2 just in case. I'm finding with N320 and my gun I get about a 15-20 FPS bump every .1 grain increase. I find the same bump increase as you with N320. However, with your PF being very close to the minimum, you are assuming that all CED M2 chronos (which is the only chrono that I have seen being used at the matches) are calibrated or report the exact same results each and every time and that each and every batch of ammo that you turn out is exactly the same (the exact same OAL, grains dropped and flair and crimp). Personally, I do not want to take that risk and find a comfort zone when all the sampled rounds meet or exceed the minimum by a PF of 5. Does your backup gun have the same chrono results as your primary gun? Link to comment Share on other sites More sharing options...
praetorian97 Posted May 13, 2014 Author Share Posted May 13, 2014 Backup gun is identical gun. Link to comment Share on other sites More sharing options...
JAFO Posted May 15, 2014 Share Posted May 15, 2014 Hoping I did my math right. Your initial 9-shot average velocity is 940.89. Judging from you saying you have 168PF with that 9-shot average, I'm assuming you are using 180gr bullets. The SD for those 9 shots is 12.85, so the low end of your spread would be 940.89-12.85 = 928.04 fps, which would give you 167.05 PF with 180's. Since PF is supposed to be truncated instead of rounded, a small drop to 927.2 fps would put you at 166 PF. You'd need to drop down to 916.1 fps to be down at 164.9 PF, which would be almost 2x your SD. I don't know that much about powder variations and temperature/altitude, but I would prefer a bit more margin. Like moto, my Production loads are 134-136 PF. Link to comment Share on other sites More sharing options...
praetorian97 Posted May 16, 2014 Author Share Posted May 16, 2014 Boom. Same velocities today through the unofficial chrono check. 20 degree temp increase 2k ft elevation drop. N320 powder. Link to comment Share on other sites More sharing options...
JAFO Posted May 16, 2014 Share Posted May 16, 2014 Nice! Good luck with the match. Link to comment Share on other sites More sharing options...
SilverBolt Posted May 19, 2014 Share Posted May 19, 2014 The Area-1 chono's and scales were very generous. My MG bullets weighed 3 grains heavy and my average chrono was 20fps higher. Link to comment Share on other sites More sharing options...
2MoreChains Posted May 19, 2014 Share Posted May 19, 2014 (edited) Did you keep the bullet they weighed and then weigh it at home on your scale? Just curious why you think their scale was "generous". Mine (185 gr Precision moly) weighed in a 183.5 gr. Edited May 19, 2014 by 2MoreChains Link to comment Share on other sites More sharing options...
motosapiens Posted May 20, 2014 Share Posted May 20, 2014 my bullet weighed 179.9. within the range i expected. I weighed about 15 or so. I also got about the same velocity, maybe a few fps more because of the warmer temps. Link to comment Share on other sites More sharing options...
SilverBolt Posted May 20, 2014 Share Posted May 20, 2014 I was shooting MG 147gr CMJ's. I weighed 50 at home and they ranged 147-147.2. At A-1 they weighed 150.3. Our entire squad weighed in 3gr heavy. Not complaining. lol. Link to comment Share on other sites More sharing options...
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